Documentation: ip-sysctl.txt: Document tcp_fastopen_key

Add docs for /proc/sys/net/ipv4/tcp_fastopen_key

Signed-off-by: Jason Baron <jbaron@akamai.com>
Signed-off-by: Christoph Paasch <cpaasch@apple.com>
Cc: Jeremy Sowden <jeremy@azazel.net>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jason Baron 2019-05-29 12:34:00 -04:00 committed by David S. Miller
parent aa1236cdfa
commit 2dc7e48dee

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@ -648,6 +648,26 @@ tcp_fastopen_blackhole_timeout_sec - INTEGER
0 to disable the blackhole detection.
By default, it is set to 1hr.
tcp_fastopen_key - list of comma separated 32-digit hexadecimal INTEGERs
The list consists of a primary key and an optional backup key. The
primary key is used for both creating and validating cookies, while the
optional backup key is only used for validating cookies. The purpose of
the backup key is to maximize TFO validation when keys are rotated.
A randomly chosen primary key may be configured by the kernel if
the tcp_fastopen sysctl is set to 0x400 (see above), or if the
TCP_FASTOPEN setsockopt() optname is set and a key has not been
previously configured via sysctl. If keys are configured via
setsockopt() by using the TCP_FASTOPEN_KEY optname, then those
per-socket keys will be used instead of any keys that are specified via
sysctl.
A key is specified as 4 8-digit hexadecimal integers which are separated
by a '-' as: xxxxxxxx-xxxxxxxx-xxxxxxxx-xxxxxxxx. Leading zeros may be
omitted. A primary and a backup key may be specified by separating them
by a comma. If only one key is specified, it becomes the primary key and
any previously configured backup keys are removed.
tcp_syn_retries - INTEGER
Number of times initial SYNs for an active TCP connection attempt
will be retransmitted. Should not be higher than 127. Default value