Date: Mon, 19 May 2025 08:20:18 +0000 From: bugzilla-noreply@freebsd.org To: net@FreeBSD.org Subject: [Bug 254675] ICMP Unreach needfrag is broken in 13.0-RC4 Message-ID: <bug-254675-7501-arxA4zC4yr@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-254675-7501@https.bugs.freebsd.org/bugzilla/> References: <bug-254675-7501@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=254675 mjl@luckie.org.nz changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |mjl@luckie.org.nz --- Comment #5 from mjl@luckie.org.nz --- Yes. I'm on 14.2 and I too see the frag needed on loopback in IPv4, but only as of today. It hadn't occurred to me that that is where the PTBs were, so I've only looked to see that's where they are. The same system generates packet too big messages correctly in IPv6 (without the presence of NAT). $ sudo tcpdump -n -v -i lo0 Password: tcpdump: listening on lo0, link-type NULL (BSD loopback), snapshot length 262144 bytes 20:11:51.330869 IP (tos 0x0, ttl 64, id 59115, offset 0, flags [none], proto ICMP (1), length 596, bad cksum 0 (->7048)!) 127.0.0.1 > 118.92.XXX.XXX: ICMP 192.172.226.122 unreachable - need to frag (mtu 1492), length 576 IP (tos 0x0, ttl 254, id 18, offset 0, flags [DF], proto UDP (17), length 1500) 118.92.XXX.XXX.65426 > 192.172.226.122.33435: UDP, length 1472 Setup is: em0: flags=1008943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST,LOWER_UP> metric 0 mtu 1500 inet 192.168.3.1 netmask 0xffffff00 broadcast 192.168.3.255 tun0: flags=1008051<UP,POINTOPOINT,RUNNING,MULTICAST,LOWER_UP> metric 0 mtu 1492 options=80000<LINKSTATE> inet 118.92.XXX.XXX --> 118.92.XXX.XXX netmask 0xffffff00 ipfw, with kernel nat. Note that the packet too big message should be sent on em0, with a source address of 192.168.3.1, to 192.168.3.XXX. Instead, its being generated on loopback, and with a destination address derived from tun0. -- You are receiving this mail because: You are on the CC list for the bug. You are the assignee for the bug.help
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