diff options
| author | Michael Tuexen <tuexen@FreeBSD.org> | 2021-06-11 18:14:34 +0000 |
|---|---|---|
| committer | Michael Tuexen <tuexen@FreeBSD.org> | 2021-07-13 18:24:09 +0000 |
| commit | c5ba872129b3afee95953294fbe55e014559d408 (patch) | |
| tree | 1cb8c0cbc935d1fe8d2c263c77a6fdd60c56e59d | |
| parent | 67d02e13011fa80786a243c9464cea248de4c127 (diff) | |
tcp: tolerate missing timestamps
Some TCP stacks negotiate TS support, but do not send TS at all
or not for keep-alive segments. Since this includes modern widely
deployed stacks, tolerate the violation of RFC 7323 per default.
Reviewed by: rgrimes, rrs, rscheff
Differential Revision: https://reviews.freebsd.org/D30740
Sponsored by: Netflix, Inc.
(cherry picked from commit 870af3f4dc57a6bbfc03f6a49ca0d5b7ff1b975a)
| -rw-r--r-- | share/man/man4/tcp.4 | 6 | ||||
| -rw-r--r-- | sys/netinet/tcp_subr.c | 9 |
2 files changed, 12 insertions, 3 deletions
diff --git a/share/man/man4/tcp.4 b/share/man/man4/tcp.4 index 0b59e2ec801d..86c289c5bec5 100644 --- a/share/man/man4/tcp.4 +++ b/share/man/man4/tcp.4 @@ -34,7 +34,7 @@ .\" From: @(#)tcp.4 8.1 (Berkeley) 6/5/93 .\" $FreeBSD$ .\" -.Dd April 24, 2021 +.Dd June 27, 2021 .Dt TCP 4 .Os .Sh NAME @@ -382,7 +382,9 @@ segments belonging to connections for which support of .Tn TCP timestamps has been negotiated. -(default is 0, i.e., the missing of timestamps is not tolerated). +As of June 2021, several TCP stacks are known to violate RFC 7323, including +modern widely deployed ones. +Therefore the default is 1, i.e., the missing of timestamps is tolerated. .It Dv TCPCTL_MSSDFLT .Pq Va mssdflt The default value used for the maximum segment size diff --git a/sys/netinet/tcp_subr.c b/sys/netinet/tcp_subr.c index 32a814ac2c4e..c3afb3a1567a 100644 --- a/sys/netinet/tcp_subr.c +++ b/sys/netinet/tcp_subr.c @@ -268,7 +268,14 @@ SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(tcp_do_rfc1323), 0, "Enable rfc1323 (high performance TCP) extensions"); -VNET_DEFINE(int, tcp_tolerate_missing_ts) = 0; +/* + * As of June 2021, several TCP stacks violate RFC 7323 from September 2014. + * Some stacks negotiate TS, but never send them after connection setup. Some + * stacks negotiate TS, but don't send them when sending keep-alive segments. + * These include modern widely deployed TCP stacks. + * Therefore tolerating violations for now... + */ +VNET_DEFINE(int, tcp_tolerate_missing_ts) = 1; SYSCTL_INT(_net_inet_tcp, OID_AUTO, tolerate_missing_ts, CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(tcp_tolerate_missing_ts), 0, "Tolerate missing TCP timestamps"); |