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Update a comment to reflect the current reality.

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SYN-cache entries live for abaut 12 seconds, not 45, when default
setting are used.

MFC after:		1 week
Sponsored by:		Netflix, Inc.
This commit is contained in:
Michael Tuexen 2019-01-24 16:40:14 +00:00
parent d81ca439e7
commit 34bb795ba1
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=343401
1 changed files with 6 additions and 1 deletions
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7
sys/netinet/tcp_syncache.c
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@ -154,7 +154,12 @@ static int syncookie_cmp(struct in_conninfo *inc, struct syncache_head *sch,
/*
* Transmit the SYN,ACK fewer times than TCP_MAXRXTSHIFT specifies.
* 3 retransmits corresponds to a timeout of 3 * (1 + 2 + 4 + 8) == 45 seconds,
* 3 retransmits corresponds to a timeout with default values of
* TCPTV_RTOBASE * ( 1 +
* tcp_syn_backoff[1] +
* tcp_syn_backoff[2] +
* tcp_syn_backoff[3]) + 3 * tcp_rexmit_slop,
* 3000 ms * (1 + 1 + 1 + 1) + 3 * 200 ms = 12300 ms,
* the odds are that the user has given up attempting to connect by then.
*/
#define SYNCACHE_MAXREXMTS 3