On Tue, 2015-05-26 at 22:47 -0700, Gopakumar Choorakkot Edakkunni wrote: > All, > > The original query I had posted is here : > http://stackoverflow.com/questions/30414350/tcp-syn-ack-tsecr-not-matching-tsval-in-syn > .. The summary is that once in a while, the TSval in SYN is not what > is getting echoed in TSecr, and looks like something on amazon aws > side is very strict about that and drops those packets. Any clues on > this - whether its a known issue/fixed elsewhere etc. would be of > great help.
I guess that if you send SYN packets 3 times as your email did on netdev, that might cause some issues... More seriously, server has a SYN_RECV socket with same tuple, because of a SYN sent earlier : 8:36:00.593136 IP XX.YY.ZZ.VV.24548 > AA.BB.CC.DD.443: Flags [S], seq 1204544933, win 29200, options [mss 1320,sackOK,TS val 6032576 ecr 0,nop,wscale 7], length 0 18:36:00.593171 IP AA.BB.CC.DD.443 > XX.YY.ZZ.VV.24548: Flags [S.], seq 986069863, ack 1204544934, win 14480, options [mss 1460,sackOK,TS val 180940028 ecr 6001497,nop,wscale 5], length 0 18:36:00.992699 IP AA.BB.CC.DD.443 > XX.YY.ZZ.VV.24548: Flags [S.], seq 986069863, ack 1204544934, win 14480, options [mss 1460,sackOK,TS val 180940128 ecr 6001497,nop,wscale 5], length 0 >From these traces, we can guess a SYN packet was sent about 31 seconds earlier. SYNACK rtx do not update the TSECR : Initial SYN TSval value (6001497) is mirrored. Are you establishing many active sessions per minute to this particular target ? -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
