Can You Spoof IP Packets?

nweaver writes "Spoofed IP packets are still believed to be a significant problem for the Internet. But are they? The Spoofer Project is attempting to measure the problem. Apparently, 80% of the IP addresses measured no longer support spoofing! Their methodology is simple: have users download a client which attempts to spoof packets to the monitor. Using these packets, they can determine the filter rules. So everyone, download the client and help!"

Comments

Re:I think I speak for most of us when I say...

[squiggleslash]

I'm having difficulty figuring it out too.

IP spoofing isn't even a bad thing. There's a work-around that allows two hosts hidden behind NAT gateways to communicate directly with one another by having them both spoof a cooperating proxy. (It goes something like: Host A establishes a UDP link with the proxy, Host B establishes a UDP link with a proxy, Proxy then gives A enough information to allow it to spoof packets as Proxy and send them directly to B, and proxy gives B the information needed to spoof packets from Proxy to A.)

This is useful in some P2P applications, notably VoIP.

This is going to break if spoofing some how gets prevented completely, and from what I can figure out, that's what the above system is treating as some kind of "hole" that needs to be fixed.