Date: Sat, 29 Dec 2001 23:54:35 -0500 (EST) From: Mike Silbersack <silby@silby.com> To: Randall Stewart <randall@stewart.chicago.il.us> Cc: Bosko Milekic <bmilekic@technokratis.com>, <net@FreeBSD.ORG> Subject: Re: m_reclaim and a protocol drain Message-ID: <Pine.BSF.4.30.0112292352490.52452-100000@niwun.pair.com> In-Reply-To: <3C29BEF3.611BCAFE@stewart.chicago.il.us>
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On Wed, 26 Dec 2001, Randall Stewart wrote: > This comment facinates me. The reason we made SACK's in SCTP > revokeable is due to the potential DOS attack that someone > can supposedly lauch if you don't allow the stack to revoke. > > I can actually see the reason that Sally made the comments > and had us change it so that SACK's are revokeable. However > you argue to the contrary and I wonder which is correct. > > If you do not allow revoking it is the same as if a protocol > does not hold a drain() fucntion. A attacker could easily > stuff a lot of out-of-order segments at you and thus > fill up all your mbuf's or clusters (in my current testing > case). This would then yeild a DOS since you could no longer > receive any segments and leave you high and dry.... Heh, you nailed the reverse of the problem we've seen: Right now the easy way to cause exhaustion is to fill up _send_ buffers, via netkill. I guess if we solve that problem, out of order segments could be used for an attack too. Just FWIW, Mike "Silby" Silbersack To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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