4 struct ip {                     /* ip leader */  struct
5 	u_char ip_hl:4,			/* header length */  argument
7 		ip_v:4;			/* version */  argument
8 	u_char ip_tos;			/* type of service */  argument
10 	u_short ip_len;			/* total length */  argument
11 	u_short ip_id;			/* identification */  argument
12 	u_short ip_off;			/* fragment offset field */  argument
16 	u_char ip_ttl;			/* time to live */  argument
17 	u_char ip_p;			/* protocol */  argument
18 	u_short ip_sum;			/* checksum */  argument
22 		struct ip *ip_nxt;      /* ->next fragment */        argument
28 		struct ip *ip_prv;      /* ->prev fragment */  argument
34 /* ip options */  argument