Slashdot Mirror

citpyrc writes: TeslaCrypt, the latest-and-greatest ransomware branch off of the CryptoWall family, claims to the unwitting user that his/her documents are encrypted with "a unique public key generated for this computer". This coudn't be farther from truth. In actuality, the developers of this malware appear to have been lazy and implemented encryption using symmetric AES256 with a decryption key generated on the user's machine. If any of your machines are afflicted, Talos has developed a tool that can be used to generate the user's machine's symmetric key and decrypt all of the ransomed files.

Palljon1123 writes "A stack-based buffer overflow in the Snort intrusion detection system could leave government and enterprise installations vulnerable to remote unauthenticated code execution attacks. The flaw, found by researchers at IBM's ISS X-Force, affects the Snort DCE/RPC preprocessor and could be used to execute code with the same privileges (usually root or SYSTEM) as the Snort binary. No user action is required." Sourcefire has an update to fix the vulnerability in versions 2.6.1, 2.6.1.1, and 2.6.1.2; Heise Security spells out the workaround for the 2.7.0 beta version.

bobdehnhardt writes "The Snort-announce list was burning with the news that CheckPoint has signed an agreement to acquire Sourcefire, the commercial arm of the Snort community. As part of the agreement, CheckPoint will "continue to develop and distribute Snort under the GPL, improve and document the program to stay on the cutting edge and expand the snort.org web site." Here is a message from Snort creator Marty Roesch."

c0dyd asks: "Lately, computer attacks have gained much popularity in the news; however, it is not often that we hear of new software, hardware or 'appliances' that combat malicious code attacks and data intrusions. Obviously, the need is present. I've searched thoroughly for network intrusion detection and prevention systems, but the choices and technologies seem somewhat limited or proprietary-- Snort appears an obvious open source solution for intrusion detection but many users many find it lacking in intrusion prevention capabilities. What do you, the experienced network admin, use for detecting intrusions on the network and how does your network react to those intrusions?"

An anonymous reader writes "Prelude IDS Framework: "Open Source Security's Best Kept Secret" is an overview of the Prelude Project. The article touches upon the long list of devices and log types Prelude understands. As well as Prelude's ability to utilize patched versions of software like Snort, Nagios, Nessus, SamHain, etc. to all report to Prelude. There are also screen shots of two new front ends for Prelude (pylude and prewikka)."

Alascom writes "The Open Source Vulnerability Database project has finally gone live. The project aims to provide comprehensive, free and unbiased (no vendor spin) vulnerability information. The database is being incorporated into such fine open source utilities as SNORT and NESSUS."

j0hnyb1423 writes "Have you ever wanted to be able to connect to that stackless Snort or Hogwash box without walking over to it and plugging in a monitor and keyboard? Well, at last here's your answer - noiptun. Yes, it requires an IP stack to be compiled into the kernel but no IP addresses necessary on the real interface(s). And if stealth IDS setups aren't your bag, then you can at least use it to browse /. without having an IP bound to your linux workstation."

RanmaPlex asks: "I've been asked by a university professor to design a network security lab for use by about 15 students. Designing a course was asked earlier, but little info was discussed on equipment. It needs to be vendor independent if possible. I've got ideas on using virtual machines, patches, IDS, firewalls/vpn and sniffers but would like to know what the Slashdot community can come up with."

Mark Tobenkin writes "Are corporations exploiting the Open Source community? The Linux Public Broadcasting Network has video interviews with Ian Murdock (of Progeny and Debian fame), Martin Roesch (author of Snort), Jeremey White (CEO of CodeWeavers), Bradley Kuhn (FSF), Mike Balma (Linux Business Strategist for HP) and others on the evolving OSS business models. The interviews center around whether integration with proprietary products endangers the Open Source effort or increases consumers' freedom to choose."

Eric Stats writes "Working as a Network Engineer for web-hosting company that prides itself on uptime and network availability, and moonlighting as a part-time Linux administrator, my managers and clients are starting to expect a level of information security knowledge from me. I decided that if I wanted to take my career to the next level, I needed to develop some security-specific skills. I heard a lot about the open source Intrusion Detection System (IDS), Snort from friends and co-workers (mostly that it was a pain to get running, and an even bigger pain to understand what it was doing)." To get past those frustrations, Eric looked at two more books on Snort (and compares them to the already-reviewed Intrusion Detection with Snort ); read on below for his take on what each offers. Intrusion Detection with SNORT: Advanced IDS Techniques Using SNORT, Apache, MySQL, PHP, and ACID; Intrusion Detection with Snort; Snort 2.0 Intrusion Detection author (See each) pages (See each) publisher (See each) rating (See each) reviewer Eric Stats ISBN (See each) summary (See each)

I ran Snort at home for a while, using the online docs, but I could never get a handle on which output plugin to use (When to log? When to alert?), how to email alerts to myself (I later found out Snort doesn't natively do this), and how to create signatures from packet captures (no online docs at all for this). When I did get The Pig running, it filled up my log directory with thousands of small alert files, which ended up being in tcpdump format. This frustrated the hell out of me, so I decided I needed to find a good book on Snort, as the online docs simply did not describe how to use Snort from start to finish.

In the past few months, an assortment of books have come out on Snort. Because it has begun to eclipse closed-source, multimillion dollar IDSes in terms of raw performance and features, much attention is currently focused on Snort. Naturally, when an open source project achieves this level of notoriety, publishers, venture capitalists, and corporations want to get in on the game. The flood of Snort books is a testament to this, but it doesn't mean they were all created equally. This book review covers the three books on Snort currently available (we will see another two Snort books later this winter). It covers what is good about them, what is bad, and who the target audience is for each. If you are looking to learn intrusion detection the open source way, or simply do not have a million-dollar IT security budget, these books are a good starting point.

Each of these three books serves a different purpose and consequently is appropriate for a different reader. In summary, Rafeeq Rehman's Intrusion Detection with Snort: Advanced IDS Techniques Using SNORT, Apache, MySQL, PHP, and ACID presents a concise, quick-start guidebook to getting Snort up and running fast. He doesn't delve into the details of Snort, and this book makes a perfect choice for a reader who wants to get The Pig up and running quickly and move on to something else.

The whole gaggle of authors that put together Snort 2.0 Intrusion Detection created a much-needed user manual for Snort. This book makes for good desktop reference, but assumes you understand the core concepts of intrusion detection, or have significant field experience with Snort. It is also somewhat convoluted to read; I suppose it's inevitable when you have 12 authors working on a single book, it is going to come out somewhat disjointed and jumbled. If I hadn't read the other two books first, I doubt I would have been able to piece together what this book is talking about in places. (Such as referring to Barnyard logs in one chapter and "unified binary format" in another; how is the reader going to know they are the same?)

Lastly, Jack Koziol's Intrusion Detection with Snort is a guidebook for using Snort in the real world, either on small networks or in large corporate settings. Like any security tool, Snort is only as effective as its operator. Snort can do an enormous number of things, but if you don't understand the "how and why" you aren't going to be able to apply your knowledge in unexpected, different, or new situations. Koziol's book bridges the gap and teaches you the nitty-gritty Snort details not found in online docs, as well as how to apply your newfound IDS knowledge in practice. This book does lack in terms of screenshots and diagrams, which can be frustrating at points. Instead of a paragraph of text, a simple diagram would have sufficed.

Intrusion Detection with SNORT: Advanced IDS Techniques Using SNORT, Apache, MySQL, PHP, and ACID author Rafeeq Rehman pages 288 publisher Prentice Hall rating 7/10 ISBN 0131407333

I first picked up Rehman's Intrusion Detection with Snort: Advanced IDS Techniques Using SNORT, Apache, MySQL, PHP, and ACID. Rehman's book is also a member of the Bruce Perens Open Source Series. All of the books in his series are published under the OPL. Overall, Rehman's book served as a good intro to Snort. I followed the examples, used some of the custom startup and log-rotation scripts, and got Snort working for the first time. I also learned of ACID, which is a PHP-based GUI for Snort, put out by Carnegie Mellon's CERT/CC. It makes managing alerts from Snort much less time-intensive. It was an exciting experience, but the book left me in the dark on a number of concepts that I knew I needed to learn. I still didn't understand what I was getting out of Snort; I had so many alerts I couldn't "tune out the noise." I didn't know when to use log or alert plugins, so I just turned on both for safety's sake. I also found that Snort was dropping packets (meaning it wasn't able to keep up with the traffic load going to my webservers hosted at home), but didn't find any way to fix this problem. This setup was fine for experimenting at home, but I didn't feel I would be able to use Snort in a mission-critical corporate setting yet.

Intrusion Detection with Snort author Jack Koziol pages 400 publisher SAMS Publishing rating 9/10 ISBN 157870281X

I thumbed through Jack Koziol's Intrusion Detection with Snort at the bookstore, and it seemed to have some more detailed descriptions of using Snort. It also had a lot of the planning, deployment, and maintenance activities you never think of until you are faced with one at 2 a.m. (such as how to upgrade Snort in an organized manner after a vicious integer overflow exploit is released for a core Snort component). It is also the most popular Snort book, so I figured I would buy it. When I took it home, I learned where to place Snort on a network, and what advantages and disadvantages there are to different IDS sensor placement strategies, something I had never considered.

Koziol's book also had the technical detail I was in desperate need of. I learned how to use Barnyard to spool alerts, which keeps Snort from dropping packets. I got to write my own attack signatures from scratch by using Ethereal packet captures in an controlled lab environment. I created a targeted ruleset; it enables specific attack signatures based on what I actually have running on my network, simply using nmap and some complicated perl scripts. The targeted ruleset went a long way to reducing false alerts, and is now a selling product from the Snort commercial vendor, Sourcefire. I finally got email alerts working using syslog-ng with Snort. The book ends with some more advanced content, namely using Snort as an Intrusion Prevention device. You can setup Snort to block packets that match a signature, using Inline Snort, or you can have Snort reconfigure routers and firewalls to block offending IP addresses, using SnortSam. I've experimented with Inline Snort as part of a honeypot, but, as the author points out, this is not yet production-safe, as it can easily be used by attackers to disrupt network availability.

Snort 2.0 Intrusion Detection authors Jay Beale, Anne Carasik, Aidan Carty, Scott Dentler, Adam M. Doxtater, Wally Eaton, Jeremy Faircloth, James C. Foster, Vitaly Osipov, Jeffrey Posluns, Ryan Russell, Brian Caswell pages 485 publisher Syngress rating 4/10 ISBN 1931836744

The final Snort book in this review is Snort 2.0 Intrusion Detection. This book has a lot of the screenshots and figures that the Koziol and Rehman books leaves out. It also contains a lot of useful diagrams, about one for every other page, and a CD-ROM with all of the Snort source and a pdf version of the book. This book, and the Koziol book, cover Snort version 2.0, which isn't all that much different from version 1.9 covered in the Rehman book. Still, it is nice to have the most up-to-date documentation, but it doesn't make the Rehman book any less effective. This book has the most reference material in it, over 500 pages' worth, and it has very organized user manual-like descriptions of important Snort components (preprocessors, output plugins, and rules). Keep in mind that this book was created more as a user manual rather than an implementer's guide. You aren't going to see planning, deployment, and maintenance activities as well as technical deployment examples, as in the Koziol book. And, you aren't going to find a concise quick-start guide such as the Rehman book.

In summary, you aren't going to find anything in this book that isn't in the other two. What you will find is lengthy descriptions, and a lot more screenshots. As stated before, Snort 2.0 Intrusion Detection was written by 12 different people (one of them a Sourcefire employee and Snort.org website maintainer, Brian Caswell). This is obviously done by the publisher to get the book out as fast as possible, which is important for technology book publishers as books are outdated quickly, but has the end result of a disjointed book that contradicts itself in many areas. An example: one author stresses how deadly important it is for us to only use the latest Snort version, while another tells us to use the CDROM that comes with the book, which contains an outdated version of Snort.

You can clearly tell a different authors worked on different chapters, as the style and format change frequently. You can also tell that the authors didn't talk to each other much, as you will find one author referring to something in one chapter (unified binary format) that he expected to have been explained in a previous chapter. In print, the concept was not explained until later, which can be really frustrating if you are not a Snort pro. Additionally, there are enough grammatical errors in the book to be distracting, and, much like a vendor-provided user manual, the chapters don't logically flow from one to the next. If you do purchase this book, this slashdotter would recommend it as a supplement to either the Rehman or Koziol book.

You can purchase Intrusion Detection with SNORT: Advanced IDS Techniques Using SNORT, Apache, MySQL, PHP, and ACID , Intrusion Detection with Snort , and Snort 2.0 Intrusion Detection from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.

Eric Stats writes "Working as a Network Engineer for web-hosting company that prides itself on uptime and network availability, and moonlighting as a part-time Linux administrator, my managers and clients are starting to expect a level of information security knowledge from me. I decided that if I wanted to take my career to the next level, I needed to develop some security-specific skills. I heard a lot about the open source Intrusion Detection System (IDS), Snort from friends and co-workers (mostly that it was a pain to get running, and an even bigger pain to understand what it was doing)." To get past those frustrations, Eric looked at two more books on Snort (and compares them to the already-reviewed Intrusion Detection with Snort ); read on below for his take on what each offers. Intrusion Detection with SNORT: Advanced IDS Techniques Using SNORT, Apache, MySQL, PHP, and ACID; Intrusion Detection with Snort; Snort 2.0 Intrusion Detection author (See each) pages (See each) publisher (See each) rating (See each) reviewer Eric Stats ISBN (See each) summary (See each)

I ran Snort at home for a while, using the online docs, but I could never get a handle on which output plugin to use (When to log? When to alert?), how to email alerts to myself (I later found out Snort doesn't natively do this), and how to create signatures from packet captures (no online docs at all for this). When I did get The Pig running, it filled up my log directory with thousands of small alert files, which ended up being in tcpdump format. This frustrated the hell out of me, so I decided I needed to find a good book on Snort, as the online docs simply did not describe how to use Snort from start to finish.

In the past few months, an assortment of books have come out on Snort. Because it has begun to eclipse closed-source, multimillion dollar IDSes in terms of raw performance and features, much attention is currently focused on Snort. Naturally, when an open source project achieves this level of notoriety, publishers, venture capitalists, and corporations want to get in on the game. The flood of Snort books is a testament to this, but it doesn't mean they were all created equally. This book review covers the three books on Snort currently available (we will see another two Snort books later this winter). It covers what is good about them, what is bad, and who the target audience is for each. If you are looking to learn intrusion detection the open source way, or simply do not have a million-dollar IT security budget, these books are a good starting point.

Each of these three books serves a different purpose and consequently is appropriate for a different reader. In summary, Rafeeq Rehman's Intrusion Detection with Snort: Advanced IDS Techniques Using SNORT, Apache, MySQL, PHP, and ACID presents a concise, quick-start guidebook to getting Snort up and running fast. He doesn't delve into the details of Snort, and this book makes a perfect choice for a reader who wants to get The Pig up and running quickly and move on to something else.

The whole gaggle of authors that put together Snort 2.0 Intrusion Detection created a much-needed user manual for Snort. This book makes for good desktop reference, but assumes you understand the core concepts of intrusion detection, or have significant field experience with Snort. It is also somewhat convoluted to read; I suppose it's inevitable when you have 12 authors working on a single book, it is going to come out somewhat disjointed and jumbled. If I hadn't read the other two books first, I doubt I would have been able to piece together what this book is talking about in places. (Such as referring to Barnyard logs in one chapter and "unified binary format" in another; how is the reader going to know they are the same?)

Lastly, Jack Koziol's Intrusion Detection with Snort is a guidebook for using Snort in the real world, either on small networks or in large corporate settings. Like any security tool, Snort is only as effective as its operator. Snort can do an enormous number of things, but if you don't understand the "how and why" you aren't going to be able to apply your knowledge in unexpected, different, or new situations. Koziol's book bridges the gap and teaches you the nitty-gritty Snort details not found in online docs, as well as how to apply your newfound IDS knowledge in practice. This book does lack in terms of screenshots and diagrams, which can be frustrating at points. Instead of a paragraph of text, a simple diagram would have sufficed.

Intrusion Detection with SNORT: Advanced IDS Techniques Using SNORT, Apache, MySQL, PHP, and ACID author Rafeeq Rehman pages 288 publisher Prentice Hall rating 7/10 ISBN 0131407333

I first picked up Rehman's Intrusion Detection with Snort: Advanced IDS Techniques Using SNORT, Apache, MySQL, PHP, and ACID. Rehman's book is also a member of the Bruce Perens Open Source Series. All of the books in his series are published under the OPL. Overall, Rehman's book served as a good intro to Snort. I followed the examples, used some of the custom startup and log-rotation scripts, and got Snort working for the first time. I also learned of ACID, which is a PHP-based GUI for Snort, put out by Carnegie Mellon's CERT/CC. It makes managing alerts from Snort much less time-intensive. It was an exciting experience, but the book left me in the dark on a number of concepts that I knew I needed to learn. I still didn't understand what I was getting out of Snort; I had so many alerts I couldn't "tune out the noise." I didn't know when to use log or alert plugins, so I just turned on both for safety's sake. I also found that Snort was dropping packets (meaning it wasn't able to keep up with the traffic load going to my webservers hosted at home), but didn't find any way to fix this problem. This setup was fine for experimenting at home, but I didn't feel I would be able to use Snort in a mission-critical corporate setting yet.

Intrusion Detection with Snort author Jack Koziol pages 400 publisher SAMS Publishing rating 9/10 ISBN 157870281X

I thumbed through Jack Koziol's Intrusion Detection with Snort at the bookstore, and it seemed to have some more detailed descriptions of using Snort. It also had a lot of the planning, deployment, and maintenance activities you never think of until you are faced with one at 2 a.m. (such as how to upgrade Snort in an organized manner after a vicious integer overflow exploit is released for a core Snort component). It is also the most popular Snort book, so I figured I would buy it. When I took it home, I learned where to place Snort on a network, and what advantages and disadvantages there are to different IDS sensor placement strategies, something I had never considered.

Koziol's book also had the technical detail I was in desperate need of. I learned how to use Barnyard to spool alerts, which keeps Snort from dropping packets. I got to write my own attack signatures from scratch by using Ethereal packet captures in an controlled lab environment. I created a targeted ruleset; it enables specific attack signatures based on what I actually have running on my network, simply using nmap and some complicated perl scripts. The targeted ruleset went a long way to reducing false alerts, and is now a selling product from the Snort commercial vendor, Sourcefire. I finally got email alerts working using syslog-ng with Snort. The book ends with some more advanced content, namely using Snort as an Intrusion Prevention device. You can setup Snort to block packets that match a signature, using Inline Snort, or you can have Snort reconfigure routers and firewalls to block offending IP addresses, using SnortSam. I've experimented with Inline Snort as part of a honeypot, but, as the author points out, this is not yet production-safe, as it can easily be used by attackers to disrupt network availability.

Snort 2.0 Intrusion Detection authors Jay Beale, Anne Carasik, Aidan Carty, Scott Dentler, Adam M. Doxtater, Wally Eaton, Jeremy Faircloth, James C. Foster, Vitaly Osipov, Jeffrey Posluns, Ryan Russell, Brian Caswell pages 485 publisher Syngress rating 4/10 ISBN 1931836744

The final Snort book in this review is Snort 2.0 Intrusion Detection. This book has a lot of the screenshots and figures that the Koziol and Rehman books leaves out. It also contains a lot of useful diagrams, about one for every other page, and a CD-ROM with all of the Snort source and a pdf version of the book. This book, and the Koziol book, cover Snort version 2.0, which isn't all that much different from version 1.9 covered in the Rehman book. Still, it is nice to have the most up-to-date documentation, but it doesn't make the Rehman book any less effective. This book has the most reference material in it, over 500 pages' worth, and it has very organized user manual-like descriptions of important Snort components (preprocessors, output plugins, and rules). Keep in mind that this book was created more as a user manual rather than an implementer's guide. You aren't going to see planning, deployment, and maintenance activities as well as technical deployment examples, as in the Koziol book. And, you aren't going to find a concise quick-start guide such as the Rehman book.

In summary, you aren't going to find anything in this book that isn't in the other two. What you will find is lengthy descriptions, and a lot more screenshots. As stated before, Snort 2.0 Intrusion Detection was written by 12 different people (one of them a Sourcefire employee and Snort.org website maintainer, Brian Caswell). This is obviously done by the publisher to get the book out as fast as possible, which is important for technology book publishers as books are outdated quickly, but has the end result of a disjointed book that contradicts itself in many areas. An example: one author stresses how deadly important it is for us to only use the latest Snort version, while another tells us to use the CDROM that comes with the book, which contains an outdated version of Snort.

You can clearly tell a different authors worked on different chapters, as the style and format change frequently. You can also tell that the authors didn't talk to each other much, as you will find one author referring to something in one chapter (unified binary format) that he expected to have been explained in a previous chapter. In print, the concept was not explained until later, which can be really frustrating if you are not a Snort pro. Additionally, there are enough grammatical errors in the book to be distracting, and, much like a vendor-provided user manual, the chapters don't logically flow from one to the next. If you do purchase this book, this slashdotter would recommend it as a supplement to either the Rehman or Koziol book.

You can purchase Intrusion Detection with SNORT: Advanced IDS Techniques Using SNORT, Apache, MySQL, PHP, and ACID , Intrusion Detection with Snort , and Snort 2.0 Intrusion Detection from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.

You asked nmap creator Fyodor many excellent questions, and his answers (below) are just as excellent. You'll want to set aside significant time to read and digest this interview, because Fyodor didn't just toss off a few words, but put some real time and energy into his answers.

1) Interesting stories involving nmap?
by Neologic

Nmap has obviously become a huge success in the *nix world. I would wager that practically all sysadmins and security folk use nmap. With this sort of use by such creative and lazy people, there must have been some interesting stories involving nmap, perhaps unusual uses of it, or funny anecdotes. Are there any you would like to share?

Fyodor

The coolest use ever was undoubtedly when Trinity used it to try and save the human race :). But the use I find most gratifying are the Chinese students and residents who have written me about how they use Nmap to locate open proxies. These proxies allow for surfing the uncensored Internet, including the news, educational, pornographic, religious, open source software, government, political, search engine, and human rights sites that are blocked by the Great Firewall of China.

Many of the best features in Nmap came from the user community in ideas if not implementation. For example, the protocol scan (-sO) determines what IP protocols (TCP, UDP, GRE, etc.) a host is listening for. I had not thought of this, but the idea and patch came out of the blue one day in an email from Gerhard Rieger. On another day, a guy named Saurik sent a patch called Nmap+V that allows Nmap to do basic service/version fingerprinting against open ports. It has attracted a cult following, and I plan to add similar functionality to Nmap this year. The initial Windows port by eEye arrived similarly. Despite all these great suggestions, certain other user-contributed ideas are not on the agenda.

Then there are a small handful of users who detect problems nobody else would ever notice, like 4 byte/host memory leaks. They send me error messages with notes saying the bug happens "about once per 700,000 IPs". I have no idea what these guys are up to, but some have been sending me this kind of mail for years. They can't be spammers, as they are intelligent and also use more sophisticated scan techniques than you would need to just find SMTP servers.

2) Recent increases in anal-retentiveness...?
by Zeriel

There's been a marked increase in system administrators thinking that anything even remotely resembling a network scan is eeeeevil (case in point, last year I almost got kicked out of college for scanning port 80 on my dorm subnet looking for interesting websites to read)...

What do you think can be done to make scanning IP addresses/ports have less of a negative stigma? This is in the same sort of category as legit vs. illegit uses of anything else (P2P, whatever)--what's the rationale for punishing something that could maybe lead to criminal activity, and how can we make network scanning tools have practical uses again?

Fyodor

That is an excellent question, and one that concerns me as well. But first, I think your final statement is too extreme. I would guess 90% of network scanning is non-controversial. You will rarely be badgered for scanning your own machine or the networks you administer. The controversy comes when scanning other networks. There are a lot of (good and bad) reasons for doing this sort of network exploration. Perhaps you are scanning the other systems in your {dorm, department, cable LAN, conference LAN} to look for publicly shared files (FTP, SMB, WWW, etc.). Or perhaps your just trying to find the IP of a certain printer. Maybe you scanned your favorite web site to see if they are offering any other services, or because you are curious what OS they run. Perhaps you are just trying to test connectivity, or maybe you wanted to do a quick security sanity-check before handing off your credit card details to that ecommerce company. You might be conducting Internet research, or be bored on a rainy afternoon. Or are you conducting reconnaissance in preparation for a breakin attempt?

The remote administrators rarely know your true intentions, and do sometimes get suspicious. The best approach is to get permission first. I've seen a few people with non-administrative roles land in hot water after deciding to "prove" network insecurity by launching an intrusive scan of the entire company or campus. Admins tend to be more cooperative when asked in advance than when woken up at 3AM by an IDS alarm claiming they are under massive attack.

You compared Nmap to P2P tools in having a "negative stigma". In both cases, one effective way to fight the stigma is to limit your own use to "legitimate" purposes. Use BitTorrent to download RedHat ISOs, but not Matrix Reloaded. Use Nmap to secure and monitor your computers, but not to attack other networks. And if you decide to attack other networks anyway, please be courteous and set the evil bit.

Now I'll admit that I don't always obtain explicit permission before scanning other networks. I don't believe (but IANAL) that a simple port/OS scan of a remote system is or should be illegal. Any machine connected to the Internet will be scanned so often that most admins ignore such "white noise" anyhow. But scan other networks often enough, and someone will eventually complain. So my advice would be:

1. Don't do anything controversial from your work or school connections. Even though your intentions may be good, you have too much to lose if someone in power (boss, dean) decides you are a malicious cracker. Do you really want to explain your actions to someone who may not even understand the terms "port scanner" or "packet"? Spend $10 bucks a month for a dialup or shell account. You didn't really violate this rule, as scanning your dorm subnet for just port 80 should not even be remotely controversial!
2. Target your scan as tightly as possible. If you are only looking for web servers, specify -p80 rather than scanning all 65,535 TCP ports on each machine. If you are only trying to find available hosts, do an Nmap ping scan. Don't scan a /16 when a /24 will suffice. The random scan mode now takes an argument specifying the number of hosts, rather than running forever. So consider -iR 1000 rather than -iR 10000 if the former is sufficient. Use the default timing (or even "-T Polite") rather than "-T Insane".
3. Nmap offers many options for stealthy scans, including source-IP spoofing, decoy scanning, and the more recent Idle Scan technique. But remember there is always a trade-off. You will be harder to detect if you launch scans from an open WAP far from your house, with 17 decoys, while doing followup probes through a chain of 9 open proxies. But if anyone (such as Tsutomu Shimomura) does track you down, they will be mighty suspicious of your intentions.

I occasionally consider adding some sort of "notification packet" prior to a scan that would give hosts the chance to respond and opt-out. This would be like the /robots.txt directives currently used to control polite Web robots. Perhaps the format could even include a text string that IDS systems could log, like: nmap -sS -p- -O -m "Direct questions about this scan to ops at x3512" 192.168.0.0/16 nmap -sS -p- -O -m "mY n4m3 iZ Zer0 |<00L and I'll 0wn j0o%#@" targetcompany.com/24 Of course Nmap would have an option to omit the notification or to send it and ignore any negative responses. Some scanners, such as ISS Internet Scanner already send out NetBIOS popup messages to scanned hosts by default, and other scanners use syslog. I won't be adding any features like this to Nmap unless I see substantial demand and the obvious issues are worked out.

3) OS fingerprinting
by neoThoth

What are the latest advances in fingerprinting networked devices that seem most promising to you? I have started reading papers on HTTP fingerprinting and such and wonder how these will figure into the NMAP architecture. What are the most elusive OS's that aren't on the NMAP OS fingerprint database?

Fyodor

There are a number of OS detection techniques I hope to add this year. One is to guess (or calculate) the initial TTL of response packets, since this varies by OS. Some operating systems also "reflect" your own chosen TTL under various circumstances. Then there are some newer TCP options, such as selective ack that I might test for. Explicit Congestion Notification (RFC 2481/3168) also shows promise. I'll probably add all of these at once later this year, after discussions with the Nmap-dev list. If you wish to participate, you can join that list by sending a blank email to nmap-dev-subscribe@insecure.org. There is also a low volume, moderated list for announcements about Nmap, Insecure.org, and related projects. You can join the 15,000 current members by mailing nmap-hackers-subscribe@insecure.org [archives].

While adding new fingerprinting techniques is fun and exciting, improving the signature database often ads more value. The DB now contains more than 850 signatures, from the Acorn RISC OS and Aironet wireless LAN bridge to the ZoomAir wireless gateway and Zyxel Prestige routers. We're talking gaming consoles, phones, PBX systems, PDAs, webcams, networked power switches, you name it! New fingerprints are submitted daily.

Application level fingerprinting (including HTTP) is coming. I usually regret stating dates, but I hope to develop this functionality within the next 3 months.

4) Stepping into a network security career
by Anonymous Coward

I'll be graduating this month with a shiny new BS in Computer Science. I've done plenty of Unix sysadmin work throughout college and even deployed some high-interaction honeynets. I'm very interested in network security and systems programming. Do you have any advice for people in my situation who want to head into a career in network security?

Fyodor

Congratulations on your graduation! Unfortunately (for newcomers), the security field is one that often expects substantial experience and references. This is partly because these jobs require extraordinary trust, and also because of an aversion to mistakes. Everyone makes mistakes, but they can be extraordinarily costly in security and neophytes tend to make more of them. But don't lose hope! Talented security minds are still in very high demand, just be aware that you will have to work even harder to prove yourself.

Here are my suggestions for anyone starting out in network security, whether for fun or profit:

Step 1: Learn everything you can

1. You may wish to start with reading a general overview of security, such as Practical Unix and Internet Security 3rd Edition.
2. Reading alone won't teach you much. Hands-on experience is critical, so I would set up at least a basic test network. At the very minimum you should have a Unix box or two and a Windows machine (because these are very common in the real world). You can use very cheap machines, or even emulate a large network with virtualization software such as VMWare.
3. Next you should learn more about how attacks are performed. Take a look at the excellent and free Open Source Security Testing Methodology Manual (OSSTMM). This document aims to provide a comprehensive framework for security testing. But it mostly lists tasks to perform, without specifying how to do so. You will gain a lot from this manual if you research the tasks you don't know how to complete, and if you actually try performing the tasks on your test network. If this manual is too curt or hard to follow, you could try a more verbose book on vulnerability assessment, such as Hacking Exposed 4th Edition.
4. Now that you understand many of the general security ideas, it is time to get current. This is one area that has actually become easier in the last decade. The thinking used to be that vulnerability information should only be distributed to well-known and trusted administrators and security researchers through private digests such as Zardoz. This was a disaster for many reasons, and the full disclosure movement was born. In the last couple of years things have started to shift toward more limited ("responsible") disclosure and there is also a disturbing pay-money-for-early-disclosure trend. But information is still much more available than it used to be. Most of the news is carried on mailing lists, and I archive the ones I consider the best at Lists.Insecure.Org. You must subscribe to Bugtraq, and I would also highly recommend pen-test, vuln-dev, and security-basics. Read at least the last 6-12 months of archives. Choose other lists that correspond to your interests. SecurityFocus also offers a security-jobs list which is an excellent resource for finding jobs or just understanding what employers desire.

   There are two major reasons for reading Bugtraq. One is that you must react quickly to new vulnerabilities by patching your servers, notifying your clients, etc. You can get this by simply scanning the subject lines or advisory summaries for bugs that directly apply to you. But then you will miss out on another crucial purpose of Bugtraq. Actually understanding a vulnerability helps you defend against it, exploit it, and identify/prevent similar bugs in the future. When you are lucky, the advisory itself will provide full details on the bug. Check out this excellent recent advisory by Core Security Technologies. Note how they describe exactly how the Snort TCP Stream Reassembly vulnerability works in detail and even include a proof-of-concept demonstration. Unfortunately, not all advisories are so forthcoming. For bugs in Open Source software, you can understand the problem by reading the diff. The next step is to actually write and test an exploit. I would recommend writing at least one for each general class of bug (buffer overflow, format string, SQL injection, etc.) or whenever a bug is particularly interesting.

   Be sure to read the latest issues of Phrack and the research papers posted to the mailing lists. Send your comments and questions to the authors and you may start interesting discussions. Read well-regarded books on the security topics that interest you most.

   I can't emphasize enough that you should intersperse hands-on work with all of this reading. Install unpatched RedHat 8 (or whatever) and run Nmap and Nessus against it. Then compromise it remotely, maybe via the latest Samba hole. Start out with a prewritten exploit from Bugtraq, which isn't quite as easy as it sounds. You may have to modify the 'sploit to compile, brute force the proper offset, etc. Then break in again using a different technique, and your own exploit. Install Ethereal and/or tcpdump and ensure you understand the traffic on your network during both your exploitation and normal network activity. Install Snort on an Internet-facing machine and watch the attacks and probes you'll experience. Wander around your neighborhood with Kismet, Netstumbler, or Wellenreiter on your Laptop or PDA to look for open WAPs. Install DSniff and execute an active MITM attack on an SSH or SSL connection between two of your computers. Take a look at my Top 75 Tools List and ensure you understand what each does and when it would be useful. Try out as many as you can.

5. Take a vacation, or at least a weekend camping! You deserve it! The steps above would probably take at least 3-12 months full-time, depending on your motivation level and the depth and breadth of your research.

Step 2: Now apply your newfound knowledge

Now you have learned enough to be dangerous. At this point, you would have little trouble obtaining most certifications, after studying the specifics of each topic. If your main goal is to find a job quickly, perhaps adding these extra feathers to your cap might be worthwhile. But I think your best bet is to prove your knowledge by joining and contributing to the security community. While this does indeed help others, it isn't an entirely selfless act. It improves your skills, leads to important contacts, and demonstrates your knowledge and ability in a constructive way. The latter is important if securing a career is one of your goals. These steps should also be fun! If not, perhaps you should keep looking at other fields. Here are some ideas:

Start participating with insightful comment and answers on the mailing lists. This is very easy and serves as a great learning experience, way to meet people, and garners some name recognition. If a security manager with a stack of 60 resumes recognizes your name, that is a huge win!

When a new worm or a big new vulnerability comes out, everyone wants to know the details. If you stay up all night disassembling the worm/patch and write the first comprehensive analysis, many folks will find that valuable. And you will learn a lot. Let your first priority be quality - if someone beats you to it, just compare your results with theirs to see if you (or they) missed (or misinterpreted) anything. You can also post your own exploits, although that is more of a political hot potato.

Attending security conferences is a great way to learn, party with fellow hackers, and network (in every sense of the word). Much better is to speak at these conferences. This field changes rapidly so there are always new topics and technologies to discuss. You don't have to be a well-known expert with a long history - just learn your topic well and put in the effort for a quality presentation. You could present at Defcon, at one of the more commercial events, or at a smaller regional con like ToorCon, CodeCon, Hivercon, etc. Among other advantages (often free admission/travel/hotel), this is a great way to meet people with similar interests. I spoke at the latest CanSecWest and have submitted a proposal for the next Defcon.

Now that you've seen and understand a wide variety of software vulnerabilities from your Bugtraq research, start finding your own. You can start by downloading any PHP app from Sourceforge. Most of those are hopelessly vulnerable to Cross-Site-Scripting, SQL injection, and/or remote code execution by "remote include" directives. Many (if not most) Windows shareware daemons are also vulnerable to simple buffer overflows and format-string bugs. Notify the authors and then write an advisory. After a few of these "easy targets", try breaking some more widely deployed programs.

Write a security tool! I could list some suggestions, but by this point you will have many of your own ideas as to what is needed. Scratch an itch.

I hope this helps. If you want more suggestions, Ask Slashdot. From that story, I found this post particularly insightful, especially the emphasis on "people skills". I don't claim to have any, but understand the value :).

5) Have you ever been tempted to use your gifts...
by Tim_F

...in a negative manner?

Have you ever hacked into someone else's computer? Have you ever considered it? What would cause you to think of doing this? Would your tools (nmap, etc.) be enough to allow you to do this?

And if you haven't, why is that the case?

Fyodor

I never do script-kiddie style "hack any random vulnerable box on the Internet" cracking. But sometimes I will launch targeted attacks at specific companies. I'll usually start with just a web browser and various search engines to learn everything I can about my target. I need to understand what the company does, who it partners with, and whether it has any corporate siblings, subsidiaries, or parents. Beyond that, posts by individual employees can be a gold mine. Besides providing names and titles for social engineering and brute force password attacks, the IPs in the mail/news routing headers can be very valuable. One of the reasons I run my own mailing list archive is to maintain access to the raw mail folders which contain the routing info and X-no-archive posts that web archives strip out. Another advantage to locating employees is that you can send them trojan executable attachments, which can be a very effective way into the network.

Next I'll gather known IP network information on the companies via DNS, whois, regional registries like ARIN, routing info, Netcraft, etc. Then comes the scanning (I tend to use Nmap), application-probing, vulnerability discovery, and exploitation stages.

Of course, I only do this when the company is paying me to do so. Performing these pen-tests offers several advantages over blackhat activity:

1. You don't go to jail (If you've worded your contract carefully.)
2. Instead of having to keep your übertechniques secret to avoid prosecution, you get to demonstrate them to management.
3. They actually pay you for this! And you are helping to protect them and the privacy of their customers.

Now some people might ask how you gain these skills without practicing on other networks first. Cheap hardware and the evolution of free UNIX operating systems have made this much easier than in the past. See the previous answer for some suggestions. And remember that you can always work together with friends, or participate in hacking contests like Defcon's Capture the Flag.

6) You'll have seen a lot of breakins.
by Hulver

During your time running Honeypots, you'll have seen a lot of compromised systems. Is there any incident that's really stuck in your mind because of the audacity of the attempt, or the stupidity of the person attempting the breakin.

Fyodor

On the humorous front, one attacker was was running a public webcam during his exploits, so we were able to watch him crack into our boxes in real time :). I will resist the urge to link a screenshot. His rough location was determined when we noticed Mrs. Doubtfire playing on his TV and correlated that with public schedule listings. He was working with a Pakistani group, but was actually on the US East Coast.

In the "disturbing audacity" front, this year we found that a group of crackers had broken into an ecommerce site and actually programmed an automated billing-sytem-to-IRC gateway. They could obtain or validate credit card numbers by simply querying the channel bot! Expect a more detailed writeup soon.

7) What makes a honey net enticing?
by cornice

It seems that many of the honey nets that the average hobbyist would run are built to attract a lesser cracker. What I mean is that ports are left open that normally would not be left open. Services are running that normally should not, etc. I think that a really smart fish would see this as nothing but a cheap lure and refuse the bait. Do you think it's possible to fool the really smart fish? Is is possible to bait with something enticing enough without tipping off the big fish? Does publication of your work make this task more difficult?

Fyodor

Excellent question, and I had many of the same concerns upon joining the project. Then I remembered that most of the attacks and real-world compromises are committed by these marginally skilled script kiddies. So there is still a lot of value in understanding their tools, tactics, and motives. Despite this apparent limitation, I have been surprised by some of the sophisticated things we have found. For example, the first known "in the wild" attack using the Solaris dtspcd vulnerability was caught by one of our honeynets and resulted in this CERT advisory. Then one of our Honeynet Alliance members had their Win2K honeypot compromised and joined into a botnet with 18,000 machines! Attackers on such a grand scale won't even know all of the companies they have compromised, much less whether any of the systems are honeynets.

I do believe baiting the "smart fish" might be possible, but I have never done this. Is not legally entrapment, as we aren't any sort of police force, but I am not very comfortable with the idea. If someone attacks my box that is just unobtrusively sitting on the network, I believe the attacker should have no expectation of privacy for his activities on the system. Things become more complex if I try to lure the attacker.

8) IPv6
by caluml

Do you think that with the very large address space of IPv6 that random scanning for a certain port will die off? (I notice nmap doesn't support random IPv6 address scanning - maybe you've already come to the same conclusion?) Simply put, the chances of finding a machine if it's not advertised anywhere will be very much reduced. Will this make people lazy and complacent, trusting on the large numbers involved to protect them?

Fyodor

Finding a machine by by pinging a completely random 128-bit address will probably never be effective. Fortunately, we won't have to! Nmap does not even do that for 32-bit IPv4 addresses - it is smart enough to skip huge blocks of address space that are unallocated or used for private (RFC1918, localhost) addresses. We will also see patterns emerge for IPv6. For example, they may often be allocated sequentially so that finding one leads to many others. I am waiting until adoption rises and we start seeing these patterns emerge before I can implement them appropriately in Nmap. Certain new DNS features may also prove useful for locating IPv6 machines and networks.

9) standalones and small home nets
by zogger

it seems like most of the emphasis is on enterprise networks, but that still leaves millions and millions of home machines and small home networks just stuck. What do you see as some of the trends and solutions for those people? Their data and system integrity is just as important to them as any corporations is, and usually not having the appropriate skill set, is even harder to implement.

Fyodor

I am afraid the focus by security companies on enterprise networks will continue, as that is where the money is. The good news is that securing small home networks is far easier. But that doesn't make it simple, nor mean that many people will bother. I would categorize the risks into 3 categories:

Traditional network server vulnerabilities: Your average home user doesn't need to run any network daemons or have any TCP/UDP ports open to the Internet. Most of the time they only have 1 IP, used either by a standalone PC or a NAT device (e.g. "broadband router") in front of their small network. This is a good configuration, as it limits what attackers can reach directly. But you need to be sure that the IP doesn't have any unnecessary ports open. You can verify this by running 'netstat' on the Windows or UNIX machine using the IP. I would also recommend confirming using a port scanner such as Nmap. Here are example commands:

nmap -p- -sS -T4 -v -O [your IP]
nmap -p- -sU -v [ your IP ]

The TCP and UDP scans could be combined into one execution, but are listed separately since the TCP scan may go much faster. Remote UDP scans are also less reliable against some heavily filtered hosts. You may have to rely on the netstat info or configuration details in this case.

Any open ports found should be evaluated with extreme prejudice. Unless clearly necessary, close Windows file sharing, external NAT device admin ports, and everything else found.

Don't forget the wireless backdoor! Blocking the Internet link from your private machines is insufficient if anyone can hop on your open WLAN and attack your machines. WEP isn't perfect, but the 104-bit (so-called 128-bit) version should at least keep people from accidentally connecting to your network or sniffing your data. Be sure to set a good password and upgrade to recent firmware for your WAP and other network devices.

Subscribe to the security advisory lists for all the operating systems (and devices, if available) you run. Major vendors such as RedHat, Debian, FreeBSD, Mandrake, and Microsoft all offer these. Most even offer automatic updates if you desire that.

Client vulnerabilities: Once you close the services you don't need (ideally all of them), client vulnerabilities must be addressed. Keeping your web browser and mail reader up-to-date is particularly crucial. Also harden them as much as possible. For example, IE is full of holes but at least has a good interface for site-by-site security policies (Tools -> Internet Options -> Security). Go through and neuter the "Internet zone" settings by disabling ActiveX and Java. In the rare case that sites need this, find an alternative site or add them to the trusted zone. If your are really serious about security, neuter "trusted sites" and "local intranet" privileges as well. Many recent IE vulnerabilities trick the browser into using the wrong zones. Consider using a different browser. Also configure your mailer to disregard HTML and JavaScript.

Remember to pay careful attention to security warnings, whether they come from IE, Mozilla, your ssh client, or anything else. Don't just click OK. And don't shoot yourself in the foot when configuring your apps. It is hard to entirely blame the vendor when users tell P2P apps or Windows filesharing to share their whole drive without any password. Failing to change default passwords or enable basic restrictions on X Window or FTP servers is only slightly more forgivable. All of these errors happen frequently! The apps/devices should be secure by default, but you have the ultimate responsibility for protecting your data.

Malware: This is what I consider the biggest problem on desktops: people running applications they can't trust. Email borne viruses, worms and trojans are an obvious example. Be very careful what you click on. Unfortunately, it is very difficult to know what to trust. Mail is trivial to forge, and even the "proper" installers for many P2P applications infest your computer with loads of invasive spyware. Even Intuit TurboTax was caught writing to customers' boot information track.

What can you do? My honest suggestion is to run peer-reviewed open source applications on a free OS such as Linux or FreeBSD. You still have to be careful, but these problems are far less prevalent on UNIX platforms, which also have better tools and procedures to deal with them.

What if dumping Windows is not an option? Run NT/2K/XP instead of Win9X/ME, and try to run everything you can as an unprivileged (non-administrator) user. Be extraordinarily careful about what you install and run, and make frequent backups. You might also want to look into a personal firewall such as Zone Alarm (limited free version.

10) What is your favourite tool?
by Noryungi

I have just read your top 75 security tools list. Thank you for posting all this information, which I am going to study very carefully.

One question though: in all these tools, which one is your personal favourite? (This excludes Nmap, of course).

Fyodor

I have far too many favorites among this great group to choose just one! But here are a few developers and tools that are particularly worthy of mention:

One of the people I most admire in the security field is Solar Designer. He is a guru in networking, security, and low level kernel/assembly/architecture details. He has also created many tools that security professionals use daily. Yet he never exhibits the arrogance, elitism, and egotism that sadly characterizes so many "stars" of the security community.

Among SD's tools is John the Ripper, my longtime favorite local password hash cracker. It has been around forever, but was written with a flexible and powerful interface while keeping extensibility in mind. So it is still as useful in these days of shadowed password files and MD5/Blowfish hashes as it was back in the days of crypt() and unprotected /etc/passwd. Lately SD has been working on the Owl secure GNU/Linux distribution, which can be installed on disk for hardened systems like firewalls, or booted and run from CD as an easy way to run security tools such as John and Nmap.

Another of those "brilliant yet still nice" security developers is Dug Song. Even after the seminal "Insertion, Evasion, and Denial of Service" paper by Ptacek and Newsham, many IDS vendors continued to ignore the problem. When Doug released Fragrouter (now fragroute), which implements some of these attacks, vendors finally took notice! He has also written the excellent libdnet library, but my favorite of his tools is DSniff, a suite of tools for advanced network sniffing and "monkey-in-the-middle" attacks. It even handles ARP poisoning and other techniques for sniffing hosts on a switched LAN.

While I'm on this topic, let me also give "mad props" to the Hping2 packet prober, Kismet wireless stumbler, Ethereal packet decoder, Netcat, recent THC releases, Snort IDS, the Nessus vulnerability scanner, and all the other great Open Source tools out there!

I would also like to thank Slashdot for granting me this interview and to everyone who asked such excellent questions. I only wish I had time to answer more of them. Then again, I have probably rambled on enough. Now it is your turn to ramble in the comments :).

Cheers,
Fyodor

You asked nmap creator Fyodor many excellent questions, and his answers (below) are just as excellent. You'll want to set aside significant time to read and digest this interview, because Fyodor didn't just toss off a few words, but put some real time and energy into his answers.

1) Interesting stories involving nmap?
by Neologic

Nmap has obviously become a huge success in the *nix world. I would wager that practically all sysadmins and security folk use nmap. With this sort of use by such creative and lazy people, there must have been some interesting stories involving nmap, perhaps unusual uses of it, or funny anecdotes. Are there any you would like to share?

Fyodor

The coolest use ever was undoubtedly when Trinity used it to try and save the human race :). But the use I find most gratifying are the Chinese students and residents who have written me about how they use Nmap to locate open proxies. These proxies allow for surfing the uncensored Internet, including the news, educational, pornographic, religious, open source software, government, political, search engine, and human rights sites that are blocked by the Great Firewall of China.

Many of the best features in Nmap came from the user community in ideas if not implementation. For example, the protocol scan (-sO) determines what IP protocols (TCP, UDP, GRE, etc.) a host is listening for. I had not thought of this, but the idea and patch came out of the blue one day in an email from Gerhard Rieger. On another day, a guy named Saurik sent a patch called Nmap+V that allows Nmap to do basic service/version fingerprinting against open ports. It has attracted a cult following, and I plan to add similar functionality to Nmap this year. The initial Windows port by eEye arrived similarly. Despite all these great suggestions, certain other user-contributed ideas are not on the agenda.

Then there are a small handful of users who detect problems nobody else would ever notice, like 4 byte/host memory leaks. They send me error messages with notes saying the bug happens "about once per 700,000 IPs". I have no idea what these guys are up to, but some have been sending me this kind of mail for years. They can't be spammers, as they are intelligent and also use more sophisticated scan techniques than you would need to just find SMTP servers.

2) Recent increases in anal-retentiveness...?
by Zeriel

There's been a marked increase in system administrators thinking that anything even remotely resembling a network scan is eeeeevil (case in point, last year I almost got kicked out of college for scanning port 80 on my dorm subnet looking for interesting websites to read)...

What do you think can be done to make scanning IP addresses/ports have less of a negative stigma? This is in the same sort of category as legit vs. illegit uses of anything else (P2P, whatever)--what's the rationale for punishing something that could maybe lead to criminal activity, and how can we make network scanning tools have practical uses again?

Fyodor

That is an excellent question, and one that concerns me as well. But first, I think your final statement is too extreme. I would guess 90% of network scanning is non-controversial. You will rarely be badgered for scanning your own machine or the networks you administer. The controversy comes when scanning other networks. There are a lot of (good and bad) reasons for doing this sort of network exploration. Perhaps you are scanning the other systems in your {dorm, department, cable LAN, conference LAN} to look for publicly shared files (FTP, SMB, WWW, etc.). Or perhaps your just trying to find the IP of a certain printer. Maybe you scanned your favorite web site to see if they are offering any other services, or because you are curious what OS they run. Perhaps you are just trying to test connectivity, or maybe you wanted to do a quick security sanity-check before handing off your credit card details to that ecommerce company. You might be conducting Internet research, or be bored on a rainy afternoon. Or are you conducting reconnaissance in preparation for a breakin attempt?

The remote administrators rarely know your true intentions, and do sometimes get suspicious. The best approach is to get permission first. I've seen a few people with non-administrative roles land in hot water after deciding to "prove" network insecurity by launching an intrusive scan of the entire company or campus. Admins tend to be more cooperative when asked in advance than when woken up at 3AM by an IDS alarm claiming they are under massive attack.

You compared Nmap to P2P tools in having a "negative stigma". In both cases, one effective way to fight the stigma is to limit your own use to "legitimate" purposes. Use BitTorrent to download RedHat ISOs, but not Matrix Reloaded. Use Nmap to secure and monitor your computers, but not to attack other networks. And if you decide to attack other networks anyway, please be courteous and set the evil bit.

Now I'll admit that I don't always obtain explicit permission before scanning other networks. I don't believe (but IANAL) that a simple port/OS scan of a remote system is or should be illegal. Any machine connected to the Internet will be scanned so often that most admins ignore such "white noise" anyhow. But scan other networks often enough, and someone will eventually complain. So my advice would be:

1. Don't do anything controversial from your work or school connections. Even though your intentions may be good, you have too much to lose if someone in power (boss, dean) decides you are a malicious cracker. Do you really want to explain your actions to someone who may not even understand the terms "port scanner" or "packet"? Spend $10 bucks a month for a dialup or shell account. You didn't really violate this rule, as scanning your dorm subnet for just port 80 should not even be remotely controversial!
2. Target your scan as tightly as possible. If you are only looking for web servers, specify -p80 rather than scanning all 65,535 TCP ports on each machine. If you are only trying to find available hosts, do an Nmap ping scan. Don't scan a /16 when a /24 will suffice. The random scan mode now takes an argument specifying the number of hosts, rather than running forever. So consider -iR 1000 rather than -iR 10000 if the former is sufficient. Use the default timing (or even "-T Polite") rather than "-T Insane".
3. Nmap offers many options for stealthy scans, including source-IP spoofing, decoy scanning, and the more recent Idle Scan technique. But remember there is always a trade-off. You will be harder to detect if you launch scans from an open WAP far from your house, with 17 decoys, while doing followup probes through a chain of 9 open proxies. But if anyone (such as Tsutomu Shimomura) does track you down, they will be mighty suspicious of your intentions.

I occasionally consider adding some sort of "notification packet" prior to a scan that would give hosts the chance to respond and opt-out. This would be like the /robots.txt directives currently used to control polite Web robots. Perhaps the format could even include a text string that IDS systems could log, like: nmap -sS -p- -O -m "Direct questions about this scan to ops at x3512" 192.168.0.0/16 nmap -sS -p- -O -m "mY n4m3 iZ Zer0 |<00L and I'll 0wn j0o%#@" targetcompany.com/24 Of course Nmap would have an option to omit the notification or to send it and ignore any negative responses. Some scanners, such as ISS Internet Scanner already send out NetBIOS popup messages to scanned hosts by default, and other scanners use syslog. I won't be adding any features like this to Nmap unless I see substantial demand and the obvious issues are worked out.

3) OS fingerprinting
by neoThoth

What are the latest advances in fingerprinting networked devices that seem most promising to you? I have started reading papers on HTTP fingerprinting and such and wonder how these will figure into the NMAP architecture. What are the most elusive OS's that aren't on the NMAP OS fingerprint database?

Fyodor

There are a number of OS detection techniques I hope to add this year. One is to guess (or calculate) the initial TTL of response packets, since this varies by OS. Some operating systems also "reflect" your own chosen TTL under various circumstances. Then there are some newer TCP options, such as selective ack that I might test for. Explicit Congestion Notification (RFC 2481/3168) also shows promise. I'll probably add all of these at once later this year, after discussions with the Nmap-dev list. If you wish to participate, you can join that list by sending a blank email to nmap-dev-subscribe@insecure.org. There is also a low volume, moderated list for announcements about Nmap, Insecure.org, and related projects. You can join the 15,000 current members by mailing nmap-hackers-subscribe@insecure.org [archives].

While adding new fingerprinting techniques is fun and exciting, improving the signature database often ads more value. The DB now contains more than 850 signatures, from the Acorn RISC OS and Aironet wireless LAN bridge to the ZoomAir wireless gateway and Zyxel Prestige routers. We're talking gaming consoles, phones, PBX systems, PDAs, webcams, networked power switches, you name it! New fingerprints are submitted daily.

Application level fingerprinting (including HTTP) is coming. I usually regret stating dates, but I hope to develop this functionality within the next 3 months.

4) Stepping into a network security career
by Anonymous Coward

I'll be graduating this month with a shiny new BS in Computer Science. I've done plenty of Unix sysadmin work throughout college and even deployed some high-interaction honeynets. I'm very interested in network security and systems programming. Do you have any advice for people in my situation who want to head into a career in network security?

Fyodor

Congratulations on your graduation! Unfortunately (for newcomers), the security field is one that often expects substantial experience and references. This is partly because these jobs require extraordinary trust, and also because of an aversion to mistakes. Everyone makes mistakes, but they can be extraordinarily costly in security and neophytes tend to make more of them. But don't lose hope! Talented security minds are still in very high demand, just be aware that you will have to work even harder to prove yourself.

Here are my suggestions for anyone starting out in network security, whether for fun or profit:

Step 1: Learn everything you can

1. You may wish to start with reading a general overview of security, such as Practical Unix and Internet Security 3rd Edition.
2. Reading alone won't teach you much. Hands-on experience is critical, so I would set up at least a basic test network. At the very minimum you should have a Unix box or two and a Windows machine (because these are very common in the real world). You can use very cheap machines, or even emulate a large network with virtualization software such as VMWare.
3. Next you should learn more about how attacks are performed. Take a look at the excellent and free Open Source Security Testing Methodology Manual (OSSTMM). This document aims to provide a comprehensive framework for security testing. But it mostly lists tasks to perform, without specifying how to do so. You will gain a lot from this manual if you research the tasks you don't know how to complete, and if you actually try performing the tasks on your test network. If this manual is too curt or hard to follow, you could try a more verbose book on vulnerability assessment, such as Hacking Exposed 4th Edition.
4. Now that you understand many of the general security ideas, it is time to get current. This is one area that has actually become easier in the last decade. The thinking used to be that vulnerability information should only be distributed to well-known and trusted administrators and security researchers through private digests such as Zardoz. This was a disaster for many reasons, and the full disclosure movement was born. In the last couple of years things have started to shift toward more limited ("responsible") disclosure and there is also a disturbing pay-money-for-early-disclosure trend. But information is still much more available than it used to be. Most of the news is carried on mailing lists, and I archive the ones I consider the best at Lists.Insecure.Org. You must subscribe to Bugtraq, and I would also highly recommend pen-test, vuln-dev, and security-basics. Read at least the last 6-12 months of archives. Choose other lists that correspond to your interests. SecurityFocus also offers a security-jobs list which is an excellent resource for finding jobs or just understanding what employers desire.

   There are two major reasons for reading Bugtraq. One is that you must react quickly to new vulnerabilities by patching your servers, notifying your clients, etc. You can get this by simply scanning the subject lines or advisory summaries for bugs that directly apply to you. But then you will miss out on another crucial purpose of Bugtraq. Actually understanding a vulnerability helps you defend against it, exploit it, and identify/prevent similar bugs in the future. When you are lucky, the advisory itself will provide full details on the bug. Check out this excellent recent advisory by Core Security Technologies. Note how they describe exactly how the Snort TCP Stream Reassembly vulnerability works in detail and even include a proof-of-concept demonstration. Unfortunately, not all advisories are so forthcoming. For bugs in Open Source software, you can understand the problem by reading the diff. The next step is to actually write and test an exploit. I would recommend writing at least one for each general class of bug (buffer overflow, format string, SQL injection, etc.) or whenever a bug is particularly interesting.

   Be sure to read the latest issues of Phrack and the research papers posted to the mailing lists. Send your comments and questions to the authors and you may start interesting discussions. Read well-regarded books on the security topics that interest you most.

   I can't emphasize enough that you should intersperse hands-on work with all of this reading. Install unpatched RedHat 8 (or whatever) and run Nmap and Nessus against it. Then compromise it remotely, maybe via the latest Samba hole. Start out with a prewritten exploit from Bugtraq, which isn't quite as easy as it sounds. You may have to modify the 'sploit to compile, brute force the proper offset, etc. Then break in again using a different technique, and your own exploit. Install Ethereal and/or tcpdump and ensure you understand the traffic on your network during both your exploitation and normal network activity. Install Snort on an Internet-facing machine and watch the attacks and probes you'll experience. Wander around your neighborhood with Kismet, Netstumbler, or Wellenreiter on your Laptop or PDA to look for open WAPs. Install DSniff and execute an active MITM attack on an SSH or SSL connection between two of your computers. Take a look at my Top 75 Tools List and ensure you understand what each does and when it would be useful. Try out as many as you can.

5. Take a vacation, or at least a weekend camping! You deserve it! The steps above would probably take at least 3-12 months full-time, depending on your motivation level and the depth and breadth of your research.

Step 2: Now apply your newfound knowledge

Now you have learned enough to be dangerous. At this point, you would have little trouble obtaining most certifications, after studying the specifics of each topic. If your main goal is to find a job quickly, perhaps adding these extra feathers to your cap might be worthwhile. But I think your best bet is to prove your knowledge by joining and contributing to the security community. While this does indeed help others, it isn't an entirely selfless act. It improves your skills, leads to important contacts, and demonstrates your knowledge and ability in a constructive way. The latter is important if securing a career is one of your goals. These steps should also be fun! If not, perhaps you should keep looking at other fields. Here are some ideas:

Start participating with insightful comment and answers on the mailing lists. This is very easy and serves as a great learning experience, way to meet people, and garners some name recognition. If a security manager with a stack of 60 resumes recognizes your name, that is a huge win!

When a new worm or a big new vulnerability comes out, everyone wants to know the details. If you stay up all night disassembling the worm/patch and write the first comprehensive analysis, many folks will find that valuable. And you will learn a lot. Let your first priority be quality - if someone beats you to it, just compare your results with theirs to see if you (or they) missed (or misinterpreted) anything. You can also post your own exploits, although that is more of a political hot potato.

Attending security conferences is a great way to learn, party with fellow hackers, and network (in every sense of the word). Much better is to speak at these conferences. This field changes rapidly so there are always new topics and technologies to discuss. You don't have to be a well-known expert with a long history - just learn your topic well and put in the effort for a quality presentation. You could present at Defcon, at one of the more commercial events, or at a smaller regional con like ToorCon, CodeCon, Hivercon, etc. Among other advantages (often free admission/travel/hotel), this is a great way to meet people with similar interests. I spoke at the latest CanSecWest and have submitted a proposal for the next Defcon.

Now that you've seen and understand a wide variety of software vulnerabilities from your Bugtraq research, start finding your own. You can start by downloading any PHP app from Sourceforge. Most of those are hopelessly vulnerable to Cross-Site-Scripting, SQL injection, and/or remote code execution by "remote include" directives. Many (if not most) Windows shareware daemons are also vulnerable to simple buffer overflows and format-string bugs. Notify the authors and then write an advisory. After a few of these "easy targets", try breaking some more widely deployed programs.

Write a security tool! I could list some suggestions, but by this point you will have many of your own ideas as to what is needed. Scratch an itch.

I hope this helps. If you want more suggestions, Ask Slashdot. From that story, I found this post particularly insightful, especially the emphasis on "people skills". I don't claim to have any, but understand the value :).

5) Have you ever been tempted to use your gifts...
by Tim_F

...in a negative manner?

Have you ever hacked into someone else's computer? Have you ever considered it? What would cause you to think of doing this? Would your tools (nmap, etc.) be enough to allow you to do this?

And if you haven't, why is that the case?

Fyodor

I never do script-kiddie style "hack any random vulnerable box on the Internet" cracking. But sometimes I will launch targeted attacks at specific companies. I'll usually start with just a web browser and various search engines to learn everything I can about my target. I need to understand what the company does, who it partners with, and whether it has any corporate siblings, subsidiaries, or parents. Beyond that, posts by individual employees can be a gold mine. Besides providing names and titles for social engineering and brute force password attacks, the IPs in the mail/news routing headers can be very valuable. One of the reasons I run my own mailing list archive is to maintain access to the raw mail folders which contain the routing info and X-no-archive posts that web archives strip out. Another advantage to locating employees is that you can send them trojan executable attachments, which can be a very effective way into the network.

Next I'll gather known IP network information on the companies via DNS, whois, regional registries like ARIN, routing info, Netcraft, etc. Then comes the scanning (I tend to use Nmap), application-probing, vulnerability discovery, and exploitation stages.

Of course, I only do this when the company is paying me to do so. Performing these pen-tests offers several advantages over blackhat activity:

1. You don't go to jail (If you've worded your contract carefully.)
2. Instead of having to keep your übertechniques secret to avoid prosecution, you get to demonstrate them to management.
3. They actually pay you for this! And you are helping to protect them and the privacy of their customers.

Now some people might ask how you gain these skills without practicing on other networks first. Cheap hardware and the evolution of free UNIX operating systems have made this much easier than in the past. See the previous answer for some suggestions. And remember that you can always work together with friends, or participate in hacking contests like Defcon's Capture the Flag.

6) You'll have seen a lot of breakins.
by Hulver

During your time running Honeypots, you'll have seen a lot of compromised systems. Is there any incident that's really stuck in your mind because of the audacity of the attempt, or the stupidity of the person attempting the breakin.

Fyodor

On the humorous front, one attacker was was running a public webcam during his exploits, so we were able to watch him crack into our boxes in real time :). I will resist the urge to link a screenshot. His rough location was determined when we noticed Mrs. Doubtfire playing on his TV and correlated that with public schedule listings. He was working with a Pakistani group, but was actually on the US East Coast.

In the "disturbing audacity" front, this year we found that a group of crackers had broken into an ecommerce site and actually programmed an automated billing-sytem-to-IRC gateway. They could obtain or validate credit card numbers by simply querying the channel bot! Expect a more detailed writeup soon.

7) What makes a honey net enticing?
by cornice

It seems that many of the honey nets that the average hobbyist would run are built to attract a lesser cracker. What I mean is that ports are left open that normally would not be left open. Services are running that normally should not, etc. I think that a really smart fish would see this as nothing but a cheap lure and refuse the bait. Do you think it's possible to fool the really smart fish? Is is possible to bait with something enticing enough without tipping off the big fish? Does publication of your work make this task more difficult?

Fyodor

Excellent question, and I had many of the same concerns upon joining the project. Then I remembered that most of the attacks and real-world compromises are committed by these marginally skilled script kiddies. So there is still a lot of value in understanding their tools, tactics, and motives. Despite this apparent limitation, I have been surprised by some of the sophisticated things we have found. For example, the first known "in the wild" attack using the Solaris dtspcd vulnerability was caught by one of our honeynets and resulted in this CERT advisory. Then one of our Honeynet Alliance members had their Win2K honeypot compromised and joined into a botnet with 18,000 machines! Attackers on such a grand scale won't even know all of the companies they have compromised, much less whether any of the systems are honeynets.

I do believe baiting the "smart fish" might be possible, but I have never done this. Is not legally entrapment, as we aren't any sort of police force, but I am not very comfortable with the idea. If someone attacks my box that is just unobtrusively sitting on the network, I believe the attacker should have no expectation of privacy for his activities on the system. Things become more complex if I try to lure the attacker.

8) IPv6
by caluml

Do you think that with the very large address space of IPv6 that random scanning for a certain port will die off? (I notice nmap doesn't support random IPv6 address scanning - maybe you've already come to the same conclusion?) Simply put, the chances of finding a machine if it's not advertised anywhere will be very much reduced. Will this make people lazy and complacent, trusting on the large numbers involved to protect them?

Fyodor

Finding a machine by by pinging a completely random 128-bit address will probably never be effective. Fortunately, we won't have to! Nmap does not even do that for 32-bit IPv4 addresses - it is smart enough to skip huge blocks of address space that are unallocated or used for private (RFC1918, localhost) addresses. We will also see patterns emerge for IPv6. For example, they may often be allocated sequentially so that finding one leads to many others. I am waiting until adoption rises and we start seeing these patterns emerge before I can implement them appropriately in Nmap. Certain new DNS features may also prove useful for locating IPv6 machines and networks.

9) standalones and small home nets
by zogger

it seems like most of the emphasis is on enterprise networks, but that still leaves millions and millions of home machines and small home networks just stuck. What do you see as some of the trends and solutions for those people? Their data and system integrity is just as important to them as any corporations is, and usually not having the appropriate skill set, is even harder to implement.

Fyodor

I am afraid the focus by security companies on enterprise networks will continue, as that is where the money is. The good news is that securing small home networks is far easier. But that doesn't make it simple, nor mean that many people will bother. I would categorize the risks into 3 categories:

Traditional network server vulnerabilities: Your average home user doesn't need to run any network daemons or have any TCP/UDP ports open to the Internet. Most of the time they only have 1 IP, used either by a standalone PC or a NAT device (e.g. "broadband router") in front of their small network. This is a good configuration, as it limits what attackers can reach directly. But you need to be sure that the IP doesn't have any unnecessary ports open. You can verify this by running 'netstat' on the Windows or UNIX machine using the IP. I would also recommend confirming using a port scanner such as Nmap. Here are example commands:

nmap -p- -sS -T4 -v -O [your IP]
nmap -p- -sU -v [ your IP ]

The TCP and UDP scans could be combined into one execution, but are listed separately since the TCP scan may go much faster. Remote UDP scans are also less reliable against some heavily filtered hosts. You may have to rely on the netstat info or configuration details in this case.

Any open ports found should be evaluated with extreme prejudice. Unless clearly necessary, close Windows file sharing, external NAT device admin ports, and everything else found.

Don't forget the wireless backdoor! Blocking the Internet link from your private machines is insufficient if anyone can hop on your open WLAN and attack your machines. WEP isn't perfect, but the 104-bit (so-called 128-bit) version should at least keep people from accidentally connecting to your network or sniffing your data. Be sure to set a good password and upgrade to recent firmware for your WAP and other network devices.

Subscribe to the security advisory lists for all the operating systems (and devices, if available) you run. Major vendors such as RedHat, Debian, FreeBSD, Mandrake, and Microsoft all offer these. Most even offer automatic updates if you desire that.

Client vulnerabilities: Once you close the services you don't need (ideally all of them), client vulnerabilities must be addressed. Keeping your web browser and mail reader up-to-date is particularly crucial. Also harden them as much as possible. For example, IE is full of holes but at least has a good interface for site-by-site security policies (Tools -> Internet Options -> Security). Go through and neuter the "Internet zone" settings by disabling ActiveX and Java. In the rare case that sites need this, find an alternative site or add them to the trusted zone. If your are really serious about security, neuter "trusted sites" and "local intranet" privileges as well. Many recent IE vulnerabilities trick the browser into using the wrong zones. Consider using a different browser. Also configure your mailer to disregard HTML and JavaScript.

Remember to pay careful attention to security warnings, whether they come from IE, Mozilla, your ssh client, or anything else. Don't just click OK. And don't shoot yourself in the foot when configuring your apps. It is hard to entirely blame the vendor when users tell P2P apps or Windows filesharing to share their whole drive without any password. Failing to change default passwords or enable basic restrictions on X Window or FTP servers is only slightly more forgivable. All of these errors happen frequently! The apps/devices should be secure by default, but you have the ultimate responsibility for protecting your data.

Malware: This is what I consider the biggest problem on desktops: people running applications they can't trust. Email borne viruses, worms and trojans are an obvious example. Be very careful what you click on. Unfortunately, it is very difficult to know what to trust. Mail is trivial to forge, and even the "proper" installers for many P2P applications infest your computer with loads of invasive spyware. Even Intuit TurboTax was caught writing to customers' boot information track.

What can you do? My honest suggestion is to run peer-reviewed open source applications on a free OS such as Linux or FreeBSD. You still have to be careful, but these problems are far less prevalent on UNIX platforms, which also have better tools and procedures to deal with them.

What if dumping Windows is not an option? Run NT/2K/XP instead of Win9X/ME, and try to run everything you can as an unprivileged (non-administrator) user. Be extraordinarily careful about what you install and run, and make frequent backups. You might also want to look into a personal firewall such as Zone Alarm (limited free version.

10) What is your favourite tool?
by Noryungi

I have just read your top 75 security tools list. Thank you for posting all this information, which I am going to study very carefully.

One question though: in all these tools, which one is your personal favourite? (This excludes Nmap, of course).

Fyodor

I have far too many favorites among this great group to choose just one! But here are a few developers and tools that are particularly worthy of mention:

One of the people I most admire in the security field is Solar Designer. He is a guru in networking, security, and low level kernel/assembly/architecture details. He has also created many tools that security professionals use daily. Yet he never exhibits the arrogance, elitism, and egotism that sadly characterizes so many "stars" of the security community.

Among SD's tools is John the Ripper, my longtime favorite local password hash cracker. It has been around forever, but was written with a flexible and powerful interface while keeping extensibility in mind. So it is still as useful in these days of shadowed password files and MD5/Blowfish hashes as it was back in the days of crypt() and unprotected /etc/passwd. Lately SD has been working on the Owl secure GNU/Linux distribution, which can be installed on disk for hardened systems like firewalls, or booted and run from CD as an easy way to run security tools such as John and Nmap.

Another of those "brilliant yet still nice" security developers is Dug Song. Even after the seminal "Insertion, Evasion, and Denial of Service" paper by Ptacek and Newsham, many IDS vendors continued to ignore the problem. When Doug released Fragrouter (now fragroute), which implements some of these attacks, vendors finally took notice! He has also written the excellent libdnet library, but my favorite of his tools is DSniff, a suite of tools for advanced network sniffing and "monkey-in-the-middle" attacks. It even handles ARP poisoning and other techniques for sniffing hosts on a switched LAN.

While I'm on this topic, let me also give "mad props" to the Hping2 packet prober, Kismet wireless stumbler, Ethereal packet decoder, Netcat, recent THC releases, Snort IDS, the Nessus vulnerability scanner, and all the other great Open Source tools out there!

I would also like to thank Slashdot for granting me this interview and to everyone who asked such excellent questions. I only wish I had time to answer more of them. Then again, I have probably rambled on enough. Now it is your turn to ramble in the comments :).

Cheers,
Fyodor

Eric Stats writes: "At one point in the not so distant past, Intrusion Detection Systems (IDSs) were network security applications reserved for Fortune 500 companies with enough IT budget to fork up the Big Dollar, or hard core packetheads willing to grep through tcpdump or shadow output. Over the past few years, a new pig on the block, Snort, has put that notion to rest. Instead of having to spring for hundreds of thousands of dollars for a feature-rich, state-of-the-art, IDS; open source fans now have an IDS that meets and beats most of the performance benchmarks and features of commercial, closed source IDSs. Jack Koziol's new book, Intrusion Detection with Snort, presents a comprehensive guide that those either novice to, or richly experienced with, the field of Intrusion Detection can use to get up to speed quickly on Snort." Read on for Eric's review. Intrusion Detection with Snort author Jack Koziol pages 400 publisher Sams rating 9 reviewer Eric Stats ISBN 157870281X summary Handbook on the open source Intrusion

What Koziol implies throughout Intrusion Detection with Snort, but never states outright, is that Snort holds an inherent advantage over closed source IDSs, in that the IDS itself can be tailored and customized for each individual deployment to a level not possible for closed source competitors. If you have had the displeasure of working with a rigid, uncustomizable, IDS you already know where this is going ...

In order for an IDS to be effective, or in some high-bandwidth cases, even usable, detailed network and business context must be applied to the IDS. In a nutshell, IDSs are not as plug-and-play as firewalls or other security applications. For example, if you know you are not running any HTTP traffic on the segment where the IDS is sniffing, you may not want your IDS to waste cycles looking for attacks on Apache. On the other hand, you may feel that the mere presence of HTTP traffic may indicate something innately suspicious, so it is of value to watch for any HTTP traffic. It all depends on what you feel are legitimate threats to the network you are attempting to protect. Snort gives you the power to "watch" for specific attacks, protocol anomalies, or other chatter that has no legitimate business running on your network. Other closed source IDSs don't, or can't, have the same flexibility. Only Snort can implement something as detailed as "Send a page to the CISO's phone if this particular subnet attacks these Apache servers with the chunked encoding exploit."

With Snort, novices can easily write attack signatures (called rules) enable or disable specific protocol decoders, and detect advanced attacks such as exploits utilizing polymorphic shellcode. Without this level of flexibility, you are likely to be flooded with alerts that are not relevant, or, even worse, miss an actual attack that causes irreparable data loss.

Like many open source applications, Snort's biggest downfall has been documentation. Who wants to write boring user manuals when he can write code, right? Well, that's all fine and dandy for Snort developers, but folks that want to actually use all of the neat features can't, unless you tell them they are there, and how to use them. Intrusion Detection with Snort bridges this gap, and offers a clear, concise, guideline that helps plan, implement and maintain Snort-based IDS.

Another oft-cited problem with Snort that Intrusion Detection with Snort addresses is the lack of Snort features that are not directly related to intrusion detection. In essence, Snort's developers have concentrated on creating the world's best application for detecting unauthorized activity, and left everything else to other applications. If you want to organize and manage the alerts generated by Snort you have to use another application (ACID). If you desire alerts via email or pager you need another tool (swatch or syslog-ng). If you want to centrally manage attack signatures for multiple Snort installations, guess what? You need another tool (IDS Policy Manager or SnortCenter). Finding, installing, and getting all of these tools to work right can be frustrating, so Koziol walks us through these issues, and in the end we have an IDS rivaling the expensive commercial solutions.

On to the nitty-gritty of the book. Essentially, this book is organized into logical three sections, even though the author did not choose to make these demarcations in print. The first section introduces us to intrusion detection in general and features of Snort. The second section is a detailed installation guide, which walks through setting up and installing the various components of a distributed Snort setup. The final section focuses on post-installation and maintenance tasks, as well as advanced topics.

In the first section, the different breeds of IDS (Host and Network) are honestly presented, Koziol acknowledging in great detail some of the major shortcomings of IDS technology. The book then moves to describing Snort in great detail in an unbiased fashion. Other books on this subject written by Snort contributors are less forthcoming with Snort's disadvantages. The inner workings of Snort (such as packet decoders and libpcap) and the largely undocumented preprocessors are described in detail, giving tons real world examples. The examples are somewhat current, and describe exploits commonly found 6-18 months ago. Although the actual exploits found in the wild may change over time, the strategies for discovering them with Snort should remain relatively constant. The book then moves into the activities required in planning for a Snort-based IDS installation. Some of this is common sense for experienced security practitioners, such as establishing an incident response plan (the "Oh shit, I've been hacked, what do I do now!?!?"), but is relevant for novices. Other topics introduced in this section are:

Sensor placement: where to place an IDS from a network design perspective for maximum benefit.

Inserting a sensor into an in place network: covers using taps, span ports, and dedicated hubs.

Specific hardware and OS considerations: basically, why a flavor of Unix is best for Snort.

Creating a unidirectional sniffing cable: allows network traffic to flow in a single direction, minimizing risk to an IDS segment.

The second section is a detailed guide to building a distributed or 3-tiered Snort IDS. Getting the three components, the sensor (where Snort is actually installed), the server (database, alert management, and reporting server), and the analyst console (secure place to access other components and store config files and scripts) up and working on Linux takes up the bulk of this section. The analyst console chapter walks through the ever-popular Analysis Console for Intrusion Databases (ACID). Attention is paid to configuring a secured setup that encrypts traffic between the various sensors, servers, and consoles. Various packages and tools are described, as well as condensing all of the Snort tiers onto one physical box. Installing and configuring on Windows is covered as well, although this choice of setup is not as thoroughly explained as the others. The third and final section picks up where most books that deal with a specific application or software package too often leave off, namely, keeping the damn thing working. A chapter is dedicated to tuning Snort, and what thresholds can be configured to maximize benefit and performance. Getting real-time alerting via email working with ancillary tools, is covered in a dedicated chapter. Developing a targeted ruleset (a set of automagically generated signatures that will only detect attacks that have the potential to be successful) using a custom shell script is described.

A very important topic in Snort administration, writing custom rules (attack signatures) gets its own chapter. The syntax for creating rules is clearly described, followed by concrete examples. The book works through writing rules by reading through raw packet captures (last year's Slapper worm is a particularly good example). This is followed by upgrading and managing rules, which is highly useful if you have a number of Snort installations to manage. Finally, Intrusion Detection with Snort closes with a chapter on advanced topics. The advanced topics chapter primarily covers the latest fad 'Intrusion Prevention.' Snort can be made into an IPS device via packet scrubbing or shunting. For packet scrubbing, the Snort Inline patch is used and the box is placed in between a trusted and untrusted network, dropping packets that match specifically created rules. Shunting is accomplished with SnortSam, which basically sends a request to a border router or firewall to block an attacking IP address for a predetermined period of time.

Overall Jack Koziol's Intrusion Detection with Snort is a viable text for learning Intrusion Detection with the worlds premier open source IDS, even if it is light on diagrams and pictures, but it still comes highly recommended from this reviewer.

You can purchase Intrusion Detection with Snort from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.

spring writes "Every so often, the author of everyone's favorite network reconnaissance tool, nmap, runs a survey to determine which security-oriented software products are most popular. This year's tool survey was just released, and it contains some interesting results. Old favorites like Nessus, Snort, Netcat, and Ethereal made the list, of course. SAINT and SARA are still around. But a number of new tools appeared this year, like Windows-only GFI LANguard, SuperScan, and Cain & Abel. Nikto and Kismet demonstrate the growing importance of wireless networks. The survey contains many good tools. Certainly worth a read."

Barkmullz asks: "I just recently finished yet another security review on the network at my place of employment. I designed the different security features from scratch and I am using a variety of devices and software (firewalls, IDS, DMZs, and so on). I like to look at network security with the same attitude as I look on the stock market: diversify. Don't put all your eggs in one basket. As I was pondering the review results I wondered what a completely unbiased observer would think of my security. I remember thinking that someone should start a radio show similar to James Cramer's RealMoney and ask the listeners: Are you secure? I am aware of what the NSA considers to be a secure network, but, honestly, who has read that stuff? What do you consider to be a secure network? What low-budget security features have you come up with? I don't think I am the only one spending evenings and weekends playing around with yet another IDS."

javifs writes "Do you remember TAMU's security tools? If so you might remember a tool that was developed when COPS, SATAN, and ISS were (back in 1994): Tiger. You might think it was dead, well it's not. Tiger has resurrected at Savannah and even has a new webpage and logo! (cool, isn't it?) Tiger has some interesting features that merit its resurrection, including a modular design that is easy to expand, and its double edge: an audit tool and a host intrusion detection system tool. Free Software intrusion detection is currently going many ways, however, from network IDS (with Snort), to the kernel (LIDS, or SNARE for Linux and Systrace for OpenBSD, for example), not mentioning file integrity checkers (many of these: aide, integrit samhain, tripwire...) and logcheckers (even more of these, check Counterpane's Log Analysis pages). Also, free software Linux/*BSD distributions have a miriad of security tools to do local security checks: Mandrake's msec, OpenBSD's /etc/security, SUSE's Seccheck... maybe Tiger could substitute them at some point in the future. Do you think Tiger has a place in the toolkit of the security professional? (I might be biased, though, after all I'm the upstream developer for Tiger now :-) ) In any case, have you downloaded and tested the latest release candidate for Tiger version 3.2?"

Jacob asks: " I have recently left a consulting/training firm to work in the public sector as a contractor. Part of my job functionality includes analyzing network traffic and security. This of course includes using products such as ethereal, snort, ntop and other network sniffers/analyzers. While working as a consultant I was legally covered by the company in which I worked for. Since I am no longer working for that company I do not have that same protection and I am worried about the possibility of being accused of 'sniffing passwords' or 'viewing confidential data' as a result of a normal network analysis. What is your experience in creating a legally binding contract or permission forms to perform network analysis and/or security audits?"

Sergei Egorov writes "Good people at Fidelis Security Systems developed SNORTRAN, an optimizing compiler for Snort rules. By combining several compilation techniques, SNORTRAN is able to translate a set of Snort rules into a high-performance intrusion detection engine. SNORTRAN-generated engines are 4 to 6 times faster than Snort's own detection engine; this translates into 3 to 5 overall speedup factor for a complete Snort system (benchmarks are here)."

jukal writes "Linux Journal has an article on using Snort as stealth sniffer, a stealth NDIS probe and stealth loger -- on a network interface with no IP address. 'Snort is a versatile and powerful tool for sniffing, intrusion detection and packet logging. Configuring it to run stealthily in sniffing mode or NIDS mode is easy; incorporating it into a stealth-logging solution is only slightly less so'"

Anonymous Coward writes: "Robin Miller, aka Roblimo, has written a great analysis of one of the first Open Source companies to be profitable before their IPO, Sourcefire! In this 'local boy makes good', we read about Team Fortress-playing programmer Marty Roesch, who writes Snort to beat his online gaming addiction. Now Snort is one of the most successful Intrusion Detection Systems out there and Marty's start-up is going gangbusters. Robin explains how Marty's company started in his basement (like Apple's garage), got profitable, then got venture capital in a time when everyone swears there is no venture. Marty even offers jobs at Sourcefire for the Slashdot crowd, 'Linux zealots, Open Source gurus, self-starters who are self motivating so I can just turn them loose...'"

Cally writes: "An interesting article appeared on the Info-Sec News list the other day about Guardent's new security appliance. Based on Snort, Nessus and IPTables, Guardent are taking the unusal step of trying to sell a product based on Free software into the highly resistant corporate security market. Although Free/Open security software is widely acknowledged to be better than commercial alternatives, it's rarely been trusted in the enterprise - the article points out that, although the NSA use Free software, the need for an expensive government audit prevents the government from saving money and improving security."

Swannie asks: "The company I'm working for is looking into Intrusion Detection Systems. I was curious on how good/bad/ugly/cute/cuddly LIDS (Linux Intrusion Detection System) is when compared to other, commercial, systems like Cisco's NetRanger, etc. I'd be interested in information from my fellow geeks that have deployed LIDS in real world situations, as well as anyone that has switched to LIDS from a commercial solution, or vice-versa. Hopefully if I have some ammunition to go to the powers that be, I'll be able to utilize an open-source (and less expensive) Linux solution instead of a more expensive commercial one." Are there any other options out there which can be added to this comparison? In an odd bit of synchronicity, this article popped up before press time, which offers up another possible answer, in the form of Snort.