EF_TCP_SYN_OPTS

Name

syn_opts

Default

7

Scope

per-stack

A bitmask specifying the TCP options to advertise in SYN segments:

• bit 0 (0x1) is set to 1 to enable PAWS and RTTM timestamps (RFC1323)
• bit 1 (0x2) is set to 1 to enable window scaling (RFC1323)
• bit 2 (0x4) is set to 1 to enable SACK (RFC2018)
• bit 3 (0x8) is set to 1 to enable ECN (RFC3128).

The values from /proc/sys/net/ipv4/tcp_sack, /proc/sys/net/ipv4/tcp_timestamp and /proc/sys/net/ipv4/tcp_window_scaling are used to find the default.