Path MTU Problem
_lion_2000 at mail.ru
_lion_2000 at mail.ru
Wed Mar 5 20:51:37 PST 2008
Hi, i have a FreeBSD 6.3, fresh install. It is in the corporate network and
i can't use any tcp network service on that machine from any other, which is
behind cisco routers with tunnels.
Well, not all services, but some, when large packets are sent from that box.
After some investigation i found, what router sends ICMP Frag packets to
that box, but it doesn't reduce packets size and keep sending large packets:
trying to 'scp 10.23.0.241:/usr/bin/cc test' from 10.35.1.3
test# tcpdump -s 128 -nvXpi rl0 'icmp or (tcp and host 10.35.1.3)'
tcpdump: listening on rl0, link-type EN10MB (Ethernet), capture size 128
bytes
10:32:01.193385 IP (tos 0x0, ttl 62, id 11830, offset 0, flags [DF], proto:
TCP (6), length: 64) 10.35.1.3.60122 > 10.23.0.241.22: S, cksum 0xa461
(correct), 1652841827:1652841827(0) win 65535 <mss
1380,nop,nop,sackOK,nop,wscale 1,nop,nop,timestamp 48942590 0>
0x0000: 4500 0040 2e36 4000 3e06 f854 0a23 0103 E.. at .6@.>..T.#..
0x0010: 0a17 00f1 eada 0016 6284 5d63 0000 0000 ........b.]c....
0x0020: b002 ffff a461 0000 0204 0564 0101 0402 .....a.....d....
0x0030: 0103 0301 0101 080a 02ea cdfe 0000 0000 ................
10:32:01.193417 IP (tos 0x0, ttl 64, id 1173, offset 0, flags [DF], proto:
TCP (6), length: 64) 10.23.0.241.22 > 10.35.1.3.60122: S, cksum 0xa9cb
(correct), 1543933867:1543933867(0) ack 1652841828 win 65535 <mss
1460,nop,wscale 1,nop,nop,timestamp 38276412 48942590,sackOK,eol>
0x0000: 4500 0040 0495 4000 4006 1ff6 0a17 00f1 E.. at ..@. at .......
0x0010: 0a23 0103 0016 eada 5c06 8fab 6284 5d64 .#......\...b.]d
0x0020: b012 ffff a9cb 0000 0204 05b4 0103 0301 ................
0x0030: 0101 080a 0248 0d3c 02ea cdfe 0402 0000 .....H.<........
10:32:01.226985 IP (tos 0x0, ttl 61, id 11834, offset 0, flags [DF], proto:
TCP (6), length: 52) 10.35.1.3.60122 > 10.23.0.241.22: ., cksum 0x6953
(correct), ack 1 win 32832 <nop,nop,timestamp 48942593 38276412>
0x0000: 4500 0034 2e3a 4000 3d06 f95c 0a23 0103 E..4.:@.=..\.#..
0x0010: 0a17 00f1 eada 0016 6284 5d64 5c06 8fac ........b.]d\...
0x0020: 8010 8040 6953 0000 0101 080a 02ea ce01 ... at iS..........
0x0030: 0248 0d3c .H.<
10:32:01.240159 IP (tos 0x0, ttl 64, id 1174, offset 0, flags [DF], proto:
TCP (6), length: 91) 10.23.0.241.22 > 10.35.1.3.60122: P, cksum 0x7ea9
(correct), 1:40(39) ack 1 win 32832 <nop,nop,timestamp 38276459 48942593>
0x0000: 4500 005b 0496 4000 4006 1fda 0a17 00f1 E..[.. at .@.......
0x0010: 0a23 0103 0016 eada 5c06 8fac 6284 5d64 .#......\...b.]d
0x0020: 8018 8040 7ea9 0000 0101 080a 0248 0d6b ...@~........H.k
0x0030: 02ea ce01 5353 482d 322e 302d 4f70 656e ....SSH-2.0-Open
0x0040: 5353 485f 342e 3570 3120 4672 6565 4253 SSH_4.5p1.FreeBS
0x0050: 442d 3230 3036 3131 3130 0a D-20061110.
10:32:01.272877 IP (tos 0x0, ttl 61, id 11842, offset 0, flags [DF], proto:
TCP (6), length: 93) 10.35.1.3.60122 > 10.23.0.241.22: P, cksum 0x4a45
(correct), 1:42(41) ack 40 win 32832 <nop,nop,timestamp 48942598 38276459>
0x0000: 4500 005d 2e42 4000 3d06 f92b 0a23 0103 E..].B at .=..+.#..
0x0010: 0a17 00f1 eada 0016 6284 5d64 5c06 8fd3 ........b.]d\...
0x0020: 8018 8040 4a45 0000 0101 080a 02ea ce06 ... at JE..........
0x0030: 0248 0d6b 5353 482d 322e 302d 4f70 656e .H.kSSH-2.0-Open
0x0040: 5353 485f 332e 382e 3170 3120 4672 6565 SSH_3.8.1p1.Free
0x0050: 4253 442d 3230 3036 3039 3330 0a BSD-20060930.
10:32:01.274629 IP (tos 0x0, ttl 64, id 1175, offset 0, flags [DF], proto:
TCP (6), length: 788) 10.23.0.241.22 > 10.35.1.3.60122: P 40:776(736) ack 42
win 32832 <nop,nop,timestamp 38276493 48942598>
0x0000: 4500 0314 0497 4000 4006 1d20 0a17 00f1 E..... at .@.......
0x0010: 0a23 0103 0016 eada 5c06 8fd3 6284 5d8d .#......\...b.].
0x0020: 8018 8040 0e95 0000 0101 080a 0248 0d8d ... at .........H..
0x0030: 02ea ce06 0000 02dc 0a14 6169 6371 0c61 ..........aicq.a
0x0040: f50f 7395 7713 6004 dbfe 0000 007e 6469 ..s.w.`......~di
0x0050: 6666 6965 2d68 656c 6c6d 616e 2d67 726f ffie-hellman-gro
0x0060: 7570 2d65 7863 6861 6e67 652d 7368 6132 up-exchange-sha2
0x0070: 3536 56
... ssh negotiation skipped
10:32:04.573132 IP (tos 0x8, ttl 64, id 1207, offset 0, flags [DF], proto:
TCP (6), length: 116) 10.23.0.241.22 > 10.35.1.3.60122: P 2000:2064(64) ack
1618 win 32832 <nop,nop,timestamp 38279773 48942928>
0x0000: 4508 0074 04b7 4000 4006 1f98 0a17 00f1 E..t.. at .@.......
0x0010: 0a23 0103 0016 eada 5c06 977b 6284 63b5 .#......\..{b.c.
0x0020: 8018 8040 25fb 0000 0101 080a 0248 1a5d ...@%........H.]
0x0030: 02ea cf50 2c87 e0f9 2273 b4b0 9484 f73b ...P,..."s.....;
0x0040: 2b6a 55e2 5acc 86c5 dde5 ac66 f45a 4ccf +jU.Z......f.ZL.
0x0050: bad6 fb67 105e c0e7 df4d 2ea9 8db0 38d9 ...g.^...M....8.
0x0060: 8f1a 965f f45a 0a60 e00f f63b cb75 2e9a ..._.Z.`...;.u..
0x0070: 01d4 ..
10:32:04.609779 IP (tos 0x8, ttl 61, id 12019, offset 0, flags [DF], proto:
TCP (6), length: 100) 10.35.1.3.60122 > 10.23.0.241.22: P, cksum 0x413e
(correct), 1618:1666(48) ack 2064 win 32832 <nop,nop,timestamp 48942931
38279773>
0x0000: 4508 0064 2ef3 4000 3d06 f86b 0a23 0103 E..d.. at .=..k.#..
0x0010: 0a17 00f1 eada 0016 6284 63b5 5c06 97bb ........b.c.\...
0x0020: 8018 8040 413e 0000 0101 080a 02ea cf53 ... at A>.........S
0x0030: 0248 1a5d 9b63 e667 bd86 a333 8ee5 f061 .H.].c.g...3...a
0x0040: 5ec8 57e3 7017 f6ef e8ed 10ef 49ac dbec ^.W.p.......I...
0x0050: 569b fcc9 8ec7 f8f4 f0e5 6507 ec3a 5642 V.........e..:VB
0x0060: da05 1e81 ....
10:32:04.610317 IP (tos 0x8, ttl 64, id 1208, offset 0, flags [DF], proto:
TCP (6), length: 1420) 10.23.0.241.22 > 10.35.1.3.60122: . 2064:3432(1368)
ack 1666 win 32832 <nop,nop,timestamp 38279810 48942931>
0x0000: 4508 058c 04b8 4000 4006 1a7f 0a17 00f1 E..... at .@.......
0x0010: 0a23 0103 0016 eada 5c06 97bb 6284 63e5 .#......\...b.c.
0x0020: 8010 8040 8649 0000 0101 080a 0248 1a82 ... at .I.......H..
0x0030: 02ea cf53 1edd d5c1 9c1e bf5e 4271 6ac5 ...S.......^Bqj.
0x0040: feb1 a0a2 3b38 6f92 8c95 bb85 11aa 0824 ....;8o........$
0x0050: f6dd 1e9b 76f3 77e8 25c5 4da1 ec33 2d23 ....v.w.%.M..3-#
0x0060: b3ac ff52 2d2e b3b4 3e42 50a6 ff59 4b26 ...R-...>BP..YK&
0x0070: 355b 5[
10:32:04.610332 IP (tos 0x8, ttl 64, id 1209, offset 0, flags [DF], proto:
TCP (6), length: 1420) 10.23.0.241.22 > 10.35.1.3.60122: . 3432:4800(1368)
ack 1666 win 32832 <nop,nop,timestamp 38279810 48942931>
0x0000: 4508 058c 04b9 4000 4006 1a7e 0a17 00f1 E..... at .@..~....
0x0010: 0a23 0103 0016 eada 5c06 9d13 6284 63e5 .#......\...b.c.
0x0020: 8010 8040 6e32 0000 0101 080a 0248 1a82 ... at n2.......H..
0x0030: 02ea cf53 fd9c 908a 064d 14de 22de b6e2 ...S.....M.."...
0x0040: 41f6 c7cf c8e7 23ae 981e 9c6c 0f86 722f A.....#....l..r/
0x0050: 1c6b 6149 399c e1db da3c 550d a3ea f304 .kaI9....<U.....
0x0060: 6e0c 7c01 09e0 0054 662e ca50 b866 049d n.|....Tf..P.f..
0x0070: 6096 `.
10:32:04.610343 IP (tos 0x8, ttl 64, id 1210, offset 0, flags [DF], proto:
TCP (6), length: 1420) 10.23.0.241.22 > 10.35.1.3.60122: . 4800:6168(1368)
ack 1666 win 32832 <nop,nop,timestamp 38279810 48942931>
0x0000: 4508 058c 04ba 4000 4006 1a7d 0a17 00f1 E..... at .@..}....
0x0010: 0a23 0103 0016 eada 5c06 a26b 6284 63e5 .#......\..kb.c.
0x0020: 8010 8040 558e 0000 0101 080a 0248 1a82 ... at U........H..
0x0030: 02ea cf53 01b7 1c4d 52b4 eaba a6c1 388e ...S...MR.....8.
0x0040: 30f1 45ad b6e1 0f0f 14ec a64e 1189 dee7 0.E........N....
0x0050: b981 4113 da11 4ff2 f300 f06c 468f fbcc ..A...O....lF...
0x0060: e375 7934 c9f9 250c bdac 5bbd 0be6 b1e1 .uy4..%...[.....
0x0070: 32e0 2.
10:32:04.610351 IP (tos 0x8, ttl 64, id 1211, offset 0, flags [DF], proto:
TCP (6), length: 1420) 10.23.0.241.22 > 10.35.1.3.60122: . 6168:7536(1368)
ack 1666 win 32832 <nop,nop,timestamp 38279810 48942931>
0x0000: 4508 058c 04bb 4000 4006 1a7c 0a17 00f1 E..... at .@..|....
0x0010: 0a23 0103 0016 eada 5c06 a7c3 6284 63e5 .#......\...b.c.
0x0020: 8010 8040 0751 0000 0101 080a 0248 1a82 ... at .Q.......H..
0x0030: 02ea cf53 dc35 4a99 e94d 3f12 5285 f706 ...S.5J..M?.R...
0x0040: 69c9 ac60 8fe3 0065 df29 11a3 89d3 eb11 i..`...e.)......
0x0050: 7597 53d5 3764 8c01 d593 ff8f 273b bda1 u.S.7d......';..
0x0060: 477f b179 a2cc 4fd3 ceb8 2316 a831 bc4a G..y..O...#..1.J
0x0070: 10af ..
10:32:04.610457 IP (tos 0x8, ttl 64, id 1212, offset 0, flags [DF], proto:
TCP (6), length: 1420) 10.23.0.241.22 > 10.35.1.3.60122: . 7536:8904(1368)
ack 1666 win 32832 <nop,nop,timestamp 38279810 48942931>
0x0000: 4508 058c 04bc 4000 4006 1a7b 0a17 00f1 E..... at .@..{....
0x0010: 0a23 0103 0016 eada 5c06 ad1b 6284 63e5 .#......\...b.c.
0x0020: 8010 8040 a994 0000 0101 080a 0248 1a82 ... at .........H..
0x0030: 02ea cf53 7051 ecd2 2b26 f32b ee18 5d47 ...SpQ..+&.+..]G
0x0040: 6c48 cf69 8841 7861 ba2d 2d60 1dcc 732a lH.i.Axa.--`..s*
0x0050: f741 865f e78b 6954 a9c7 0724 3531 b418 .A._..iT...$51..
0x0060: f66c 6eb2 59fe 1598 c658 2b6f a777 2cb8 .ln.Y....X+o.w,.
0x0070: d7bb ..
here comes icmp frag packets. strange what sometimes tcpdump complains about
tcp header in icmp packet and sometimes not
10:32:04.612895 IP (tos 0x0, ttl 254, id 15170, offset 0, flags [none],
proto: ICMP (1), length: 56) 10.23.5.3 > 10.23.0.241: ICMP 10.35.1.3
unreachable - need to frag (mtu 1280), length 36
IP (tos 0x8, ttl 61, id 1208, offset 0, flags [DF], proto: TCP (6),
length: 1420) 10.23.0.241.22 > 10.35.1.3.60122: tcp 1396 [bad hdr length 4
- too short, < 20]
0x0000: 4500 0038 3b42 0000 fe01 6761 0a17 0503 E..8;B....ga....
0x0010: 0a17 00f1 0304 479f 0000 0500 4508 058c ......G.....E...
0x0020: 04b8 4000 3d06 1d7f 0a17 00f1 0a23 0103 .. at .=........#..
0x0030: 0016 eada c207 0364 .......d
10:32:04.896541 IP (tos 0x8, ttl 64, id 1213, offset 0, flags [DF], proto:
TCP (6), length: 1420) 10.23.0.241.22 > 10.35.1.3.60122: . 2064:3432(1368)
ack 1666 win 32832 <nop,nop,timestamp 38280096 48942931>
0x0000: 4508 058c 04bd 4000 4006 1a7a 0a17 00f1 E..... at .@..z....
0x0010: 0a23 0103 0016 eada 5c06 97bb 6284 63e5 .#......\...b.c.
0x0020: 8010 8040 852b 0000 0101 080a 0248 1ba0 ... at .+.......H..
0x0030: 02ea cf53 1edd d5c1 9c1e bf5e 4271 6ac5 ...S.......^Bqj.
0x0040: feb1 a0a2 3b38 6f92 8c95 bb85 11aa 0824 ....;8o........$
0x0050: f6dd 1e9b 76f3 77e8 25c5 4da1 ec33 2d23 ....v.w.%.M..3-#
0x0060: b3ac ff52 2d2e b3b4 3e42 50a6 ff59 4b26 ...R-...>BP..YK&
0x0070: 355b 5[
10:32:05.269815 IP (tos 0x8, ttl 64, id 1228, offset 0, flags [DF], proto:
TCP (6), length: 1420) 10.23.0.241.22 > 10.35.1.3.60122: . 2064:3432(1368)
ack 1666 win 32832 <nop,nop,timestamp 38280468 48942931>
0x0000: 4508 058c 04cc 4000 4006 1a6b 0a17 00f1 E..... at .@..k....
0x0010: 0a23 0103 0016 eada 5c06 97bb 6284 63e5 .#......\...b.c.
0x0020: 8010 8040 83b7 0000 0101 080a 0248 1d14 ... at .........H..
0x0030: 02ea cf53 1edd d5c1 9c1e bf5e 4271 6ac5 ...S.......^Bqj.
0x0040: feb1 a0a2 3b38 6f92 8c95 bb85 11aa 0824 ....;8o........$
0x0050: f6dd 1e9b 76f3 77e8 25c5 4da1 ec33 2d23 ....v.w.%.M..3-#
0x0060: b3ac ff52 2d2e b3b4 3e42 50a6 ff59 4b26 ...R-...>BP..YK&
0x0070: 355b 5[
10:32:05.272005 IP (tos 0x0, ttl 254, id 15172, offset 0, flags [none],
proto: ICMP (1), length: 56) 10.23.5.3 > 10.23.0.241: ICMP 10.35.1.3
unreachable - need to frag (mtu 1280), length 36
IP (tos 0x8, ttl 61, id 1228, offset 0, flags [DF], proto: TCP (6),
length: 1420) 10.23.0.241.22 > 10.35.1.3.60122: [|tcp]
0x0000: 4500 0038 3b44 0000 fe01 675f 0a17 0503 E..8;D....g_....
0x0010: 0a17 00f1 0304 479f 0000 0500 4508 058c ......G.....E...
0x0020: 04cc 4000 3d06 1d6b 0a17 00f1 0a23 0103 .. at .=..k.....#..
0x0030: 0016 eada c207 0364 .......d
10:32:05.815720 IP (tos 0x8, ttl 64, id 1229, offset 0, flags [DF], proto:
TCP (6), length: 1420) 10.23.0.241.22 > 10.35.1.3.60122: . 2064:3432(1368)
ack 1666 win 32832 <nop,nop,timestamp 38281012 48942931>
0x0000: 4508 058c 04cd 4000 4006 1a6a 0a17 00f1 E..... at .@..j....
0x0010: 0a23 0103 0016 eada 5c06 97bb 6284 63e5 .#......\...b.c.
0x0020: 8010 8040 8197 0000 0101 080a 0248 1f34 ... at .........H.4
0x0030: 02ea cf53 1edd d5c1 9c1e bf5e 4271 6ac5 ...S.......^Bqj.
0x0040: feb1 a0a2 3b38 6f92 8c95 bb85 11aa 0824 ....;8o........$
0x0050: f6dd 1e9b 76f3 77e8 25c5 4da1 ec33 2d23 ....v.w.%.M..3-#
0x0060: b3ac ff52 2d2e b3b4 3e42 50a6 ff59 4b26 ...R-...>BP..YK&
0x0070: 355b 5[
10:32:05.817488 IP (tos 0x0, ttl 254, id 15174, offset 0, flags [none],
proto: ICMP (1), length: 56) 10.23.5.3 > 10.23.0.241: ICMP 10.35.1.3
unreachable - need to frag (mtu 1280), length 36
IP (tos 0x8, ttl 61, id 1229, offset 0, flags [DF], proto: TCP (6),
length: 1420) 10.23.0.241.22 > 10.35.1.3.60122: tcp 1400 [bad hdr length 0
- too short, < 20]
0x0000: 4500 0038 3b46 0000 fe01 675d 0a17 0503 E..8;F....g]....
0x0010: 0a17 00f1 0304 479f 0000 0500 4508 058c ......G.....E...
0x0020: 04cd 4000 3d06 1d6a 0a17 00f1 0a23 0103 .. at .=..j.....#..
0x0030: 0016 eada c207 0364 .......d
10:32:06.706827 IP (tos 0x8, ttl 64, id 1234, offset 0, flags [DF], proto:
TCP (6), length: 1420) 10.23.0.241.22 > 10.35.1.3.60122: . 2064:3432(1368)
ack 1666 win 32832 <nop,nop,timestamp 38281900 48942931>
0x0000: 4508 058c 04d2 4000 4006 1a65 0a17 00f1 E..... at .@..e....
0x0010: 0a23 0103 0016 eada 5c06 97bb 6284 63e5 .#......\...b.c.
0x0020: 8010 8040 7e1f 0000 0101 080a 0248 22ac ...@~........H".
0x0030: 02ea cf53 1edd d5c1 9c1e bf5e 4271 6ac5 ...S.......^Bqj.
0x0040: feb1 a0a2 3b38 6f92 8c95 bb85 11aa 0824 ....;8o........$
0x0050: f6dd 1e9b 76f3 77e8 25c5 4da1 ec33 2d23 ....v.w.%.M..3-#
0x0060: b3ac ff52 2d2e b3b4 3e42 50a6 ff59 4b26 ...R-...>BP..YK&
0x0070: 355b 5[
10:32:06.708954 IP (tos 0x0, ttl 254, id 15182, offset 0, flags [none],
proto: ICMP (1), length: 56) 10.23.5.3 > 10.23.0.241: ICMP 10.35.1.3
unreachable - need to frag (mtu 1280), length 36
IP (tos 0x8, ttl 61, id 1234, offset 0, flags [DF], proto: TCP (6),
length: 1420) 10.23.0.241.22 > 10.35.1.3.60122: [|tcp]
0x0000: 4500 0038 3b4e 0000 fe01 6755 0a17 0503 E..8;N....gU....
0x0010: 0a17 00f1 0304 479f 0000 0500 4508 058c ......G.....E...
0x0020: 04d2 4000 3d06 1d65 0a17 00f1 0a23 0103 .. at .=..e.....#..
0x0030: 0016 eada c207 0364 .......d
10:32:08.288344 IP (tos 0x8, ttl 64, id 1236, offset 0, flags [DF], proto:
TCP (6), length: 1420) 10.23.0.241.22 > 10.35.1.3.60122: . 2064:3432(1368)
ack 1666 win 32832 <nop,nop,timestamp 38283476 48942931>
0x0000: 4508 058c 04d4 4000 4006 1a63 0a17 00f1 E..... at .@..c....
0x0010: 0a23 0103 0016 eada 5c06 97bb 6284 63e5 .#......\...b.c.
0x0020: 8010 8040 77f7 0000 0101 080a 0248 28d4 ... at w........H(.
0x0030: 02ea cf53 1edd d5c1 9c1e bf5e 4271 6ac5 ...S.......^Bqj.
0x0040: feb1 a0a2 3b38 6f92 8c95 bb85 11aa 0824 ....;8o........$
0x0050: f6dd 1e9b 76f3 77e8 25c5 4da1 ec33 2d23 ....v.w.%.M..3-#
0x0060: b3ac ff52 2d2e b3b4 3e42 50a6 ff59 4b26 ...R-...>BP..YK&
0x0070: 355b 5[
10:32:08.333302 IP (tos 0x0, ttl 254, id 15201, offset 0, flags [none],
proto: ICMP (1), length: 56) 10.23.5.3 > 10.23.0.241: ICMP 10.35.1.3
unreachable - need to frag (mtu 1280), length 36
IP (tos 0x8, ttl 61, id 1236, offset 0, flags [DF], proto: TCP (6),
length: 1420) 10.23.0.241.22 > 10.35.1.3.60122: [|tcp]
0x0000: 4500 0038 3b61 0000 fe01 6742 0a17 0503 E..8;a....gB....
0x0010: 0a17 00f1 0304 479f 0000 0500 4508 058c ......G.....E...
0x0020: 04d4 4000 3d06 1d63 0a17 00f1 0a23 0103 .. at .=..c.....#..
0x0030: 0016 eada c207 0364 .......d
10:32:10.262231 IP (tos 0x8, ttl 64, id 1238, offset 0, flags [DF], proto:
TCP (6), length: 1420) 10.23.0.241.22 > 10.35.1.3.60122: . 2064:3432(1368)
ack 1666 win 32832 <nop,nop,timestamp 38285436 48942931>
0x0000: 4508 058c 04d6 4000 4006 1a61 0a17 00f1 E..... at .@..a....
0x0010: 0a23 0103 0016 eada 5c06 97bb 6284 63e5 .#......\...b.c.
0x0020: 8010 8040 704f 0000 0101 080a 0248 307c ... at pO.......H0|
0x0030: 02ea cf53 1edd d5c1 9c1e bf5e 4271 6ac5 ...S.......^Bqj.
0x0040: feb1 a0a2 3b38 6f92 8c95 bb85 11aa 0824 ....;8o........$
0x0050: f6dd 1e9b 76f3 77e8 25c5 4da1 ec33 2d23 ....v.w.%.M..3-#
0x0060: b3ac ff52 2d2e b3b4 3e42 50a6 ff59 4b26 ...R-...>BP..YK&
0x0070: 355b 5[
10:32:10.264081 IP (tos 0x0, ttl 254, id 15210, offset 0, flags [none],
proto: ICMP (1), length: 56) 10.23.5.3 > 10.23.0.241: ICMP 10.35.1.3
unreachable - need to frag (mtu 1280), length 36
IP (tos 0x8, ttl 61, id 1238, offset 0, flags [DF], proto: TCP (6),
length: 1420) 10.23.0.241.22 > 10.35.1.3.60122: [|tcp]
0x0000: 4500 0038 3b6a 0000 fe01 6739 0a17 0503 E..8;j....g9....
0x0010: 0a17 00f1 0304 479f 0000 0500 4508 058c ......G.....E...
0x0020: 04d6 4000 3d06 1d61 0a17 00f1 0a23 0103 .. at .=..a.....#..
0x0030: 0016 eada c207 0364 .......d
10:32:10.490936 IP (tos 0x8, ttl 61, id 12360, offset 0, flags [DF], proto:
TCP (6), length: 52) 10.35.1.3.60122 > 10.23.0.241.22: F, cksum 0x4a03
(correct), 1666:1666(0) ack 2064 win 32832 <nop,nop,timestamp 48943519
38279773>
0x0000: 4508 0034 3048 4000 3d06 f746 0a23 0103 E..40H at .=..F.#..
0x0010: 0a17 00f1 eada 0016 6284 63e5 5c06 97bb ........b.c.\...
0x0020: 8011 8040 4a03 0000 0101 080a 02ea d19f ... at J...........
0x0030: 0248 1a5d .H.]
10:32:10.490953 IP (tos 0x8, ttl 64, id 1239, offset 0, flags [DF], proto:
TCP (6), length: 1420) 10.23.0.241.22 > 10.35.1.3.60122: . 3432:4800(1368)
ack 1666 win 32832 <nop,nop,timestamp 38285663 48943519>
0x0000: 4508 058c 04d7 4000 4006 1a60 0a17 00f1 E..... at .@..`....
0x0010: 0a23 0103 0016 eada 5c06 9d13 6284 63e5 .#......\...b.c.
0x0020: 8010 8040 5509 0000 0101 080a 0248 315f ... at U........H1_
0x0030: 02ea d19f fd9c 908a 064d 14de 22de b6e2 .........M.."...
0x0040: 41f6 c7cf c8e7 23ae 981e 9c6c 0f86 722f A.....#....l..r/
0x0050: 1c6b 6149 399c e1db da3c 550d a3ea f304 .kaI9....<U.....
0x0060: 6e0c 7c01 09e0 0054 662e ca50 b866 049d n.|....Tf..P.f..
0x0070: 6096 `.
10:32:10.883503 IP (tos 0x8, ttl 61, id 12400, offset 0, flags [DF], proto:
TCP (6), length: 52) 10.35.1.3.60122 > 10.23.0.241.22: F, cksum 0x49db
(correct), 1666:1666(0) ack 2064 win 32832 <nop,nop,timestamp 48943559
38279773>
0x0000: 4508 0034 3070 4000 3d06 f71e 0a23 0103 E..40p at .=....#..
0x0010: 0a17 00f1 eada 0016 6284 63e5 5c06 97bb ........b.c.\...
0x0020: 8011 8040 49db 0000 0101 080a 02ea d1c7 ... at I...........
0x0030: 0248 1a5d .H.]
10:32:10.883517 IP (tos 0x8, ttl 64, id 1240, offset 0, flags [DF], proto:
TCP (6), length: 1420) 10.23.0.241.22 > 10.35.1.3.60122: . 4800:6168(1368)
ack 1666 win 32832 <nop,nop,timestamp 38286055 48943559>
0x0000: 4508 058c 04d8 4000 4006 1a5f 0a17 00f1 E..... at .@.._....
0x0010: 0a23 0103 0016 eada 5c06 a26b 6284 63e5 .#......\..kb.c.
0x0020: 8010 8040 3ab5 0000 0101 080a 0248 32e7 ...@:........H2.
0x0030: 02ea d1c7 01b7 1c4d 52b4 eaba a6c1 388e .......MR.....8.
0x0040: 30f1 45ad b6e1 0f0f 14ec a64e 1189 dee7 0.E........N....
0x0050: b981 4113 da11 4ff2 f300 f06c 468f fbcc ..A...O....lF...
0x0060: e375 7934 c9f9 250c bdac 5bbd 0be6 b1e1 .uy4..%...[.....
0x0070: 32e0 2.
10:32:10.883525 IP (tos 0x8, ttl 64, id 1241, offset 0, flags [DF], proto:
TCP (6), length: 1420) 10.23.0.241.22 > 10.35.1.3.60122: . 6168:7536(1368)
ack 1666 win 32832 <nop,nop,timestamp 38286055 48943559>
0x0000: 4508 058c 04d9 4000 4006 1a5e 0a17 00f1 E..... at .@..^....
0x0010: 0a23 0103 0016 eada 5c06 a7c3 6284 63e5 .#......\...b.c.
0x0020: 8010 8040 ec77 0000 0101 080a 0248 32e7 ... at .w.......H2.
0x0030: 02ea d1c7 dc35 4a99 e94d 3f12 5285 f706 .....5J..M?.R...
0x0040: 69c9 ac60 8fe3 0065 df29 11a3 89d3 eb11 i..`...e.)......
0x0050: 7597 53d5 3764 8c01 d593 ff8f 273b bda1 u.S.7d......';..
0x0060: 477f b179 a2cc 4fd3 ceb8 2316 a831 bc4a G..y..O...#..1.J
0x0070: 10af ..
10:32:10.885801 IP (tos 0x0, ttl 254, id 15215, offset 0, flags [none],
proto: ICMP (1), length: 56) 10.23.5.3 > 10.23.0.241: ICMP 10.35.1.3
unreachable - need to frag (mtu 1280), length 36
IP (tos 0x8, ttl 61, id 1240, offset 0, flags [DF], proto: TCP (6),
length: 1420) 10.23.0.241.22 > 10.35.1.3.60122: [|tcp]
0x0000: 4500 0038 3b6f 0000 fe01 6734 0a17 0503 E..8;o....g4....
0x0010: 0a17 00f1 0304 3cef 0000 0500 4508 058c ......<.....E...
0x0020: 04d8 4000 3d06 1d5f 0a17 00f1 0a23 0103 .. at .=.._.....#..
0x0030: 0016 eada c207 0e14 ........
here i cancelled
10:32:11.484055 IP (tos 0x8, ttl 61, id 12413, offset 0, flags [DF], proto:
TCP (6), length: 52) 10.35.1.3.60122 > 10.23.0.241.22: F, cksum 0x499f
(correct), 1666:1666(0) ack 2064 win 32832 <nop,nop,timestamp 48943619
38279773>
0x0000: 4508 0034 307d 4000 3d06 f711 0a23 0103 E..40}@.=....#..
0x0010: 0a17 00f1 eada 0016 6284 63e5 5c06 97bb ........b.c.\...
0x0020: 8011 8040 499f 0000 0101 080a 02ea d203 ... at I...........
0x0030: 0248 1a5d .H.]
turning PathMTU off or reducing mtu on interface helps, but what the hell?
what's wrong whith that?
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