diff options
Diffstat (limited to 'share/man/man4/tcp.4')
| -rw-r--r-- | share/man/man4/tcp.4 | 24 |
1 files changed, 9 insertions, 15 deletions
diff --git a/share/man/man4/tcp.4 b/share/man/man4/tcp.4 index 9911a36..8c71716 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 October 21, 2016 +.Dd February 6, 2017 .Dt TCP 4 .Os .Sh NAME @@ -272,33 +272,27 @@ or the internal send buffer is filled. This option enables the use of MD5 digests (also known as TCP-MD5) on writes to the specified socket. Outgoing traffic is digested; -digests on incoming traffic are verified if the -.Va net.inet.tcp.signature_verify_input -sysctl is nonzero. -The current default behavior for the system is to respond to a system -advertising this option with TCP-MD5; this may change. +digests on incoming traffic are verified. +When this option is enabled on a socket, all inbound and outgoing +TCP segments must be signed with MD5 digests. .Pp One common use for this in a .Fx router deployment is to enable based routers to interwork with Cisco equipment at peering points. Support for this feature conforms to RFC 2385. -Only IPv4 -.Pq Dv AF_INET -sessions are supported. .Pp In order for this option to function correctly, it is necessary for the administrator to add a tcp-md5 key entry to the system's security associations database (SADB) using the .Xr setkey 8 utility. -This entry must have an SPI of 0x1000 and can therefore only be specified -on a per-host basis at this time. +This entry can only be specified on a per-host basis at this time. .Pp -If an SADB entry cannot be found for the destination, the outgoing traffic -will have an invalid digest option prepended, and the following error message -will be visible on the system console: -.Em "tcp_signature_compute: SADB lookup failed for %d.%d.%d.%d" . +If an SADB entry cannot be found for the destination, +the system does not send any outgoing segments and drops any inbound segments. +.Pp +Each dropped segment is taken into account in the TCP protocol statistics. .El .Pp The option level for the |
