Date: Mon, 24 Aug 2009 17:36:08 +0300 From: Nikolay Denev <ndenev@gmail.com> To: freebsd-net@freebsd.org Subject: 7.2 sends broken TCP retransmits while in half-closed state? Message-ID: <6C253DEA-0C34-4109-9D45-3DE1750DB1BE@gmail.com>
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Hello,
Today while I was diagnosing a FTP problem which turned out to be EPSV =20=
issue I
found some very interesting things in the tcpdumps.
=46rom what I understand from the trace, after a few retransmits, the =20=
client side
sends FIN/ACK to close the connection, and receives ACK.
But while waiting for the remote side to send it's FIN/ACK to be =20
ACK'ed, it continues
to send the retransmits that it did before the first FIN/ACK, but they =20=
are now truncated.
Here is the exported trace from Wireshark. I can also send it in =20
tcpdump output format if someone prefers it.
10.10.0.10 is the client IP.
10.20.0.20 is the server IP.
Look for the "Destination Unreachable" messages generated by the =20
broken retransmits.
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 65073 (65073), Dst Port: ftp =20=
(21), Seq: 47, Ack: 248, Len: 0
No. Time Source Destination =20
Protocol Info
23 11.930506 10.10.0.10 10.20.0.20 FTP =20
Request: EPSV
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 65073 (65073), Dst Port: ftp =20=
(21), Seq: 47, Ack: 248, Len: 6
File Transfer Protocol (FTP)
No. Time Source Destination =20
Protocol Info
24 11.987691 10.20.0.20 10.10.0.10 FTP =20
Response: 229 Entering Extended Passive Mode (|||59364|)
Internet Protocol, Src: 10.20.0.20 (10.20.0.20), Dst: 10.10.0.10 =20
(10.10.0.10)
Transmission Control Protocol, Src Port: ftp (21), Dst Port: 65073 =20
(65073), Seq: 248, Ack: 53, Len: 48
File Transfer Protocol (FTP)
No. Time Source Destination =20
Protocol Info
25 11.987770 10.10.0.10 10.20.0.20 TCP =20
62552 > 59364 [SYN] Seq=3D0 Win=3D65535 Len=3D0 MSS=3D1460 WS=3D3 =
TSV=3D2276550531 =20
TSER=3D0
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 62552 (62552), Dst Port: =20
59364 (59364), Seq: 0, Len: 0
No. Time Source Destination =20
Protocol Info
26 12.087485 10.10.0.10 10.20.0.20 TCP =20
65073 > ftp [ACK] Seq=3D53 Ack=3D296 Win=3D66608 Len=3D0 TSV=3D2276550631 =
=20
TSER=3D3200765949
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 65073 (65073), Dst Port: ftp =20=
(21), Seq: 53, Ack: 296, Len: 0
No. Time Source Destination =20
Protocol Info
27 14.987564 10.10.0.10 10.20.0.20 TCP =20
62552 > 59364 [SYN] Seq=3D0 Win=3D65535 Len=3D0 MSS=3D1460 WS=3D3 =
TSV=3D2276553531 =20
TSER=3D0
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 62552 (62552), Dst Port: =20
59364 (59364), Seq: 0, Len: 0
No. Time Source Destination =20
Protocol Info
28 18.187647 10.10.0.10 10.20.0.20 TCP =20
62552 > 59364 [SYN] Seq=3D0 Win=3D65535 Len=3D0 MSS=3D1460 WS=3D3 =
TSV=3D2276556731 =20
TSER=3D0
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 62552 (62552), Dst Port: =20
59364 (59364), Seq: 0, Len: 0
No. Time Source Destination =20
Protocol Info
29 21.387724 10.10.0.10 10.20.0.20 TCP =20
62552 > 59364 [SYN] Seq=3D0 Win=3D65535 Len=3D0 MSS=3D1460
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 62552 (62552), Dst Port: =20
59364 (59364), Seq: 0, Len: 0
No. Time Source Destination =20
Protocol Info
30 24.587802 10.10.0.10 10.20.0.20 TCP =20
62552 > 59364 [SYN] Seq=3D0 Win=3D65535 Len=3D0 MSS=3D1460
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 62552 (62552), Dst Port: =20
59364 (59364), Seq: 0, Len: 0
No. Time Source Destination =20
Protocol Info
31 27.787885 10.10.0.10 10.20.0.20 TCP =20
62552 > 59364 [SYN] Seq=3D0 Win=3D65535 Len=3D0 MSS=3D1460
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 62552 (62552), Dst Port: =20
59364 (59364), Seq: 0, Len: 0
No. Time Source Destination =20
Protocol Info
32 33.988042 10.10.0.10 10.20.0.20 TCP =20
62552 > 59364 [SYN] Seq=3D0 Win=3D65535 Len=3D0 MSS=3D1460
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 62552 (62552), Dst Port: =20
59364 (59364), Seq: 0, Len: 0
No. Time Source Destination =20
Protocol Info
33 46.188343 10.10.0.10 10.20.0.20 TCP =20
62552 > 59364 [SYN] Seq=3D0 Win=3D65535 Len=3D0 MSS=3D1460
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 62552 (62552), Dst Port: =20
59364 (59364), Seq: 0, Len: 0
No. Time Source Destination =20
Protocol Info
34 70.388952 10.10.0.10 10.20.0.20 TCP =20
62552 > 59364 [SYN] Seq=3D0 Win=3D65535 Len=3D0 MSS=3D1460
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 62552 (62552), Dst Port: =20
59364 (59364), Seq: 0, Len: 0
No. Time Source Destination =20
Protocol Info
35 86.989453 10.10.0.10 10.20.0.20 FTP =20
Request: EPRT |1|10.10.0.10|49610|
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 65073 (65073), Dst Port: ftp =20=
(21), Seq: 53, Ack: 296, Len: 31
File Transfer Protocol (FTP)
No. Time Source Destination =20
Protocol Info
36 87.287370 10.10.0.10 10.20.0.20 FTP =20
[TCP Retransmission] Request: EPRT |1|10.10.0.10|49610|
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 65073 (65073), Dst Port: ftp =20=
(21), Seq: 53, Ack: 296, Len: 31
File Transfer Protocol (FTP)
No. Time Source Destination =20
Protocol Info
37 87.683379 10.10.0.10 10.20.0.20 FTP =20
[TCP Retransmission] Request: EPRT |1|10.10.0.10|49610|
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 65073 (65073), Dst Port: ftp =20=
(21), Seq: 53, Ack: 296, Len: 31
File Transfer Protocol (FTP)
No. Time Source Destination =20
Protocol Info
38 88.275395 10.10.0.10 10.20.0.20 FTP =20
[TCP Retransmission] Request: EPRT |1|10.10.0.10|49610|
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 65073 (65073), Dst Port: ftp =20=
(21), Seq: 53, Ack: 296, Len: 31
File Transfer Protocol (FTP)
No. Time Source Destination =20
Protocol Info
39 89.259423 10.10.0.10 10.20.0.20 FTP =20
[TCP Retransmission] Request: EPRT |1|10.10.0.10|49610|
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 65073 (65073), Dst Port: ftp =20=
(21), Seq: 53, Ack: 296, Len: 31
File Transfer Protocol (FTP)
No. Time Source Destination =20
Protocol Info
40 91.027467 10.10.0.10 10.20.0.20 FTP =20
[TCP Retransmission] Request: EPRT |1|10.10.0.10|49610|
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 65073 (65073), Dst Port: ftp =20=
(21), Seq: 53, Ack: 296, Len: 31
File Transfer Protocol (FTP)
No. Time Source Destination =20
Protocol Info
41 92.859511 10.10.0.10 10.20.0.20 FTP =20
[TCP Retransmission] Request: EPRT |1|10.10.0.10|49610|
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 65073 (65073), Dst Port: ftp =20=
(21), Seq: 53, Ack: 296, Len: 31
File Transfer Protocol (FTP)
No. Time Source Destination =20
Protocol Info
42 96.323600 10.10.0.10 10.20.0.20 FTP =20
[TCP Retransmission] Request: EPRT |1|10.10.0.10|49610|
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 65073 (65073), Dst Port: ftp =20=
(21), Seq: 53, Ack: 296, Len: 31
File Transfer Protocol (FTP)
No. Time Source Destination =20
Protocol Info
43 103.051770 10.10.0.10 10.20.0.20 FTP =20
[TCP Retransmission] Request: EPRT |1|10.10.0.10|49610|
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 65073 (65073), Dst Port: ftp =20=
(21), Seq: 53, Ack: 296, Len: 31
File Transfer Protocol (FTP)
No. Time Source Destination =20
Protocol Info
44 116.308102 10.10.0.10 10.20.0.20 FTP =20
[TCP Retransmission] Request: EPRT |1|10.10.0.10|49610|
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 65073 (65073), Dst Port: ftp =20=
(21), Seq: 53, Ack: 296, Len: 31
File Transfer Protocol (FTP)
No. Time Source Destination =20
Protocol Info
45 142.620762 10.10.0.10 10.20.0.20 FTP =20
[TCP Retransmission] Request: EPRT |1|10.10.0.10|49610|
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 65073 (65073), Dst Port: ftp =20=
(21), Seq: 53, Ack: 296, Len: 31
File Transfer Protocol (FTP)
No. Time Source Destination =20
Protocol Info
46 146.991908 10.10.0.10 10.20.0.20 TCP =20
65073 > ftp [FIN, ACK] Seq=3D84 Ack=3D296 Win=3D66608 Len=3D0 =
TSV=3D2276685532 =20
TSER=3D3200765949
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 65073 (65073), Dst Port: ftp =20=
(21), Seq: 84, Ack: 296, Len: 0
No. Time Source Destination =20
Protocol Info
47 147.049585 10.20.0.20 10.10.0.10 TCP ftp =20=
> 65073 [ACK] Seq=3D296 Ack=3D65 Win=3D5792 Len=3D0 TSV=3D3200901032 =20=
TSER=3D2276550631 SLE=3D72 SRE=3D73
Internet Protocol, Src: 10.20.0.20 (10.20.0.20), Dst: 10.10.0.10 =20
(10.10.0.10)
Transmission Control Protocol, Src Port: ftp (21), Dst Port: 65073 =20
(65073), Seq: 296, Ack: 65, Len: 0
No. Time Source Destination =20
Protocol Info
48 211.050479 10.10.0.10 10.20.0.20 FTP =20
[TCP Retransmission] Request: 10.0.10|49610|
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 65073 (65073), Dst Port: ftp =20=
(21), Seq: 65, Ack: 296, Len: 19
File Transfer Protocol (FTP)
No. Time Source Destination =20
Protocol Info
49 211.118136 10.20.0.20 10.10.0.10 ICMP =20
Destination unreachable (Host administratively prohibited)
Internet Protocol, Src: 10.20.0.20 (10.20.0.20), Dst: 10.10.0.10 =20
(10.10.0.10)
Internet Control Message Protocol
No. Time Source Destination =20
Protocol Info
50 275.052084 10.10.0.10 10.20.0.20 FTP =20
[TCP Retransmission] Request: 10.0.10|49610|
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 65073 (65073), Dst Port: ftp =20=
(21), Seq: 65, Ack: 296, Len: 19
File Transfer Protocol (FTP)
No. Time Source Destination =20
Protocol Info
51 275.105225 10.20.0.20 10.10.0.10 ICMP =20
Destination unreachable (Host administratively prohibited)
Internet Protocol, Src: 10.20.0.20 (10.20.0.20), Dst: 10.10.0.10 =20
(10.10.0.10)
Internet Control Message Protocol
No. Time Source Destination =20
Protocol Info
52 299.988028 10.20.0.20 10.10.0.10 FTP =20
Response: 421 No Transfer Timeout (300 seconds): closing control =20
connection.
Internet Protocol, Src: 10.20.0.20 (10.20.0.20), Dst: 10.10.0.10 =20
(10.10.0.10)
Transmission Control Protocol, Src Port: ftp (21), Dst Port: 65073 =20
(65073), Seq: 296, Ack: 65, Len: 68
File Transfer Protocol (FTP)
No. Time Source Destination =20
Protocol Info
53 299.988051 10.10.0.10 10.20.0.20 TCP =20
65073 > ftp [RST] Seq=3D65 Win=3D0 Len=3D0
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 65073 (65073), Dst Port: ftp =20=
(21), Seq: 65, Len: 0
No. Time Source Destination =20
Protocol Info
54 299.988053 10.20.0.20 10.10.0.10 TCP ftp =20=
> 65073 [FIN, ACK] Seq=3D364 Ack=3D65 Win=3D5792 Len=3D0 TSV=3D3201053996=
=20
TSER=3D2276550631 SLE=3D72 SRE=3D73
Internet Protocol, Src: 10.20.0.20 (10.20.0.20), Dst: 10.10.0.10 =20
(10.10.0.10)
Transmission Control Protocol, Src Port: ftp (21), Dst Port: 65073 =20
(65073), Seq: 364, Ack: 65, Len: 0
No. Time Source Destination =20
Protocol Info
55 299.988060 10.10.0.10 10.20.0.20 TCP =20
65073 > ftp [RST] Seq=3D65 Win=3D0 Len=3D0
Internet Protocol, Src: 10.10.0.10 (10.10.0.10), Dst: 10.20.0.20 =20
(10.20.0.20)
Transmission Control Protocol, Src Port: 65073 (65073), Dst Port: ftp =20=
(21), Seq: 65, Len: 0
No. Time Source Destination =20
Protocol Info
56 300.041497 10.20.0.20 10.10.0.10 ICMP =20
Destination unreachable (Host administratively prohibited)
- --
Regards,
Nikolay Denev
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