Slashdot Mirror
Obsession With Firewalls Could Hinder IPv6
DosIgriegas writes "The obsession with firewalls in IPv6 may result in some of the quirks of IPv4 reappearing. Ars Technica has an article looking at the topic in depth, exploring the technical challenges of securing the new protocol, and looking a the re-emergence of old problems in new guises. 'Ironically, what's required to make IPv6 work through a stateful firewall is almost identical to what's required to make IPv4 work though NAT. This means the IETF's efforts to keep IPv6 NAT-free in order to make protocols do their job without messy workarounds are defeated by the notion that everything should be firewalled.' If we decide to stick with firewalls in IPv6, we'll see many of the same hard-to-diagnose network problems that we have with IPv4."
So, they're saying the way to get security in IPv6 is to throw away the whole concept of firewalls and hope that the protocol won't leave us with out collective bums hanging out in the wind??
I can't see a widespread adoption of a protocol that wants to get rid of firewalls. Now, I guess it's entirely possible that the IPv6 would secure networks since I'm not really up to speed on it's details. But I'm going to need an awful lot of convincing before I put any machines onto a network without something physically between me and it.
Unless IPv6 is very different, the only way I'm going to be able to set up my own personal network (and secure it) is with NAT. I'll take 'hard to diagnose' over pwn3d any day.
This just sounds so wrong.
Cheers
Lost at C:>. Found at C.
You can have a firewall that does not use NAT. Both sides are publicly addressable but there is still a security device between you and the outside world.
"I use a Mac because I'm just better than you are."
Is it a good idea to expect that whenever and wherever a mobile computing device connects to a network, there will be a properly configured firewall ready to protect it, or should computers and other networked devices be able to function securely without an external firewall to protect them?
Its a nonsensical situation that operating systems in general cannot be relied upon for the security of their own network interfaces - after all it is down to the operating system to accept or reject user logins. In the same way it should be the operating system that sets policy about whether to accept or reject packets from arbitrary locations.
A firewall is roughly equivalent to a plaster on an open wound - it serves a useful purpose, but nobody should expect to walk around with an open wound on a long term basis.
There is little if anything that a firewall can do that an operating system can't.
SURELY NOT!!!!!
I would say I personally am not obsessed with firewalls per se, I'm obsessed with privacy and security.
The firmware on a firewall also has a much smaller amount of code to debug in order to make sure that it will function properly all the time. I would never assume that my Windows XP machine was properly patched with enough confidence to plug it straight into a cable modem all the time.
I am also not interested in having each computer in my home being identified and tracked individually, and I don't pirate software or download music. As such, even if the need for NAT is removed, I would still be highly interested in purchasing a device to block incoming connections and mask my IP address (maybe by swapping with other devices within my home on certain connections).
It seems strange that people are arguing about getting rid of NAT devices and having unique IPs for every device without bringing up the privacy implications. It seems that having unique addresses for every device is a small step away from being able to track and monitor every device on the net. Without the ability to proxy or perform NAT services, every device would be exposed to the net, and would leave a reliable trail of activity. It seems that this would encourage governments to think that they can control and enforce the web, and deal a pretty strong blow to the level of anonymity granted by the current network topology. I just hope that if this does come to pass, that there will be solutions to mitigate this risk, to help obfuscate individual activity on the net. This hazard to troubleshooting network issues, as described in the summary, might be an important factor in ensuring privacy and a certain degree of anonymity on the web.
"I like systems, their application excepted", George Sand (French)
The problem was that NAT makes connections somewhat hard to deal with. IPV6 was designed to solve that problem. The problen now is that we realize that computers are vulnerable and need protection. IPV6 was not designed to solve that problem, and furthermore, it's not a problem which is likely to be overcome using technology or a new protocol.
This isn't about NAT, it's about firewalling (blocking ports). You can have a firewall without NAT, but apparently allowing firewalls allows NAT too. Since NAT is bad design, and as you say unnecessary, we'd like to disallow it at the protocol level. However if you do that, you can't have a firewall which is a problem for some people. IMO, firewalls are bad design too. Close the ports you don't need, and use ACLs to limit access to the ports you do.
Sort of. By definition, a stateful firewall probably has the capability of performing NAT, but there's no reason why you'd want to, if you have enough external addresses for everything on your network.
I don't think that NAT is "disallowed at the protocol level," as much as just rendered unnecessary. You could still build an IPv6 NAT box, if you really wanted to, but it would be a bit stupid. It's like building a box that hides two Ethernet cards behind one MAC address -- sure, you could do it, but since they both already have unique identifiers, why would you want to? There's no shortage. (Okay, that may not be the best comparison in the world, but you get the idea.)
NAT is driven by a shortage of routable IP addresses. With v6, there's no longer a shortage. However, people are still going to want the security offered by stateful firewalls (NAT, in its most trivial 1:1 implementations, doesn't offer any security -- it's all in the firewall anyway), which if configured incorrectly or overzealously, could create almost as many problems themselves as NAT does currently.
However, I still think that IPv6 is a big improvement. Why? Because with v6, you have the option of not using the stateful firewall, on devices that are hindered by it, while still retaining the ability to use one and mimic IPv4 security behavior. With IPv4, unless you are wealthy enough to afford a static IP for everything in your house, you don't even have the option of exposing more than one device (per port) to the public Internet.
To me, this demonstrates that there's really no downside (besides the obvious implementation cost) to IPv6. People who just want nothing to change, can basically have nothing change. Their IPv6+Firewall network will behave just like an IPv4 one, but people who want to use the capabilities of IPv6 (for example, VoIP using SIP) will be able to, by reconfiguring their firewalls to be a bit smarter about incoming traffic.
"Ladies and gentlemen, my killbot features Lotus Notes and a machine gun. It is the finest available."
Just for fun, try running SIP or H323 through a stateless firewall sometime. Since you're advocating stateless firewalls, I can tell you've never tried....it doesn't work.
SIP, H323, and a bunch of other protocols that are starting to be used regularly as business needs, dynamically allocate ports. You won't know what ports you'll need to allow through the firewall, since they'll be different for every connection. The only way this works is if your stateful firewall understands enough of the protocol to learn which ports it's expecting to see a response on. (In the case of H323, the response may even come from a totally different IP.)
This is precisely the problem that will continue to be the case in IPv6.
``Running out of IP numbers'' is like ``running out of oil'': it'll happen, but crying wolf didn't help the cause. It's claimed IPv6 is Big In Japan but, like popular beat combos, that means ``dead elsewhere''. And I"m sit in a hotel room in Tokyo happily IPv6-free, and i've just come from a building owned by one of the largest IT companies in Japan which was entirely IPv4.
IPv6 has been ``next year'' for the last ten years. It's still no-where. What'sdriving it now that wasn't driving it five years ago?
ian
Software firewalls are a non-sequitor in my opinion. It's really an added layer of obscurity.
If someone installs a firewall and say "please block port 123" I can't help but ask "Why did you open port 123 in the first place, then build a wall in front of it?" The fact that these firewalls exist just shows how stupidly the operating-systems UI is that it is so complicated to determine what apps are listening on the network, and what apps aren't.
Blocking outgoing apps is a completely different issue, and software firewall might make sense for that, if you don't trust the applications on your machine (which is a sad state of affairs anyway)
A protocol that requires a firewall to be stateful just to allow it to pass, I would call broken. And yes, I have for years called FTP a broken protocol (acknowledging that this observation is hindsight). I'm not talking about statefulness for NAT purposes, but rather, statefulness to track permissions on related communications (e.g. the DATA connection in FTP). FTP was designed in the day when no one expected blocking of arbitrary ports. But this is something we will be doing apparently forever.
Let's fix the broken protocols and move forward. While we can use HTTP for many file transfer needs, a new protocol that conducts everything over a single TCP connection or a single SCTP session is where we need to go. Then a firewall can be simple in operation and probably more secure as a result.
now we need to go OSS in diesel cars
Sorry to rain on that parrade, but the (variants of) "IPv6 is secure because it's a 64 bit space and noone will ever guess your address" sound... surrealistic. It's security by obscurity of the worst kind. The kind that can't possibly work.
We live in an age where far larger combinations of bits -- e.g., email addresses or name/password combinations -- are sniffed, phished, compiled into lists and sold, etc. What on Earth makes people think that a fixed IPv6 address would be more secure? No, honestly, what's so special about an 8 byte IPv6 address that makes it un-sniffable?
The notion that your machine is only findable by raw brute-force scanning is pretty laughable. Yes, it's one of the easiest and most non-brainer methods, but it's not the only one.
As a counter-example, look at how email viruses work. Because they _do_ work without scanning and without looking for you speciffically. They just go through more hops, each hop sending itself further to everyone in your address book.
Guess what? The exact same can be trivially adapted to an IPv6 worm. Each pwned machine just continuously looks for incoming and outgoing connections, and tries to spread to those too.
Or how about lists of static addresses, the same as the lists of email addresses that spammers buy and sell. Only unlike email addresses, if you're unfirewalled, you can't keep yours secret. You _have_ to tell each visited site your address every time you connect to it, so it knows where to send the response packets.
So basically it's the setup for the easiest kind of phishing imaginable. It's like automatically giving your email address to every site you ever visited, except this time it's your IPv6 address. Someone just has to create or pwn a popular site, and just record all the IP's that connect to it. Voila, that's a nice list to sell to the hackers. No more brute force scanning needed.
We already have major corporations whose computers are spam bots. What makes you think none will host IP recording bots? How do you know none of the ecommerce sites or forums you visit could be pwned to record all those static IPv6 addresses?
Or it just takes one bored intern working at a major ISP to run a sniffer and get a huge list of all static IPv6 addresses that sent or received anything through their pipe. Remember, idiots exist everywhere. One guy sold the whole list of AOL addresses to spammers, for example. So are you _sure_ noone will sell the list of allocated/known IPv6 addresses?
And since it's static addresses (after all, the whole idea is to get rid of NAT, right? No more dynamic addresses and remapping, right?), you know that each address logged will be available for a long long time thereafter.
Basically let's stop using the whole "we're secure by obscurity" concept to rest already. If there are other security mechanisms in place, fine, I want to hear about them. But "noone will find your IPv6 address" is _not_ security. If you want to talk security, you start from the most paranoid scenarios imaginable, not from wishful thinking.
A polar bear is a cartesian bear after a coordinate transform.
NATing firewalls serve two security purposes and several non security purposes.
The non-security purposes are to multiplex routable IPs so that we don't have to have a public address for each network capable device. That's critical in IPv4, but irrelevant for IPv6 in the forseable future.
The other is so that we can arbitrarily assign IPs to LAN devices (often with DHCP) and be happy. Auto-configuration in IPv6 renders that irrelevant as well.
Now to the security purposes. First and foremost, they provide a default condition where incoming connections are summarily blocked while outgoing are permitted (after NATing). UDP is often configured similarly so that an outbound UDP packet opens a hole for replys to come in through (also after NATing). There is absolutely nothing in IPv6 to prevent the same rules from being configured minus NAT. As a side benefit, without UDP NAT randomizing the port number, two machines behind different firewalls may request a hole by sending UDP packets out iff the firewall is configured to permit it.
The second purpose is to obscure the structure of the LAN behind the firewall including the number of machines on the LAN. It is notable that with IPv6 autoconfig it is entirely possible to find out how many devices are behind the firewall and who made the network devices.
The real question is how valuable is obscuring the addresses of the machines on the LAN and how strongly does NAT guard against leaking that information.
My guess is that NAT doesn't really do a lot there. If the firewall is well configured, most attacks behind it will be the result of users getting viruses and trojans from email and web browsing. A well crafted trojan can easily phone home using an outbound (permitted by NAT) connection and tell the attacker all about what's behind the firewall anyway. The trojan can then act as a socks proxy and allow the attacker to effectively have a machine inside the firewall anyway.
In short, there's no reason for NAT at all in IPv6. Any real security benefits to NAT are side effects of it's primary purpose and easily enough implemented properly as security rules to provide security. Network security SHOULD be a process of adding deliberate and considered rules to a firewall. It should NOT be an ill-considered side effect of solving an entirely different class of problem.
The real question is how much do those firewall rules spoil the idea of everything having a routable address. My opinion is not all that much. A firewall is simply a sort of rules server device that offloads filtering (ideally as a first line of defense backed up on the machine being protected) and centralizes policy, even in the face of mis-configured machines. Those rules would (hopefully) still be there without the firewall (who wants random people sshing or VNCing to their desktop machine), so the effect is more or less nil as far as routability goes. After all, even servers running without a firewall are often configured with hosts.(allow|deny).