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End Of the Line for SpeakFreely: NATed to Death
Arun writes "John Walker (of AutoDesk and Fourmilab fame), primary author of SpeakFreely, has decided to EOL the program (a pioneering network telephony effort), come January 15th, 2004. He cites difficulty in maintaining a decade-old code base, lack of appropriate developer support and a fundamental change in the peer-to-peer nature of the Internet upon which SF is dependent as motivating factors behind his decision. While the last release of the program will continue to be available from SourceForge, the main web site, mailing list, and web forum will be shut down on the aforementioned date." He's got some good points too, like how once IPv6 is more common, most users probably won't go back to one address per machine. I know I enjoy the added security of a NATed firewall, and without a really good reason, I won't be quick to give it up.
Why did I discover this cool application in a discontinuation announcement?
I wish I had discovered it earlier.
Oh well, I can only hope that I can repent this mistake in my next life.
NAT is about address use, not security. In no way should NAT ever be confused with security, even if it appears to give you some security.
Every single security feature you like about NAT can also be had without NAT.
The common things people think they get with nat:
- Connections that must initiate from inside the network.
This is easily achieved with a normal firewall and routable addresses as well.
- My addresses aren't routable, so I'm more secure.
No, your addresses are perfectly routable, just the internet at large does not route them by agreement. Your ISP could easily configure it's routers to get traffic in to your network on those addresses.
- It hides the real addresses of my machines.
Not really... or more accurately, to an outside attacker, those addresses dont mean anyhting anyway. Whether they are known or not is not relevant. A firewall in front of a network of routable addresses could hide things equally well.
NAT by itslef does not reduce exposure. The best example of this would be those who configure nat in a hurry on linux 2.4 systems..... they set up an SNAT or masquerade rule in postrouting, and that's it.
That's nat, full, 100% working nat.
With absolutely no security.
The ISP could route to their internal network, no problem, making connections to whatever they want.
This is easily fixed by a few rules.. but then you are into firewalling, and not NAT at all.
Walker also lists an entire slew of other reasons, but if he used the NAT argument as his central reason to quit, I think he's being very short-sighted. Of course, "because I don't wanna" is always a perfectly valid reason in an open source world, too.
You can have a good and secure firewall even without NAT, in case you didn't know..
Ahh, but NAT is the simplest. I like the fact that I can get a hardware NATting firewall, plug it in, and know that the default configuration is secure. There aren't any holes anywhere, no cracker is gonna scan my network through it, nothing like that...
Sure you can get that with a regular firewall, but you have to configure it and monitor it and all sorts of other stuff that I, as a consumer, just don't want to do.
And FYI, I work in the TCP/IP security business. It's not that I don't know how to build a firewall. It's that I don't WANT to when I'm off work...
I am disrespectful to dirt! Can you see that I am serious?!
First off, let me say I have no idea what Speak Freely is. My comments are solely in response to some of the reasons he gives for discontinuing the program.
Had his reasoning behind discontinuing the project rested solely on his lack of time and an aging code base, I don't think I'd have an issue. Instead, he goes on to blame the NAT protocol and boxes that implement it, like the very popular cable/DSL "routers," and many of his issues seem to either misunderstand them or deliberately misstate what they can do.
He makes comments like, "Since the user no longer has an externally visible Internet Protocol (IP) address (fixed or variable), there is no way (in the general case--there may be "workarounds" for specific NAT boxes, but they're basically exploiting bugs which will probably eventually be fixed) for sites to open connections or address packets to his machine." He continues to state, "experience has shown that a large number of installed NAT boxes either cannot map an externally accessible port to an internal IP address and port, or those who install the boxes do not provide their customers adequate information to permit them to do this."
First of all, I have yet to see a NAT device that cannot statically map ports to a machine inside the local area connection. If there is one, I'd love to know about it so I can tell anyone to avoid it. Some are more rudimentary than others - like one I know about that has no UI to distinguish TCP and UDP inbound ports - but they all offer some way of mapping inbound ports.
His argument that they don't provide sufficient documentation to allow end-users to do so, and this may be the case. But if one is to discontinue development of a program based on the fact that someone else is providing poor documentation, there wouldn't be any development going on - documentation for most hardware/software products in the last 3 years or more have been horrid in my experience.
His argument that the internet is moving towards a client-server model rather than a peer to peer model is undeniable. It's been moving that way since they allowed home computers on the internet, and shouldn't be a surprise to anyone. Still, this doesn't mean the "clients" can't continue to utilize products that utilize a peer to peer architecture. He dismisses peer to peer file sharing products while overlooking the fact that they're the most successful peer to peer architecture network to exist in the history of the internet, and disproves his argument that NAT spells the end of peer to peer.
In the end, it seems he just didn't want to continue developing his program - and instead of being honest, he thought he'd use this opportunity to climb on his soapbox and make some waves by blaming NAT for the ills of the internet and the death of his program.
It is not a matter of (just) static port mapping, it is more a fundamental problem in the way DNS works with Internet addressing -- or more specifically, the way way applications interact with Internet addressing. (This will no doubt invite flames from those outraged at the idea that there might be a fundamental problem/mistake in the Internet.)
More specifically, what happens when you have multiple machines behind the NAT device? How do you map the ports statically to multiple machines *and* also communicate this information to devices on the outside of the NAT device? (That is, port 80 on the NAT device maps to server1, port 81 on the NAT device maps to server2, etc.)
The key issue is that applications are using network level addressing (IP addresses) rather than application level addresses (URLs) to establish the network connection -- we have network specific information far too embedded in the applications, which is why the transition from IPv4 to IPv6 is such a nuisance. At the moment, the DNS SRV record could help with some of these matters by specifying a port number to use for a specific service and host/domain.
A better design for applications would be for them to be completely unaware of 'IP addresses' and function purely on URLs or hostnames + service name, and link to libraries or network drivers on the machine that handle the network aspects. Really -- excepting network mangement tools, what application bothers about the MAC addresses of machines or PPP negotiation details? IP addresses should not matter to the applications, either -- at that point, much of the arguments against NAT go away.
Honestly, the fact that NAT causes applications to break is more a reflection on mistakes in the architecture/application. IP packets themselves don't fall over and die just because they transition from a PPP link to wireless to ethernet to SONET to etc. The differing layers are independent of one another -- the applications have not yet been weaned off directly diddling with the IP layer.