rfc2385 (tcp md5 checksums) in -current broken?

Noritoshi Demizu demizu at dd.iij4u.or.jp
Wed Sep 21 00:11:32 PDT 2005


> > I'm testing rfc2385 support with some of our equipment with current
> > as of a few days ago, and the support seems, well, rather broken.

tcpdump seems to be broken.  I think the patch at the tail of this
e-mail needs to be applied to src/contrib/tcpdump/print-tcp.c.
Could you try this patch?

I think this patch can also be applied to tcpdump 3.9.3.

> I think there is a bug in syncache_respond().

I'm trying to fix this problem.  But,,, I found you don't use SACK in
your trace :-).  Anyway, I will try to fix the bug in syncache_respond().

Regards,
Noritoshi Demizu


--- print-tcp.c-ORG	Thu Apr 21 15:36:05 2005
+++ print-tcp.c	Wed Sep 21 16:07:40 2005
@@ -799,7 +799,7 @@
 	MD5_Update(&ctx, tcpmd5secret, strlen(tcpmd5secret));
 	MD5_Final(sig, &ctx);
 
-	if (memcmp(rcvsig, sig, 16))
+	if (memcmp(rcvsig, sig, 16) == 0)
 		return (SIGNATURE_VALID);
 	else
 		return (SIGNATURE_INVALID);


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