On Tue, 23 Oct 2001 11:38:36 EDT, jkruser said: > problem is...looks like, to me, that it is not coming from outside...thus > the ingress filtering will not stop it. Or am I missing something? > 79, 2001-10-23 02:57:31, 2000205, Possible Fraggle attack initiated, > MY.C.BLOCK.177, , 0.0.0.0, , dstport=7&srcport=21497, 1 The trick here is to remember that ingress filtering will *not* stop these packets (as you noted, they originate inside the filter). What you need to do is find the packet that's being sent IN that's causing these replies, and ingress filter THAT. This is similar to stopping SMURF attacks (which consist of streams of ICMP Echo Reply packets) by configuring your routers to Do The Right Thing(*) with ICMP Echo *Request* packets.... -- Valdis Kletnieks Operating Systems Analyst Virginia Tech (*) The Right Thing is documented in RFC2644 "Changing the Default for Directed Broadcast in Routers". To summarize - routers should drop packets going to a subnet's broadcast address by default, and it should only be enabled if you know what you're doing....
This archive was generated by hypermail 2b30 : Tue Oct 23 2001 - 10:09:51 PDT