[Bug 253476] ipfw keepalive: tcp_do_segment: Timestamp missing, segment silently dropped

bugzilla-noreply at freebsd.org bugzilla-noreply at freebsd.org
Sat Feb 13 15:58:25 UTC 2021


https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=253476

Richard Scheffenegger <rscheff at freebsd.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rscheff at freebsd.org
           Assignee|ipfw at FreeBSD.org            |rscheff at freebsd.org
             Status|New                         |In Progress

--- Comment #1 from Richard Scheffenegger <rscheff at freebsd.org> ---
Looking into this; without the tolerate_missing_ts, using the TCP_NOOPT socket
option would also result in sessions not being set up:

 nc --no-tcpopt -l 10.0.0.101 12345 &
 nc -s 10.0.0.102 10.0.0.101 12345

The server side would respond without timestamp, and even so it was not yet
negotiated, the client would apparently request the SYN,ACK missing the TS...



16:48:10.515731 IP 10.0.0.102.46343 > 10.0.0.101.12345: Flags [S], seq
1670959926, win 65535, options [mss 16344,nop,wscale 6,sackOK,TS val 1505575656
ecr 0], length 0
16:48:10.515908 IP 10.0.0.101.12345 > 10.0.0.102.46343: Flags [S.], seq
3686780973, ack 1670959927, win 65535, length 0
16:48:10.515959 IP 10.0.0.102.46343 > 10.0.0.101.12345: Flags [.], ack 1, win
65535, length 0
16:48:11.514681 IP 10.0.0.101.12345 > 10.0.0.102.46343: Flags [S.], seq
3686780973, ack 1670959927, win 65535, length 0
16:48:11.514829 IP 10.0.0.102.46343 > 10.0.0.101.12345: Flags [.], ack 1, win
65535, length 0
16:48:13.713713 IP 10.0.0.101.12345 > 10.0.0.102.46343: Flags [S.], seq
3686780973, ack 1670959927, win 65535, length 0
16:48:13.713975 IP 10.0.0.102.46343 > 10.0.0.101.12345: Flags [.], ack 1, win
65535, length 0
16:48:17.916016 IP 10.0.0.101.12345 > 10.0.0.102.46343: Flags [S.], seq
3686780973, ack 1670959927, win 65535, length 0
16:48:17.917153 IP 10.0.0.102.46343 > 10.0.0.101.12345: Flags [.], ack 1, win
65535, length 0
16:48:58.977772 IP 10.0.0.102.46343 > 10.0.0.101.12345: Flags [.], ack 1, win
0, length 0
16:48:58.979551 IP 10.0.0.101.12345 > 10.0.0.102.46343: Flags [R], seq
3686780974, win 0, length 0


For the reported issue, this doesn't appear to be ipfw related per se,
the persist / keepalive segemtns are being sent without TS, even though TS was
negotiated:


16:26:39.655911 IP 10.0.0.102.43262 > 10.0.0.101.12345: Flags [S], seq
1299597894, win 65535, options [mss 16344,nop,wscale 6,sackOK,TS val 3308112659
ecr 0], length 0
16:26:39.656269 IP 10.0.0.101.12345 > 10.0.0.102.43262: Flags [S.], seq
3229957175, ack 1299597895, win 65535, options [mss 16344,nop,wscale
6,sackOK,TS val 2214622743 ecr 3308112659], length 0
16:26:39.656370 IP 10.0.0.102.43262 > 10.0.0.101.12345: Flags [.], ack 1, win
1277, options [nop,nop,TS val 3308112659 ecr 2214622743], length 0

16:27:23.455682 IP 10.0.0.102.43262 > 10.0.0.101.12345: Flags [.], ack 1, win
0, length 0 ## should have the TS option too.
16:27:28.456635 IP 10.0.0.102.43262 > 10.0.0.101.12345: Flags [.], ack 1, win
0, length 0
16:27:33.453985 IP 10.0.0.102.43262 > 10.0.0.101.12345: Flags [.], ack 1, win
0, length 0
16:27:38.456062 IP 10.0.0.102.43262 > 10.0.0.101.12345: Flags [.], ack 1, win
0, length 0
16:28:06.343812 IP 10.0.0.102.43262 > 10.0.0.101.12345: Flags [F.], seq 1, ack
1, win 1277, options [nop,nop,TS val 3308199350 ecr 2214622743], length 0
16:28:06.344116 IP 10.0.0.101.12345 > 10.0.0.102.43262: Flags [.], ack 2, win
1277, options [nop,nop,TS val 2214709434 ecr 3308199350], length 0
16:28:06.344363 IP 10.0.0.101.12345 > 10.0.0.102.43262: Flags [F.], seq 1, ack
2, win 1277, options [nop,nop,TS val 2214709434 ecr 3308199350], length 0
16:28:06.344419 IP 10.0.0.102.43262 > 10.0.0.101.12345: Flags [.], ack 2, win
1276, options [nop,nop,TS val 3308199350 ecr 2214709434], length 0

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