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From 14336b7b4c70b3def333ae78e654e8919107176b Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Nikola=20Forr=C3=B3?= <nforro@redhat.com>
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Date: Tue, 28 Jun 2016 13:50:57 +0200
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Subject: [PATCH 13/17] tcp.7: document TCP_USER_TIMEOUT
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---
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man-pages/man7/tcp.7 | 48 +++++++++++++++++++++++++++++++++++++++++++++---
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1 file changed, 45 insertions(+), 3 deletions(-)
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diff --git a/man-pages/man7/tcp.7 b/man-pages/man7/tcp.7
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index 93b4148..98ccf27 100644
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--- a/man-pages/man7/tcp.7
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+++ b/man-pages/man7/tcp.7
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@@ -46,9 +46,6 @@
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.\" TCP_THIN_DUPACK (2..6.34)
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.\" commit 7e38017557bc0b87434d184f8804cadb102bb903
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.\" Author: Andreas Petlund <apetlund@simula.no>
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-.\" TCP_USER_TIMEOUT (new in 2.6.37)
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-.\" Author: Jerry Chu <hkchu@google.com>
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-.\" commit dca43c75e7e545694a9dd6288553f55c53e2a3a3
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.\" TCP_REPAIR (3.5)
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.\" commit ee9952831cfd0bbe834f4a26489d7dce74582e37
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.\" Author: Pavel Emelyanov <xemul@parallels.com>
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@@ -1038,6 +1035,51 @@ aborting the attempt to connect.
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It cannot exceed 255.
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This option should not be used in code intended to be portable.
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.TP
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+.BR TCP_USER_TIMEOUT " (since Linux 2.6.37)"
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+.\" commit dca43c75e7e545694a9dd6288553f55c53e2a3a3
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+.\" Author: Jerry Chu <hkchu@google.com>
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+.\" The following text taken nearly verbatim from Jerry Chu's (excellent)
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+.\" commit message.
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+.\"
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+This option takes an
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+.IR "unsigned int"
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+as an argument.
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+When the value is greater than 0,
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+it specifies the maximum amount of time in milliseconds that transmitted
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+data may remain unacknowledged before TCP will forcibly close the
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+corresponding connection and return
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+.B ETIMEDOUT
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+to the application.
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+If the option value is specified as 0,
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+TCP will to use the system default.
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+
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+Increasing user timeouts allows a TCP connection to survive extended
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+periods without end-to-end connectivity.
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+Decreasing user timeouts
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+allows applications to "fail fast", if so desired.
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+Otherwise, failure may take up to 20 minutes with
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+the current system defaults in a normal WAN environment.
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+
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+This option can be set during any state of a TCP connection,
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+but is effective only during the synchronized states of a connection
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+(ESTABLISHED, FIN-WAIT-1, FIN-WAIT-2, CLOSE-WAIT, CLOSING, and LAST-ACK).
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+Moreover, when used with the TCP keepalive
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+.RB ( SO_KEEPALIVE )
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+option,
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+.B TCP_USER_TIMEOUT
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+will override keepalive to determine when to close a
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+connection due to keepalive failure.
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+
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+The option has no effect on when TCP retransmits a packet,
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+nor when a keepalive probe is sent.
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+
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+This option, like many others, will be inherited by the socket returned by
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+.BR accept (2),
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+if it was set on the listening socket.
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+
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+Further details on the user timeout feature can be found in
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+RFC\ 793 and RFC\ 5482 ("TCP User Timeout Option").
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+.TP
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.BR TCP_WINDOW_CLAMP " (since Linux 2.4)"
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.\" Precisely: since 2.3.41
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Bound the size of the advertised window to this value.
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--
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2.7.4
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