"Forrest W. Christian" writes:
Maybe I'm missing something here, but wouldn't these Denial of Service attacks cause a severe mismatch in the numbers of SYNs and SYN-ACKs on a given router interface? [...] Then, if the ratio got too high, it can start yelping about "Potential SYN D-O-S Atttack in progress on Interface Serial 1"
In this manner "good" isp's wouldn't unknowingly carry these attacks.
I think it is easier to just block the attacks completely by source filtering your own network, at which point you can't carry such an attack, knowingly or unknowingly.
I envision this being done on the somewhat bigger isp's where putting inbound filters on their customer interfaces would be not a good idea (Sprint, MCI, Net 99, etc.).
What you propose is actually much harder to build than filters are.
Personally, I know that these attacks aren't going to originate at our site, as I have the filters on. However, I am quite concerned about getting hit with one...
Please help, then, in convincing people that it is important to turn on filtering on all leaf networks. Perry