Date: Sat, 31 Aug 2002 02:50:09 -0700 (PDT) From: Martin.Kaeske@Stud.TU-Ilmenau.DE To: freebsd-bugs@FreeBSD.org Subject: Re: kern/42137: Path MTU broken - initial too-large pa Message-ID: <200208310950.g7V9o9l1066255@freefall.freebsd.org>
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The following reply was made to PR kern/42137; it has been noted by GNATS. From: Martin.Kaeske@Stud.TU-Ilmenau.DE To: freebsd-gnats-submit@FreeBSD.org, jeff@expertcity.com Cc: Subject: Re: kern/42137: Path MTU broken - initial too-large pa Date: 31 Aug 2002 09:46:44 -0000 Hello, I have an OpenBSD-2.9 machine (with ipfilter-3.4.16) acting as a router for my LAN and i have similar problems (MTU is lowered but FBSD keeps sending too large packets). I found out that it's not FreeBSDs fault it's the router sending wrong ICMP messages. The ICMP message should contain the IP-header and the first 8 bytes of data from the IP-packet that caused the error but OpenBSD doesn't include the 8 bytes. Since FreeBSD seems to need src/dst ip-address _and_ port number to react properly to the ICMP message and since src/dst port number are located in this 8 bytes FBSD keeps sending to large packets. Once i disabled ipfilter in OpenBSD (build a kernel without 'options IPFILTER') the problem disappeared (that means the ICMP messages are correct). Can you check if you're also getting such wrong ICMP-messages? Martin To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message
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