This set of tests focuses on the sending of SYN-segments moving the state of the TCP connection from CLOSED
to SYN-SENT
and possibly to CLOSED
again.
The list of socket options with level IPPROTO_TCP
affecting this behaviour is:
TCP_KEEPINIT
TCP_NOOPT
The list of sysctl
-variables affecting the sending of SYN-segments is
net.inet.tcp.keepinit
net.inet.tcp.rexmit_drop_options
net.inet.tcp.sack.enable
net.inet.tcp.rfc1323
kern.ipc.maxsockbuf
net.inet.tcp.ecn.enable
net.inet.tcp.ecn.maxretries
- The sysctl variable
net.inet.tcp.rexmit_drop_options
is not described in theTCP(4)
man page. The description of the sysctl variable (when displayed withsysctl -d net.inet.tcp.rexmit_drop_options
states that no options will be used from the third and later retransmits of the SYN-segment. However, the MSS option is not dropped. Either change the code or change the documentation and add an entry to the man page. - The MSS is based on an MTU of 1500 bytes instead of the configured one.