TCP_SACK is not a kernel option any more: https://github.com/openbsd/src/commit/48ef9290235556f3a8883a80191c0cdca60ca4c1
diff --git a/share/man/man4/tcp.4 b/share/man/man4/tcp.4 index 6fe07e310d7..1e4a34e0a68 100644 --- a/share/man/man4/tcp.4 +++ b/share/man/man4/tcp.4 @@ -159,8 +159,6 @@ Set the maximum segment size for this connection. The maximum segment size can only be lowered. .It Cd TCP_SACK_ENABLE Use selective acknowledgements for this connection. -See -.Xr options 4 . .It Cd TCP_MD5SIG Use TCP MD5 signatures per RFC 2385. This requires
