23 struct ip {  struct
25 	u_char	ip_hl:4,		/* header length */  argument
26 		ip_v:4;			/* version */  argument
29 	u_char	ip_v:4,			/* version */  argument
30 		ip_hl:4;		/* header length */  argument
32 	u_char	ip_tos;			/* type of service */  argument
33 	short	ip_len;			/* total length */  argument
34 	u_short	ip_id;			/* identification */  argument
35 	short	ip_off;			/* fragment offset field */  argument
39 	u_char	ip_ttl;			/* time to live */  argument
40 	u_char	ip_p;			/* protocol */  argument
41 	u_short	ip_sum;			/* checksum */  argument
42 	struct	in_addr ip_src,ip_dst;	/* source and dest address */  argument