Socket Options (get/setsockopt())

Tables A.4 through A.7 list the various socket options and the required parameters. Not all options are size compatible between UNIX types. For example, IP_TTL in Linux allows a type int, but only fills the first byte. IBM's AIX restricts the same option to a char instead.

Table A.4. General Socket Options

Level	Option	Description	*	R	W	Value	Type
SOL_SOCKET	SO_ATTACH_FILTER	Attach filter	?	?	?	Integer	int
SOL_SOCKET	SO_BINDTODEVICE	Bind to device	?	?	?	String	char*
SOL_SOCKET	SO_BROADCAST	Enable broadcast	Y	Y	Y	Boolean	int
SOL_SOCKET	SO_BSDCOMPAT	Request BSD bug-for-bug compatibility	Y	Y	Y	Boolean	int
SOL_SOCKET	SO_DEBUG	Enable socket debugging	Y	Y	Y	Boolean	int
SOL_SOCKET	SO_DETACH_FILTER	Detach filter	?	?	?	Integer	int
SOL_SOCKET	SO_DONTROUTE	Forbid routing	Y	Y	Y	Boolean	int
SOL_SOCKET	SO_ERROR	Last error	Y	Y	Y	Integer	int
SOL_SOCKET	SO_KEEPALIVE	Enable keeping connection alive	Y	Y	Y	Boolean	int
SOL_SOCKET	SO_LINGER	Linger until data sent	Y	Y	Y	Linger	struct linger
SOL_SOCKET	SO_NO_CHECK	No checking	Y	Y	Y	Boolean	int
SOL_SOCKET	SO_OOBINLINE	Place out-of-band inline	Y	Y	Y	Boolean	int
SOL_SOCKET	SO_PASSCRED	Enable passing user credentials	Y	Y	Y	Boolean	int
SOL_SOCKET	SO_PEERCRED	Peer Credentials	Y	Y	Y	Credentials	struct ucred
SOL_SOCKET	SO_PRIORITY	Set the queue priority	Y	Y	Y	Integer	int
SOL_SOCKET	SO_RCVBUF	Receive buffer size	Y	Y	Y	Integer	int
SOL_SOCKET	SO_RCVLOWAT	Receive low water mark	Y	Y	N	Integer	int
SOL_SOCKET	SO_RCVTIMEO	Receive Timeout	Y	Y	Y	Time	struct timeval
SOL_SOCKET	SO_REUSEADDR	Reuse Address	Y	Y	Y	Boolean	int
SOL_SOCKET	SO_REUSEPORT	Reuse Address(multicasting)	N	-	-	Boolean	int
SOL_SOCKET	SO_SECURITY_ AUTHENTICATION	Security authentication	N	-	-	Integer	int
SOL_SOCKET	SO_SECURITY_ ENCRYPTION_ NETWORK	Security encryption network	N	-	-	Integer	int
SOL_SOCKET	SO_SECURITY_ ENCRYPTION_ TRANSPORT	Security encryption transport	N	-	-	Integer	int
SOL_SOCKET	SO_SNDBUF	Send buffer size	Y	Y	Y	Integer	int
SOL_SOCKET	SO_SNDLOWAT	Send low water mark	Y	Y	Y	Integer	int
SOL_SOCKET	SO_SNDTIMEO	Send Timeout	Y	Y	Y	Time	struct timeval
SOL_SOCKET	SO_TYPE	Socket Type	Y	Y	Y	Integer	int