kern/115413: [ipv6] ipv6 pmtu not working

Tue Aug 21 06:38:05 PDT 2007

On Tue, 2007-08-21 at 14:11 +0200, Daniel Hartmeier wrote:
> But th_seq of the TCP packet quoted by the ICMPv6 error is 2463010534,
> which is outside dst's window. Strangely, it is within src's window.
> 
> I don't understand why some_router would do this. It looks like it's
> either quoting the wrong TCP header or sending the error to the wrong
> side, neither of which sounds like an easy mistake to make.
> Is some_router a FreeBSD 6.2 box, too?

It is Cisco 7200. Btw, these icmp packets are accepted by FreeBSD kernel
after disabling pf.
> 
> It might help if you could capture a tcpdump -s 1600 -nvvvS of one
> such
> TCP connection, including the ICMPv6 error.

Attached.

	Jacek
-------------- next part --------------
15:08:36.600927 IP6 (flowlabel 0x2d89b, hlim 64, next-header: TCP (6), length: 44) src_addr.55687 > 2002:594c:de3e:1::4.22: S, cksum 0x3013 (correct), 2820359509:2820359509(0) win 65535 <mss 1440,nop,wscale 1,nop,nop,timestamp 1049216467 0,sackOK,eol>
15:08:36.847498 IP6 (hlim 51, next-header: TCP (6), length: 40) 2002:594c:de3e:1::4.22 > src_addr.55687: S, cksum 0x760f (correct), 1624375639:1624375639(0) ack 2820359510 win 5712 <mss 1440,sackOK,timestamp 348791 1049216467,nop,wscale 3>
15:08:36.847545 IP6 (flowlabel 0x2d89b, hlim 64, next-header: TCP (6), length: 32) src_addr.55687 > 2002:594c:de3e:1::4.22: ., cksum 0x39d6 (correct), 2820359510:2820359510(0) ack 1624375640 win 32844 <nop,nop,timestamp 1049216708 348791>
15:08:37.175719 IP6 (hlim 51, next-header: TCP (6), length: 63) 2002:594c:de3e:1::4.22 > src_addr.55687: P, cksum 0x8f50 (correct), 1624375640:1624375671(31) ack 2820359510 win 714 <nop,nop,timestamp 348854 1049216708>
15:08:37.228281 IP6 (flowlabel 0x2d89b, hlim 64, next-header: TCP (6), length: 71) src_addr.55687 > 2002:594c:de3e:1::4.22: P, cksum 0x4e20 (correct), 2820359510:2820359549(39) ack 1624375671 win 32844 <nop,nop,timestamp 1049216929 348854>
15:08:37.479614 IP6 (hlim 51, next-header: TCP (6), length: 32) 2002:594c:de3e:1::4.22 > src_addr.55687: ., cksum 0xb598 (correct), 1624375671:1624375671(0) ack 2820359549 win 714 <nop,nop,timestamp 348948 1049216929>
15:08:37.479661 IP6 (flowlabel 0x2d89b, hlim 64, next-header: TCP (6), length: 784) src_addr.55687 > 2002:594c:de3e:1::4.22: P, cksum 0x044c (correct), 2820359549:2820360301(752) ack 1624375671 win 32844 <nop,nop,timestamp 1049217174 348948>
15:08:37.491658 IP6 (hlim 51, next-header: TCP (6), length: 736) 2002:594c:de3e:1::4.22 > src_addr.55687: P, cksum 0x1d04 (correct), 1624375671:1624376375(704) ack 2820359549 win 714 <nop,nop,timestamp 348948 1049216929>
15:08:37.594223 IP6 (flowlabel 0x2d89b, hlim 64, next-header: TCP (6), length: 56) src_addr.55687 > 2002:594c:de3e:1::4.22: P, cksum 0x02ab (correct), 2820360301:2820360325(24) ack 1624376375 win 32844 <nop,nop,timestamp 1049217286 348948>
15:08:37.764034 IP6 (hlim 51, next-header: TCP (6), length: 32) 2002:594c:de3e:1::4.22 > src_addr.55687: ., cksum 0xadef (correct), 1624376375:1624376375(0) ack 2820360301 win 902 <nop,nop,timestamp 349020 1049217174>
15:08:37.842637 IP6 (hlim 51, next-header: TCP (6), length: 32) 2002:594c:de3e:1::4.22 > src_addr.55687: ., cksum 0xad54 (correct), 1624376375:1624376375(0) ack 2820360325 win 902 <nop,nop,timestamp 349039 1049217286>
15:08:37.843493 IP6 (hlim 51, next-header: TCP (6), length: 184) 2002:594c:de3e:1::4.22 > src_addr.55687: P, cksum 0xd122 (correct), 1624376375:1624376527(152) ack 2820360325 win 902 <nop,nop,timestamp 349040 1049217286>
15:08:37.845620 IP6 (flowlabel 0x2d89b, hlim 64, next-header: TCP (6), length: 176) src_addr.55687 > 2002:594c:de3e:1::4.22: P, cksum 0x47e6 (correct), 2820360325:2820360469(144) ack 1624376527 win 32844 <nop,nop,timestamp 1049217531 349040>
15:08:38.112932 IP6 (hlim 51, next-header: TCP (6), length: 688) 2002:594c:de3e:1::4.22 > src_addr.55687: P, cksum 0x2a74 (correct), 1624376527:1624377183(656) ack 2820360469 win 1090 <nop,nop,timestamp 349103 1049217531>
15:08:38.369997 IP6 (flowlabel 0x2d89b, hlim 64, next-header: TCP (6), length: 32) src_addr.55687 > 2002:594c:de3e:1::4.22: ., cksum 0x2a41 (correct), 2820360469:2820360469(0) ack 1624377183 win 32844 <nop,nop,timestamp 1049217883 349103>
15:08:40.948002 IP6 (flowlabel 0x2d89b, hlim 64, next-header: TCP (6), length: 48) src_addr.55687 > 2002:594c:de3e:1::4.22: P, cksum 0x1892 (correct), 2820360469:2820360485(16) ack 1624377183 win 32844 <nop,nop,timestamp 1049219793 349103>
15:08:41.295621 IP6 (hlim 51, next-header: TCP (6), length: 32) 2002:594c:de3e:1::4.22 > src_addr.55687: ., cksum 0x9bb5 (correct), 1624377183:1624377183(0) ack 2820360485 win 1090 <nop,nop,timestamp 349887 1049219793>
15:08:41.295666 IP6 (flowlabel 0x2d89b, hlim 64, next-header: TCP (6), length: 80) src_addr.55687 > 2002:594c:de3e:1::4.22: P, cksum 0x6fad (correct), 2820360485:2820360533(48) ack 1624377183 win 32844 <nop,nop,timestamp 1049220132 349887>
15:08:41.541047 IP6 (hlim 51, next-header: TCP (6), length: 32) 2002:594c:de3e:1::4.22 > src_addr.55687: ., cksum 0x99e5 (correct), 1624377183:1624377183(0) ack 2820360533 win 1090 <nop,nop,timestamp 349964 1049220132>
15:08:41.542040 IP6 (hlim 51, next-header: TCP (6), length: 80) 2002:594c:de3e:1::4.22 > src_addr.55687: P, cksum 0x3c86 (correct), 1624377183:1624377231(48) ack 2820360533 win 1090 <nop,nop,timestamp 349964 1049220132>
15:08:41.542181 IP6 (flowlabel 0x2d89b, hlim 64, next-header: TCP (6), length: 96) src_addr.55687 > 2002:594c:de3e:1::4.22: P, cksum 0xa389 (correct), 2820360533:2820360597(64) ack 1624377231 win 32844 <nop,nop,timestamp 1049220372 349964>
15:08:41.822764 IP6 (hlim 51, next-header: TCP (6), length: 96) 2002:594c:de3e:1::4.22 > src_addr.55687: P, cksum 0xa6ad (correct), 1624377231:1624377295(64) ack 2820360597 win 1090 <nop,nop,timestamp 350027 1049220372>
15:08:41.974328 IP6 (flowlabel 0x2d89b, hlim 64, next-header: TCP (6), length: 32) src_addr.55687 > 2002:594c:de3e:1::4.22: ., cksum 0x1aee (correct), 2820360597:2820360597(0) ack 1624377295 win 32844 <nop,nop,timestamp 1049220642 350027>
15:08:44.045893 IP6 (flowlabel 0x2d89b, hlim 64, next-header: TCP (6), length: 176) src_addr.55687 > 2002:594c:de3e:1::4.22: P, cksum 0xf110 (correct), 2820360597:2820360741(144) ack 1624377295 win 32844 <nop,nop,timestamp 1049222367 350027>
15:08:44.295775 IP6 (hlim 51, next-header: TCP (6), length: 64) 2002:594c:de3e:1::4.22 > src_addr.55687: P, cksum 0x9b15 (correct), 1624377295:1624377327(32) ack 2820360741 win 1278 <nop,nop,timestamp 350652 1049222367>
15:08:44.295998 IP6 (flowlabel 0x2d89b, hlim 64, next-header: TCP (6), length: 96) src_addr.55687 > 2002:594c:de3e:1::4.22: P, cksum 0x4f17 (correct), 2820360741:2820360805(64) ack 1624377327 win 32844 <nop,nop,timestamp 1049222612 350652>
15:08:44.544649 IP6 (hlim 51, next-header: TCP (6), length: 80) 2002:594c:de3e:1::4.22 > src_addr.55687: P, cksum 0xc614 (correct), 1624377327:1624377375(48) ack 2820360805 win 1278 <nop,nop,timestamp 350714 1049222612>
15:08:44.544834 IP6 (flowlabel 0x2d89b, hlim 64, next-header: TCP (6), length: 96) src_addr.55687 > 2002:594c:de3e:1::4.22: P, cksum 0xa2c9 (correct), 2820360805:2820360869(64) ack 1624377375 win 32844 <nop,nop,timestamp 1049222854 350714>
15:08:44.801386 IP6 (hlim 51, next-header: TCP (6), length: 80) 2002:594c:de3e:1::4.22 > src_addr.55687: P, cksum 0xd629 (correct), 1624377375:1624377423(48) ack 2820360869 win 1278 <nop,nop,timestamp 350778 1049222854>
15:08:44.903997 IP6 (flowlabel 0x2d89b, hlim 64, next-header: TCP (6), length: 32) src_addr.55687 > 2002:594c:de3e:1::4.22: ., cksum 0x0c6c (correct), 2820360869:2820360869(0) ack 1624377423 win 32844 <nop,nop,timestamp 1049223205 350778>
15:08:45.147735 IP6 (hlim 51, next-header: TCP (6), length: 80) 2002:594c:de3e:1::4.22 > src_addr.55687: P, cksum 0xe6af (correct), 1624377423:1624377471(48) ack 2820360869 win 1278 <nop,nop,timestamp 350866 1049223205>
15:08:45.148027 IP6 (flowlabel 0x2d89b, hlim 64, next-header: TCP (6), length: 96) src_addr.55687 > 2002:594c:de3e:1::4.22: P, cksum 0xb0b8 (correct), 2820360869:2820360933(64) ack 1624377471 win 32844 <nop,nop,timestamp 1049223442 350866>
15:08:45.391362 IP6 (flowlabel 0xae0ac, hlim 64, next-header: TCP (6), length: 1460) src_addr.53916 > dst_addr.22: ., cksum 0x351e (correct), 1982161698:1982163126(1428) ack 1447942263 win 32844 <nop,nop,timestamp 1049223680 309846>
15:08:45.394947 IP6 (hlim 63, next-header: ICMPv6 (58), length: 1240) some_router > src_addr: [icmp6 sum ok] ICMP6, packet too big, length 1240, mtu 1480
15:08:45.399300 IP6 (hlim 51, next-header: TCP (6), length: 80) 2002:594c:de3e:1::4.22 > src_addr.55687: P, cksum 0x86c9 (correct), 1624377471:1624377519(48) ack 2820360933 win 1278 <nop,nop,timestamp 350927 1049223442>
15:08:45.724239 IP6 (flowlabel 0x2d89b, hlim 64, next-header: TCP (6), length: 1460) src_addr.55687 > 2002:594c:de3e:1::4.22: ., cksum 0x4707 (correct), 2820360933:2820362361(1428) ack 1624377519 win 32844 <nop,nop,timestamp 1049223854 350927>
15:08:45.724252 IP6 (flowlabel 0x2d89b, hlim 64, next-header: TCP (6), length: 1460) src_addr.55687 > 2002:594c:de3e:1::4.22: ., cksum 0x2e2b (correct), 2820362361:2820363789(1428) ack 1624377519 win 32844 <nop,nop,timestamp 1049223854 350927>
15:08:45.724260 IP6 (flowlabel 0x2d89b, hlim 64, next-header: TCP (6), length: 232) src_addr.55687 > 2002:594c:de3e:1::4.22: P, cksum 0x891c (correct), 2820363789:2820363989(200) ack 1624377519 win 32844 <nop,nop,timestamp 1049223854 350927>
15:08:45.727576 IP6 (hlim 63, next-header: ICMPv6 (58), length: 1240) some_router > src_addr: [icmp6 sum ok] ICMP6, packet too big, length 1240, mtu 1480
15:08:45.728669 IP6 (hlim 63, next-header: ICMPv6 (58), length: 1240) some_router > src_addr: [icmp6 sum ok] ICMP6, packet too big, length 1240, mtu 1480
15:08:45.985316 IP6 (hlim 51, next-header: TCP (6), length: 44) 2002:594c:de3e:1::4.22 > src_addr.55687: ., cksum 0x51d7 (correct), 1624377519:1624377519(0) ack 2820360933 win 1278 <nop,nop,timestamp 351071 1049223442,nop,nop,sack 1 {2820363789:2820363989}>
15:08:46.435406 IP6 (flowlabel 0x2d89b, hlim 64, next-header: TCP (6), length: 1460) src_addr.55687 > 2002:594c:de3e:1::4.22: ., cksum 0x43b1 (correct), 2820360933:2820362361(1428) ack 1624377519 win 32844 <nop,nop,timestamp 1049224564 351071>
15:08:46.438283 IP6 (hlim 63, next-header: ICMPv6 (58), length: 1240) some_router > src_addr: [icmp6 sum ok] ICMP6, packet too big, length 1240, mtu 1480
15:08:47.953287 IP6 (flowlabel 0x2d89b, hlim 64, next-header: TCP (6), length: 1460) src_addr.55687 > 2002:594c:de3e:1::4.22: ., cksum 0x3eed (correct), 2820360933:2820362361(1428) ack 1624377519 win 32844 <nop,nop,timestamp 1049225784 351071>
15:08:47.956548 IP6 (hlim 63, next-header: ICMPv6 (58), length: 1240) some_router > src_addr: [icmp6 sum ok] ICMP6, packet too big, length 1240, mtu 1480
15:08:50.857446 IP6 (flowlabel 0x2d89b, hlim 64, next-header: TCP (6), length: 1460) src_addr.55687 > 2002:594c:de3e:1::4.22: ., cksum 0x3593 (correct), 2820360933:2820362361(1428) ack 1624377519 win 32844 <nop,nop,timestamp 1049228178 351071>
15:08:50.860910 IP6 (hlim 63, next-header: ICMPv6 (58), length: 1240) some_router > src_addr: [icmp6 sum ok] ICMP6, packet too big, length 1240, mtu 1480
15:08:55.479100 IP6 (flowlabel 0x2d89b, hlim 64, next-header: TCP (6), length: 1460) src_addr.55687 > 2002:594c:de3e:1::4.22: ., cksum 0x23d1 (correct), 2820360933:2820362361(1428) ack 1624377519 win 32844 <nop,nop,timestamp 1049232724 351071>
15:08:55.481831 IP6 (hlim 63, next-header: ICMPv6 (58), length: 1240) some_router > src_addr: [icmp6 sum ok] ICMP6, packet too big, length 1240, mtu 1480
-------------- next part --------------
Aug 21 15:06:01 FreeBSD kernel: pf: BAD ICMP 2:0 some_router -> src_addr state: TCP src_addr[53916] src_addr[53916] dst_addr[22] [lo=1982164754 high=1982171922 win=32844 modulator=0 wscale=1] [lo=1447942263 high=1448007951 win=1278 modulator=0 wscale=3] 4:4 seq=1982161698
Aug 21 15:06:01 FreeBSD kernel: pf: BAD ICMP 2:0 some_router -> src_addr state: TCP src_addr[53916] src_addr[53916] dst_addr[22] [lo=1982164754 high=1982171922 win=32844 modulator=0 wscale=1] [lo=1447942263 high=1448007951 win=1278 modulator=0 wscale=3] 4:4 seq=1982163126
Aug 21 15:06:02 FreeBSD kernel: pf: BAD ICMP 2:0 some_router -> src_addr state: TCP src_addr[53916] src_addr[53916] dst_addr[22] [lo=1982164754 high=1982171922 win=32844 modulator=0 wscale=1] [lo=1447942263 high=1448007951 win=1278 modulator=0 wscale=3] 4:4 seq=1982161698
Aug 21 15:06:05 FreeBSD kernel: pf: BAD ICMP 2:0 some_router -> src_addr state: TCP src_addr[53916] src_addr[53916] dst_addr[22] [lo=1982164754 high=1982171922 win=32844 modulator=0 wscale=1] [lo=1447942263 high=1448007951 win=1278 modulator=0 wscale=3] 4:4 seq=1982161698
Aug 21 15:06:10 FreeBSD kernel: pf: BAD ICMP 2:0 some_router -> src_addr state: TCP src_addr[53916] src_addr[53916] dst_addr[22] [lo=1982164754 high=1982171922 win=32844 modulator=0 wscale=1] [lo=1447942263 high=1448007951 win=1278 modulator=0 wscale=3] 4:4 seq=1982161698
Aug 21 15:06:16 FreeBSD kernel: pf: BAD ICMP 2:0 some_router -> src_addr state: TCP src_addr[53248] src_addr[53248] dst_addr[22] [lo=947831351 high=947838471 win=32844 modulator=0 wscale=1] [lo=1374559184 high=1374624872 win=1278 modulator=0 wscale=3] 4:4 seq=947828247
Aug 21 15:06:20 FreeBSD kernel: pf: BAD ICMP 2:0 some_router -> src_addr state: TCP src_addr[53916] src_addr[53916] dst_addr[22] [lo=1982164754 high=1982171922 win=32844 modulator=0 wscale=1] [lo=1447942263 high=1448007951 win=1278 modulator=0 wscale=3] 4:4 seq=1982161698
Aug 21 15:06:36 FreeBSD kernel: pf: BAD ICMP 2:0 some_router -> src_addr state: TCP src_addr[53916] src_addr[53916] dst_addr[22] [lo=1982164754 high=1982171922 win=32844 modulator=0 wscale=1] [lo=1447942263 high=1448007951 win=1278 modulator=0 wscale=3] 4:4 seq=1982161698
Aug 21 15:06:57 FreeBSD kernel: pf: BAD ICMP 2:0 some_router -> src_addr state: TCP src_addr[53916] src_addr[53916] dst_addr[22] [lo=1982164754 high=1982171922 win=32844 modulator=0 wscale=1] [lo=1447942263 high=1448007951 win=1278 modulator=0 wscale=3] 4:4 seq=1982161698
Aug 21 15:08:32 FreeBSD kernel: pf: BAD ICMP 2:0 some_router -> src_addr state: TCP src_addr[53248] src_addr[53248] dst_addr[22] [lo=947831351 high=947838471 win=32844 modulator=0 wscale=1] [lo=1374559184 high=1374624872 win=1278 modulator=0 wscale=3] 4:4 seq=947828247
Aug 21 15:08:45 FreeBSD kernel: pf: BAD ICMP 2:0 some_router -> src_addr state: TCP src_addr[53916] src_addr[53916] dst_addr[22] [lo=1982164754 high=1982171922 win=32844 modulator=0 wscale=1] [lo=1447942263 high=1448007951 win=1278 modulator=0 wscale=3] 4:4 seq=1982161698
Aug 21 15:08:46 FreeBSD kernel: pf: BAD ICMP 2:0 some_router -> src_addr state: TCP src_addr[55687] src_addr[55687] 2002:594c:de3e:1::4[22] [lo=2820363989 high=2820371157 win=32844 modulator=0 wscale=1] [lo=1624377519 high=1624443207 win=1278 modulator=0 wscale=3] 4:4 seq=2820360933
Aug 21 15:08:46 FreeBSD kernel: pf: BAD ICMP 2:0 some_router -> src_addr state: TCP src_addr[55687] src_addr[55687] 2002:594c:de3e:1::4[22] [lo=2820363989 high=2820371157 win=32844 modulator=0 wscale=1] [lo=1624377519 high=1624443207 win=1278 modulator=0 wscale=3] 4:4 seq=2820362361
Aug 21 15:08:46 FreeBSD kernel: pf: BAD ICMP 2:0 some_router -> src_addr state: TCP src_addr[55687] src_addr[55687] 2002:594c:de3e:1::4[22] [lo=2820363989 high=2820371157 win=32844 modulator=0 wscale=1] [lo=1624377519 high=1624443207 win=1278 modulator=0 wscale=3] 4:4 seq=2820360933
Aug 21 15:08:48 FreeBSD kernel: pf: BAD ICMP 2:0 some_router -> src_addr state: TCP src_addr[55687] src_addr[55687] 2002:594c:de3e:1::4[22] [lo=2820363989 high=2820371157 win=32844 modulator=0 wscale=1] [lo=1624377519 high=1624443207 win=1278 modulator=0 wscale=3] 4:4 seq=2820360933
Aug 21 15:08:51 FreeBSD kernel: pf: BAD ICMP 2:0 some_router -> src_addr state: TCP src_addr[55687] src_addr[55687] 2002:594c:de3e:1::4[22] [lo=2820363989 high=2820371157 win=32844 modulator=0 wscale=1] [lo=1624377519 high=1624443207 win=1278 modulator=0 wscale=3] 4:4 seq=2820360933
Aug 21 15:08:55 FreeBSD kernel: pf: BAD ICMP 2:0 some_router -> src_addr state: TCP src_addr[55687] src_addr[55687] 2002:594c:de3e:1::4[22] [lo=2820363989 high=2820371157 win=32844 modulator=0 wscale=1] [lo=1624377519 high=1624443207 win=1278 modulator=0 wscale=3] 4:4 seq=2820360933
Aug 21 15:09:05 FreeBSD kernel: pf: BAD ICMP 2:0 some_router -> src_addr state: TCP src_addr[55687] src_addr[55687] 2002:594c:de3e:1::4[22] [lo=2820363989 high=2820371157 win=32844 modulator=0 wscale=1] [lo=1624377519 high=1624443207 win=1278 modulator=0 wscale=3] 4:4 seq=2820360933