Syn flooding attacks

Peter Evans peter at
Mon Oct 20 23:18:14 UTC 1997

Phil Howard <phil at> wrote: 

	[about SYN flooding]

|I don't know of any routers that have these or other means of dealing with
|the SYN attacks.

	If you search cco for "tcp intercept", you should find
	something interesting. This feature was available in
	11.2(4)F.  ((paraphrased from memory))

	Basically the router completed the handshaking then passed
	on the completed connection to the inside host.

	When under attack, it halves the timeouts (progressively?)
	for half-open connections.

	I don't know what happened to the F branch. It seems to have
	been left behind.


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The Random Road, they keep the peace, they eat donuts.    -TRR '97

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