TCP-Level Socket Options
Level	Option	Description	*	R	W	Value	Type
SOL_TCP	TCP_KEEPALIVE	Keep alive delay (replaced with sysctl call)	N	-	-	Integer	int
SOL_TCP	TCP_MAXRT	Maximum Retransmit Time	N	-	-	Integer	int
SOL_TCP	TCP_MAXSEG	Set Max Segment (Transmission Buffer) Size	Y	Y	Y	Integer	int
SOL_TCP	TCP_NODELAY	Enable Nagle Algorithm	Y	Y	Y	Boolean	int
SOL_TCP	TCP_STDURG	Specifies location of urgent byte (replaced with sysctl call)	N	-	-	Boolean	int
SOL_TCP	TCP_CORK	Never send partially complete segments	Y	Y	Y	Boolean	int
SOL_TCP	TCP_KEEPIDLE	Start keeplives after this period	2.4	Y	Y	Integer	int
SOL_TCP	TCP_KEEPINTVL	Interval between keepalives	2.4	Y	Y	Integer	int
SOL_TCP	TCP_KEEPCNT	Number of keepalives before death	2.4	Y	Y	Integer	int
SOL_TCP	TCP_SYNCNT	Number of SYN retransmits	2.4	Y	Y	Integer	int
SOL_TCP	TCP_LINGER2	Life time of orphaned FIN-WAIT-2 state	2.4	Y	Y	Integer	int
SOL_TCP	TCP_DEFER_ACCEPT	Wake up listener only when data arrive	2.4	Y	Y	Integer	int
SOL_TCP	TCP_WINDOW_CLAMP	Bound advertised window	2.4	Y	Y	Integer	int
SOL_TCP	TCP_INFO	Get information and stats about this connection	2.4	Y	N	TCP Info	struct tcp_info