IP-Level Socket Options
Level	Option	Description	*	R	W	Value	Type
SOL_IP	IP_ADD_MEMBERSHIP	Add Multicast Membership	Y	Y	Y	IPv4 Multicast Address	struct ip_mreq
SOL_IP	IP_DROP_MEMBERSHIP	Drop Multicast Membership	Y	Y	Y	IPv4 Multicast Address	struct ip_mreq
SOL_IP	IP_HDRINCL	Enable Manual IP Header Creation	Y	Y	Y	Boolean	int
SOL_IP	IP_MTU_DISCOVER	MTU Discover	Y	Y	Y	Integer	int
SOL_IP	IP_MULTICAST_IF	Outgoing Multicast Interface	Y	Y	Y	IPv4 Address	struct in_addr
SOL_IP	IP_MULTICAST_LOOP	Enable Multicast Loopback	Y	Y	Y	Boolean	int
SOL_IP	IP_MULTICAST_TTL	Multicast TTL	Y	Y	Y	Integer	int
SOL_IP	IP_OPTIONS	IP Options	Y	Y	Y	Options	int[ ]
SOL_IP	IP_PKTINFO	Enable Getting Packet Info	Y	Y	Y	Boolean	int
SOL_IP	IP_PKTOPTIONS	Packet Options	N	-	-	Options	int[ ]
SOL_IP	IP_RECVERR	Enable Receive Error Packets	Y	Y	Y	Boolean	int
SOL_IP	IP_RECVOPTS	Enable Receive Options	Y	Y	Y	Boolean	int
SOL_IP	IP_RECVTOS	Get Received TOS (?)	Y	Y	Y	Integer	int
SOL_IP	IP_RECVTTL	Get Received TTL (?)	Y	Y	Y	Integer	int
SOL_IP	IP_RETOPTS	RETOPTS ??	Y	Y	Y	Boolean	int
SOL_IP	IP_ROUTER_ALERT	Enable Router Alerts	N	-	-	Boolean	int
SOL_IP	IP_TOS	Type of Service (TOS)	Y	Y	Y	Integer	int
SOL_IP	IP_TTL	Time to Live (TTL)	Y	Y	Y	Integer	int