TCP SYN attacks

Thu Oct 3 21:13:26 UTC 1996

>>>>> The moving finger of Dima Volodin, having written:

    Dima> Any data on how the firewall itself withstands SYN attacks? How much
    Dima> resources are needed to cope with a real attack? From what I've read in
    Dima> their white paper it's just a piece of SYN-processing code that was
    Dima> duplicated (functionally) in the gateway, so all concerns about resource
    Dima> usage and speed seem to be still valid.

    Dima> Dima

I agree.

It seems to me that placing this processing in the firewall is
*potentially* dangerous, as now a SYN-flooding attack (*IF*
*successful*) will deny service to everything behind the firewall,
instead of just the targeted host.

If I know I can fire-hose your firewall, and take your *site* off the
net, then it might become more attractive to me to "find" sufficient
CPU and bandwidth resources to generate enough packets to take you
out.  This could "raise the stakes" enough to make it worth it to an
attacker.

-- 
Tom E. Perrine (tep at SDSC.EDU) | San Diego Supercomputer Center 
http://www.sdsc.edu/~tep/     | Voice: +1.619.534.5000
"Ille Albus Canne Vinco Homines" - You Know Who