Date: Tue, 20 Aug 1996 05:02:43 +1000 (EST) From: michael butler <imb@scgt.oz.au> To: archie@whistle.com (Archie Cobbs) Cc: hackers@freebsd.org Subject: Re: Which fragments to discard (was Re: ipfw vs ipfilter) Message-ID: <199608191902.FAA10601@asstdc.scgt.oz.au> In-Reply-To: <199608190232.TAA26469@bubba.whistle.com> from "Archie Cobbs" at Aug 18, 96 07:32:46 pm
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Archie Cobbs writes: > > Poul-Henning Kamp writes: > > : This is a common mistake, only offset==1 needs to be discarded. > > Hmmm, since there are no comments in ip_fw.c as to why only offset 1 > > is a problem, I'll have to ask here. Why is that? > RFC 1858 supposedly explains why. Speaking of which, what follows slid right past my border router :-( This evening's (-stable + ipfw) log included .. Deny TCP <somehost>:24940 202.14.234.65:26735 Fragment = 34 Deny TCP <somehost>:30569 202.14.234.65:25451 Fragment = 68 Deny TCP <somehost>:31008 202.14.234.65:29807 Fragment = 102 Deny TCP <somehost>:24940 202.14.234.65:26735 Fragment = 34 Deny TCP <somehost>:30569 202.14.234.65:25451 Fragment = 68 Deny TCP <somehost>:31008 202.14.234.65:29807 Fragment = 102 Deny TCP <somehost>:24940 202.14.234.65:26735 Fragment = 34 Deny TCP <somehost>:30569 202.14.234.65:25451 Fragment = 68 Deny TCP <somehost>:31008 202.14.234.65:29807 Fragment = 102 Deny TCP <somehost>:24940 202.14.234.65:26735 Fragment = 34 Deny TCP <somehost>:31008 202.14.234.65:29807 Fragment = 102 Deny TCP <somehost>:30569 202.14.234.65:25451 Fragment = 68 Deny TCP <somehost>:24940 202.14.234.65:26735 Fragment = 34 Deny TCP <somehost>:30569 202.14.234.65:25451 Fragment = 68 Deny TCP <somehost>:31008 202.14.234.65:29807 Fragment = 102 All things considered, I think the decision to configure all my kernels to be "defensive" by default was not such a bad idea. Anyone who can't build packets properly I don't want to talk to and I told them so in email .. michael
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