Option to use with setsockopt at the IPPROTO_IP level

/*   Option   to   use   with   setsockopt   at   the   IPPROTO_IP   level   */  

#define IP_OPTIONS 1   /*   set/get   IP   options   */  
#define IP_HDRINCL 2   /*   header   is   included   with   data   */  
#define IP_TOS 3   /*   IP   type   of   service   and   preced*/  
#define IP_TTL 4   /*   IP   time   to   live   */  
#define IP_MULTICAST_IF 9   /*   set/get   IP   multicast   i/f     */  
#define IP_MULTICAST_TTL               10   /*   set/get   IP   multicast   ttl   */ 
#define IP_MULTICAST_LOOP 11 /*set/get IP multicast loopback */ 
#define IP_ADD_MEMBERSHIP             12   /*   add   an   IP   group   membership   */ 
#define IP_DROP_MEMBERSHIP           13/*   drop   an   IP   group   membership   */ 
#define   IP_DONTFRAGMENT           14   /*   don 't   fragment   IP   datagrams   */