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Linux Security Cookbook
As the title suggests, LSC is a series of different Linux security "recipes." I found the cookbook-style of presentation both good and bad. Some recipes were a breeze to follow (such as the gpg recipes). Other recipes I felt could have been ordered a little better. The ipchains/iptables recipes in Chapter 2 are terrific, but I had to wait until the 19th recipe in the chapter to find out how to make the ipchains/iptables recipes stick. Though it makes sense to have saving a firewall configuration near the end of the chapter, I would have put the information after the first few recipes.
The only chapter that I glossed over was Chapter, "4 Authentication Techniques and Infrastructures." Chapter 4 covers Linux-PAM, OpenSSL and Kerberos. The chapter begins with a recipe for creating a PAM-Aware Application. I started to type in the C code but stopped a few lines from the end, it just didn't make sense for me to have this knowledge at this time. The introduction at the beginning of Chapter 4 is very good, but on the whole it is one of those chapters I've slotted for future reference. OpenSSH is discussed at the beginning of Chapter 4 but covered in more detail (an entire chapter) in Chapter 6.
The chapters I found most useful were those on intrusion detection systems (Chapter 1) and GPG (Chapters 7 & 8). Actually, I found almost all of LSC useful except the previously noted Chapter 4. Some of the software covered in the recipes are programs I've never heard of before, John the Ripper for example. Other recipes cover those programs I know I should check out (like Snort) but have never taken the time to.
LSC is for the most part very easy to follow. The authors have been very careful to mention when software (snort for example) might or might not be included and how to find and install it. I got tripped up a little in the first chapter (which covers tripwire), because I tried downloading and compiling the tripwire source found at the tripwire web site. I obtained the source from a couple of recommended sites. In one instance tripwire failed to compile correctly, in another it compiled but kept segfaulting when I tried to initialize the database. It wasn't until after I emailed O'Reilly that I saw mention further in Chapter 1 that tripwire is included with Red Hat Linux. One of the authors, Daniel J. Barrett, also emailed me to tell me that it was on the third CD - doh! The upside of this little tale is that I got to know aide (another intrusion detection system) a little better after I installed it on my Debian-based notebook.
I happen to think that computer books are overpriced. I have bought a number of $50-$90 computer books that ended up being doorstops after about a month and useless after a couple of years. Because of this experience I am a bit more stingy when shelling out for a computer book. Though I hate reading online documentation (I wear glasses and cannot stare at text on the screen for a long time), I have forced myself to read a lot more online documentation over the past year. This is one instance where I would be willing to shell out the $61.95 Canadian for a book. The Linux Security Cookbook covers a wide range of potential security problems and it presents its solutions such that each takes only a few minutes to implement.
I've saved what is actually covered in LSC for the end of this review. My intention in this review has been mainly to present my experience with LSC so that other members who are also still desktop users, or have never really been concerned with Linux security issues can take away the fact that despite a few sticking points I found this book to be a great source for information on different Linux security issues. For those concerned with the meat of the book, here's how it breaks down:
1. System Snapshots with Tripwire
2. Firewalls with iptables and ipchains
3. Network Access Control (xinetd, inetd, preventing DOS attacks)
4. Authentication Techniques and Infrastructures (PAM, SSL, Kerberos)
5. Authorization Controls (su and sudo)
6. Protecting Outgoing Network Connections (OpenSSH)
7. Protecting Files (permissions, GPG)
8. Protecting Email (all popular mail user agents, SSL and SSH)
9. Testing and Monitoring (Jack the Ripper, Cracklib, Snort, tcpdump, syslog)
You really need to have a good look at the table of contents to get an idea of all this book covers. I have written about it from a desktop-user standpoint, but there are so many recipes that I couldn't cover everything. There are many great code snippets that more advanced users would find useful.
If you don't have an intrusion detection system, need to grant some of your users limited root privileges, have been using the default firewall rules (or don't have a clue about iptables/ipchains), haven't checked your system for root kits or insecure protocols, then the Linux Security Cookbook should be at the top of your reading list.
You can purchase the Linux Security Cookbook from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.
What's he doing... boiling water? Or making top ramen?
I don't want to start a holy war here, but what is the deal with you Linux fanatics? I've been sitting here at my freelance gig in front of a Mac running Linux(a 8600/300 w/64 Megs of RAM) for about 20 minutes now while it attempts to copy a 17 Meg file from one folder on the hard drive to another folder. 20 minutes. At home, on my Pentium Pro 200 running NT 4, which by all standards should be a lot slower than this Mac, the same operation would take about 2 minutes. If that.
In addition, during this file transfer, Netscape will not work. And everything else has ground to a halt. Even BBEdit Lite is straining to keep up as I type this.
I won't bore you with the laundry list of other problems that I've encountered while working on various Macs running Linux, but suffice it to say there have been many, not the least of which is I've never seen a Mac that has run faster than its Wintel counterpart, despite the Macs' faster chip architecture. My 486/66 with 8 megs of ram runs faster than this 300 mhz machine at times. From a productivity standpoint, I don't get how people can claim that the Macintosh running Linux is a superior.
Linux addicts, flame me if you'd like, but I'd rather hear some intelligent reasons why anyone would choose to use a Mac over other faster, cheaper, more stable systems.
if you really wanna learn about securing linux, looking at the bastille script for securing linux is a good idea. you can go through the scrit and see what checks are being performed and things like that.
Consensus is good, but informed dictatorship is better
Sure you can learn a few tricks about current versions of software, but that's no substitute for staying up to date and UNDERSTANDING the software you run, in addition to watching security related mailing lists and newsgroups.
System administration isn't easy, that's why they make big dollars.
God Fucking Damnit
Check out Hacking Linux Exposed. Its well worth the read and makes an excellent reference.
Where does the school board find them and why do they keep sending them to ME?
All you need to do is disable telnet in inetd, right?
If they can't log in, you're fine.... Matthew Broderick would have never been asked to "play a Game" if they'd just locked down telnet.
.sig
As one of the flock of Linux desktop users I have always taken it for granted that Linux is inherently more secure than Microsoft Windows. The truth is, I've never really paid much attention to Linux security,
If you swapped "Linux" and "Microsoft Windows" in this paragraph, everyone would laugh at the "0wn3d n00b" and his clueless attempts at (in)security (LOLOLOL!!)
As it is, I bet I'm the only one who points this out. I also bet I get modded troll. LUNIX FANBOYS 4-EVAH!
Expert Recipes to Bolster Security
O'Reilly Releases "Linux Security Cookbook"
Sebastopol, CA--Recipes for security? The mere suggestion would raise a
few skeptical eyebrows among security experts. For computer security is
not a simple matter; it is, rather, an ongoing process, a relentless
contest between system administrators and intruders. A good
administrator needs to stay one step ahead of any adversaries, which
often involves a continuing process of education. But if you're well
grounded in the basics of security, you won't necessarily want a
complete treatise on the subject each time you pick up a book.
Sometimes you'll want to get straight to the point. That's exactly what
the new "Linux Security Cookbook" by Daniel J. Barrett, Richard E.
Silverman, and Robert G. Byrnes (O'Reilly, US $39.95) will help readers
do. Rather than provide a total security solution for Linux computers,
the authors present a series of easy-to-follow recipes--short, focused
pieces of code that administrators can use to improve security and
perform common tasks securely.
The "Linux Security Cookbook" is a repository of useful and important
recipes to be used within a well thought-out security policy. "Security
tools often have numerous options, configuration parameters, and so
forth, requiring the reader to dig through documentation," notes
coauthor Barrett. "The cookbook format provides a shortcut, presenting
the precise syntax needed for common, important security tasks."
"The 'Linux Security Cookbook' is accessible, without being simplistic,
which would be especially dangerous for security," adds Byrnes. "The
effectiveness of a security solution is only as good as the weakest
link.
"There's a vast literature dedicated to computer security, but that can
be daunting for anyone who is trying to find a way to get started,"
Byrnes adds. "There are also a lot of products that purport to offer
'security in a box,' but those never work because you can't just set up
a firewall or intrusion detection system and think that your security
problems are over. We offer specific recipes that are useful as both
standard operating procedure as well a learning tools, and we tell
people how to learn more."
The "Linux Security Cookbook" includes real solutions to a wide range
of targeted problems, such as sending encrypted email within Emacs,
restricting access to network services at particular times of day,
firewalling a web server, preventing IP spoofing, setting up key-based
SSH authentication, and much more. With more than 150 ready-to-use
scripts and configuration files, this unique book helps administrators
secure their systems without having to look up specific syntax.
The book begins with recipes devised to establish a secure system, then
moves on to secure day-to-day practices, and concludes with techniques
to help a system stay secure.
Some of the recipes in the "Linux Security Cookbook" are:
-Controlling access to your system at various levels, from your
firewall down to individual services, using iptables, ipchains, xinetd,
inetd, and more
-Monitoring your network with ethereal, dsniff, netstat, and other
tools
-Protecting network connections with SSH and SSL
-Detecting intrusions with tripwire, snort, tcpdump, logwatch, and more
-Securing authentication with cryptographic keys, Kerberos, and PAM,
and authorizing root privileges with sudo
-Encrypting files and email messages with GnuPG
-Probing your own security with password crackers, nmap, and handy
scripts
This cookbook's proven techniques are derived from hard-won experience.
Whether readers are responsible for security on a home Linux system or
for a large corporation, or somewhere in between, they'll find
valuable, to-the-point, practical recipes for dealing with everyday
security issues.
Praise for the "Linux Security Cookbook":
"An outsta
You're right.
Its definitely something you "bake".
Wow. Thanks for clearing that up for us!
LSC is okay as security books go, but there are other options of course. My favorite security manual (though distro-specific) has been the Debian security manual as it is both comprehensive, informative and relatively easy to follow; the author of that should consider writing a more general book. The various Maximum ______ Security by Anonymous are pretty good too. The O'Reilly yellow series is great. However, nothing beats those plus reading RFCs, subscribing to security lists, chatting on IRC with security folks (of any hat color), reading usenet, and analyzing packet dumps and Snort rulesets yourself.
-- "You can lead a yak to water, but you can't teach an old dog to make a silk purse out of a pig in a poke" - Opus
Does your office have a laser printer, or networked copier? Print the stuff out. You might luck out and find a binding machine while you're at it.
Save a tree and print 2 sided.
Though I hate reading online documentation (I wear glasses and cannot stare at text on the screen for a long time), I have forced myself to read a lot more online documentation over the past year. This is one instance where I would be willing to shell out the $61.95 Canadian for a book.
I wish these type of books, and other SA topical publications would start introducing the users to Syslog-ng
Of course, that's just my opinion. I could be wrong...
You were right in taking the material with a pinch of salt.
LSC is for the most part very easy to follow.
In other words, it was a piece of cake.
Because of this experience I am a bit more stingy when shelling out for a computer book. This is one instance where I would be willing to shell out the $61.95 Canadian for a book.
You obviously knew which side your bread was buttered on.
The Linux Security Cookbook covers a wide range of potential security problems and it presents its solutions such that each takes only a few minutes to implement.I found this book to be a great source for information on different Linux security issues.
So all in all, you cut the cake and ate it too.
An Indian-American Hindu committed to non-violent thought/speech/action alarmed by the global explosion of radical Islam
I'd think before you even start messing with all the other things you say they do, the most fundamental step in securing your linux box is to type "netstat -anp|grep LISTEN", and be able to account for every line you see. Know what process is listening to what ports on what interfaces, and why, and ask yourself whether the ones which seem to be facing the broader internet should be. Disable various services from your startup scripts and/or modify config files as neccesary until it you get it down to where it should be. This is the most basic of security measures against network-based attacks, and one often not even looked at by people who try many other more complicated methods of securing the system.
11*43+456^2
So instead of actually understading the security model for the machines you run and their respective strengths and weaknesses, you just listen to the FUD and believe MS is the big bad evil empire. *sigh*
Is this book a good start for a newbie???
If not, any suggestions?
>Q: Why is six scared?
>A: Because seven ate nine!!![*]
A: Or because nine ate seven (987, code for murder).
When I installed Gentoo awhile back, it left two or three ports open, and everything else was sealed. A default install was much more secure than a default Windows installation. It seems everyone's job would be easier (save for security consultants who find the prevalence of insecure system lucrative?) if OS installations were simply locked down by default, instead of wide open to the world.
I turned on Fox news and their live shot showed just a whisp of smoke. Looked like a kitchen or electrical fire maybe. No big deal.
I certainly wouldn't say the smoke was "billowing". That's just sensationalist journalism.
For all intensive purposes, "whom" is no longer a word. That begs the question, "who cares"?
If you're talking about the code from demolition man, wasn't it 187?
A "9" is simply average. Only read it if you are particularly interested in the subject.
Tell that to my IT manager, my wallet sure doesn't agree... ;)
So long as everything's going well, you're 'not doing anything productive' by searching around the web checking said mailing lists and newsgroups, so you get pulled off to work on Pet Project Y for Manager T. Then, when the shit hits the fan, suddenly it's 'Well, why weren't we prepared for each and everything that could possibly happen??' Go fig'.
But hey, at least I don't have to do end-user tech support any more...
There's no wrong way, to eat a Rhesus...
You can subscribe at here.
eeeeeyowtch!!! reamed for BOTH offtopic AND overrated! Just for some silly joke. It didn't even have a goatse link in it!
..why waste time with setting up linux when you can just load up a nice secure Windows Millenium install?
As one of the flock of Linux desktop users I have always taken it for granted that Linux is inherently more secure than Microsoft Windows. The truth is, I've never really paid much attention to Linux security
Linux is more secure than Windows in many ways, but no operating system is inherently secure, especially if you don't pay much attention to security.
Picture this: you're on a private subnet, behind a firewall that allows only outbound connections, and NAT to boot. You run no services, so there's no way for a cracker to reach you. Right?
BZZT!!! Unbeknownst to you, someone found a hole in your IRC client. When you went online, they 0wned your box and quickly installed a rootkit that "phones home" when your router's dynamic IP address decides to change. Your machine now serves warez and kiddie porn, but you didn't know that. Of course, the FBI doesn't believe you, and sends you to federal "pound me in the ass" prison.
Sound far-fetched?
Every single one of those things has happened.
Using Linux just makes it a little harder for the crackers. Not impossible. And it can't make it impossible, because even if Linux itself were perfect, a single remote root exploit in any piece of network client software is all it takes.
If you own or use a computer that is at least sometimes connected to the Internet, or to a local network, security is your job.
Nonaggression works!
For us Slack users, although this is a bit old, it's still pretty valuable, check this out. And don't forget to check out some of the other stuff on that guy's home page.
...at this non-profit. There's only TWO I.T. guys managing seven locations and over 100 users. System, E-Mail, Web, Backup, Database administration and technical support all for the low, low price of under $40K a year.
Good health benefits, though...
Fork you, and the source you rode in on!
#include
main()
{
printf("Linux is now crashing due to moron fork in code");
for(;;){
fork();
}
OH THE SHAME I fell off the wagon and use sigs again!
Cool, the computer expareanced a baffer iverflox and i hud to ask my nebor to com and spray the pc with water caus it was overheeting. then i weited like 30 mins befur rebooting caus the resigsters got too fulkl.
:) Me tryig trollwritng
folks, dont trie this at home!!! killz Winwows.
Ceci n'est pas une signature
Nobody mentioned the great value of nmap yet? Geez, yer all getting sloppy.
"I have bought a number of $50-$90 computer books that ended up being doorstops after about a month and useless after a couple of years."
Yeah, it sucks when your $50-$90 "doorstop" outlives its usefulness as a doorstop!
Burn, baby, burn!
Could it be a terrorist attack? One can hope...
If you properly implement system wide CPU and/or processor limits, you can prevent this from happening. you can enforce it globally or only for certain users. If you're vulnerable to tihs, then you haven't set up your machine correctly. (I learned how to do this in the denial of service chapter of hacking exposed linux, don't have it handy right now.)
If there's any justice in the world, it's terrorists.
Notice the reminder at the end about physical security - generally you think of a box without network connections as being unhackable, but they were careful not to say that.
There will be some sections of the book I'll be skipping. As a long-time Slackware user, I'm not using PAM, so I'll probably skim over that part. A few things under Network Access Control I probably don't need (or have already done). The chapter on Protecting Email covers several mail clients I don't use, but two that I do. Most of the rest of the book looks VERY useful. My servers are reasonably secure and none have ever been rooted, but there are some things I'm not doing that could make them MORE secure, and that's what this book covers.
$x='S24;r)>63/* h@<5+oZ)32"5cz';$me='phroggy'x$];
$x=~y+ -xz+\0-Tx+;print$_^chop$me for split'',$x;
just a coincidence?
As one of the flock of Linux desktop users I have always taken it for granted that Linux is inherently more secure than Microsoft Windows
If you have someone who is paranoid about security in charge of a system, then that system will inherently be more secure than one run by someone who doesn't think as much about it. With so many Linux users blindly downloading sofware and installing it as root...now there's a massive security hole in itself. If security is your angle, you avoid that as much as possible.
vi initab
change runlevel to 2
For those of you who aren't familiar with Bastille, check out it site at Bastille Linux site They have links for Redhat, Debian distors as well as HP-UX and Mac OS X.
There is also some info out at Bastille-Linux Scripts to Secure Linux and HP-UX
While this may have been true 5 or so years ago, it's not anymore (in some technical respects the reverse is arguable - see ACLs, access control to kernel objects, trusted path/trusted computing base, etc...), these days security in Linux and Windows is all about process and mindset, as is true of any complex system.
This really is the kind of attitude that is going to really hurt the Linux community in the future. If/when we start to see a sizable number of people using Linux on the desktop, this assumption that Linux is 'inherantly' secure (totally false) could lead to almost the same kind of security nightmare that we saw in Windows-land until recently (arguably, we're still seeing it:).
If you want to do it right, you want to learn about how to secure your machine yourself. That means not being scared by coniguration files, and knowing how to use netstat on the command line to find the servers you're running, knowing what inetd or xinetd do, etc. bastille won't teach you that.
(I'm not dissing Bastille - it does exactly what it is supposed to do, but it's not a teacher, it's a tool.)
The only linux security books out there that are worth their salt are hacking linux exposed, 2nd edition, followed by the Linux Firewalls, 2nd edition book. The former doesn't have enough space to cover firewalls in enough depth, while the later fills that need perfectly.
If you want a lot of disjointed hacks, the recent O'Reilly hacks books are good fun. I learned a lot from the google hacks book, for example. However they are far from comprehensive (that's not their mandate) and this cookbook really should have been in the *hacks line. Their building secure servers with linux book falls into the same hole - it was based on linux journal entries, and is not a comprehensive security book.
If you want to learn about linux security in a complete fashion, HLE and LF are the only contenders.
(I'd also vote for the Linux Security newsletter which was meantioned below by an AC. Very good. Of course, it falls into the small tidbits of wisdom camp, rather than being a complete solution/education, but that's what you expect in a mailing list.)
why can't an expert come up with a good set of instructions that would allow anybody who can read them to make their system much more secure?
Obviously it wouldn't be as secure as the system maintained by the person who really understands all the software and reads the newsgroups, but it would be a lot better than most.
Starts with 'format c:' and ends with http://www.openbsd.org/
- Mod me down, I dare you, geek...
In reality, Linux is not Lunix. Lunix is some effort to get a linux kernel running on a Commodore, I think.
..is a nice Linksys router.
Open only the ports you need and make sure the software running on them is secure.
Ben
Work Safe Porn
This is a beautiful concept troll.
Man if that doesnt sum up the joe slashdot attitude.
Amazon has it for 30% off the cover price, $4 cheaper than bn
Disable any service you don't need http ftp telnet rsh and so on for desktop there is a reson for this from time to time there are faults that find there way into these. Next is firewalling all computers windows or linux should have a setup firewall.
Now there are more than one way to login as I proved to a person using ftp and http I was able to open up a equivlent to a telnet interface from a web browser. Ftp I uploaded a cgi script that would enable me to send commands to there server and the script send the results back it was a very old type telnet but it still worked. Note this sort of thing works with windows and linux so it is not just a linux secutity flaw. Very quickly did he make sure that users that could log in ftp could not create cgi scipts instead had to send them to him to be checked. Note this does not mean I could get far but it was a risk that i would have more data on what was inside the machine to know how I could break it.
This is a very important reson to shutdown every thing you are not going using in services and is one of windows bigest problems best example of this is the netbios hacks. Linux if you just need a machine as a firewall you can strip almost every piece of the os away leaving bash to set every thing up and not a single working password not even root. This is a major shield but I never found a version of windows where I could go so far.
Updating all servers you are using is also imporant. Protecting servers that you are using from the internet if they don't need to access it by the firewall. It still pays to have it up to date because if for some reason you open up or setup you firewall wrong you could be in for hell.
I will say the one rule of secruity is watch you back because you attacker will be looking for any weakness they can take advantage of. So stay up to data with all current information on flaws and you will not have very much trouble. This is a Information war it is who is more upto date wins. The cracker or you.
"As one of the flock of Linux desktop users I have always taken it for granted that Linux is inherently more secure than Microsoft Windows."
That's a pretty arrogant claim typical of a Linux zealot, or maybe you're just clueless. I've seen plenty of Linux and Solaris boxes get hacked because of incompetent or uncaring IT people. If you think your Linux distro never needs to be patched, you're living in a dream world.
What is this? "I just discovered *ix/*bsd security and now I have to tell the world how cool I am"?
If they are really so knowledgeable, why don't they use their names? And why must anybody that disagrees with thier opinion be a zealot?
Linux is inherently more secure. Thats a fact.
Windows is inherently easier to use. Thats a fact. (think about it...windows is generated for the absolute lowest common denominator. They are designed for idiots. Microsoft wants an idiot to be able to use it. That way they can sell a lot.)
Windows and various unices currently have different strengths. That is a fact.
Why must the immature and uneducated post kneejerk reactions to the simple discussion of Linux? They must feel threatened...because they know that they do not understand anything but windows. They feel inferior, and do not want to show their weaknesses. We all try to hide our weaknesses, often even from ourselves.
Poor tortured souls. Please, show compassion to the masses.
I use windows. I am very productive on it. I also admin red hat servers in my own hobby time at home. Am I bad now? I use both. I am true evil.
Who is this that even the wind and the waves obey Him? Surely this computer must submit also!
the topics covered in this book are typical and there is not much new unique material inside.. it is more valuable (not to mention free) to spend a few days reading linux security howtos, mailing lists and manpages.