Linux dmesg中关于TCP: Treason uncloaked!信息
在debian Linux服务器的日志中,dmesg出现类似的信息:
TCP: Treason uncloaked! Peer 202.106.38.7:57824/80 shrinks window 3573023813:3573023814. Repaired.
TCP: Treason uncloaked! Peer 202.106.38.7:57824/80 shrinks window 3573023813:3573023814. Repaired.
TCP: Treason uncloaked! Peer 202.99.99.211:3760/80 shrinks window 1828242657:1828242673. Repaired.
TCP: Treason uncloaked! Peer 210.76.114.42:2544/80 shrinks window 504374393:504375853. Repaired.
..........
查了资料,求助了google:
That comes from the kernel tcp code below. Looks like the DLink has returned information yielding a transmit window smaller than it previously did; specifically it returned a window of zero plus an ack of up to byte 3957222360, thus indicating that it can accept nothing after that byte. Previously it had sent ome ack+wnd values indicating that it would accept up to byte 3957222379.
The Linux side is now supposed to send a packet every now and then forever until the returned window is nonzero. It does.
However, the dlink is apparently not responding in a timely manner. Any response would either open the window or update the rcv timestamp such that the thing will retransmit forever. It may be responding very slowly, or just not responding at all.
The kernel prints the message after it expected but did not see a response to the probe packet it sent to check for a nonzero window. The kernel implements exponential backoff retransmissions until it hasn't seen any response in 2m, then it will bail and close the connection. This is reasonable. It's unclear from your report if the connections are failing outright or just sometimes having to retransmit a probe against a peer that shrank the window.
结论:
The remote host decided to shrink the TCP window size without negotiating such with your Linux box. The message is of the informational level, meaning Linux doesn't like what it is seeing but will cope with it and carr
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