NAT Breaks the Net


Most broadband connections, such as the cable modem in my apartment and whatever drives the wireless network here, are assigned a single network address, and NAT (network address translation) is used to share that one address among all the devices on the network. The broadband gateway devices that do this are readily available and inexpensive.

There is a small problem with this arrangement: the Internet was not designed to work this way. Every device on the network is supposed to get its own unique address. When addresses are shared, stuff breaks. For instance, right now I'd like to copy a file from the server in my apartment to the hard disk of my laptop. I can't do that, because the NATs on both sides prevent me from setting up a direct point-to-point connection.

There are workarounds. I could copy the file from the server to the gateway on my network, and from there to the laptop. Or, I could setup a proxy on the gateway that forwards connections to the server. There are things I could do, but that doesn't change the fact that the Internet isn't working for me the way it should. NAT broke the network.

Most people don't experience the sorts of problems I'm having. If you just read mail or browse web pages, the NAT won't get in your way. Problems arise with less common services and situations--but they are starting to become more common. When a small business moves its network behind a NAT on a broadband connection, travellers may lose remote access the network. The equipment manufacturers portray this is a benefit: "It's a firewall to isolate your servers from the net." I wonder if people are going to start realizing NAT really is a bug, not a feature.


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re: NAT Breaks the Net

Do you still have that Dell Laserlink bought you? I remember when you came out to Philly one time, and you were just tickled pink that you were 35,000 feet in the air, in First Class, compiling sendmail on your Dell laptop running Linux. Of all the crappy things that happened at LL, I remember that as one of the good memories from that ordeal.

re: NAT Breaks the Net

NAT doesn't break the net anymore than a firewall breaks the net, or dhcp breaks the net (what, no fixed IP? you broke the net!) or classless routing breaks the net (what, network allocations not on byte boundaries? you broke the net!). Heck, if you want to put your server on the net without it being NAT'd, you're free to do so... at the cost of having to pay for another IP address for the rest of your machines. Arguably NAT *saved* the net from running out of IP addresses.