Re: router syn/syn-ack/ack alarming...

["Larry J. Plato" <ljp () ans net>]

> On Wed, 18 Sep 1996, Vern Paxson wrote:
>
> > > have something in their logs like SYN/ACK RATIO 33:1 POSSIBLE HACKER
> > > ATTACK which will make them sit up and take notice.
> >
> > I don't see how in reality to make the syn/syn-ack/ack ratio work soundly.
> > It seems too easy for the cracker to synthesize bogus syn-ack's or ack's to
> > manipulate the ratio however they please.
>
> Wouldn't the ratio be calculated from outgoing SYN's and incoming ACK's?
> I can see that a sophisticated attacker could have a machine on another
> network sending incoming ACK's to balance the outgoing SYN's but I suspect
> this would be an extremely small percentage of attacks.
Until someone implements this as a feature, then 2600 will post the code 
to a program that sends SYNs followed by ACKs a minute later.  The damage
would be done by then, but the stats would show balanced flows.

Larry Plato
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