DoS, ICMP, proxies, SYNDefender

Tim Bass bass at linux.silkroad.com
Thu Oct 3 21:58:28 UTC 1996


>    Tim, unfortunately ICMP UNREACHABLE can be sent some intermediate
> router during routing flip process. For this reason some customer
> prefer cut off this sort of ICMP - it would break running TCP connection.

Understood, however the conditions to terminate the connection
is not just as simple as UNREACHABLE.  A few possible conditions:

(1) UNREACHABLE && TCP_SYN_STATE


(2) UNREACHABLE && TCP_SYN_STATE && sk->time_in_state


VR,

Tim







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