struct iphdr--IP头结构体
IP首部在Linux内核中的结构体struct iphdr {#if defined(__LITTLE_ENDIAN_BITFIELD) __u8 ihl:4, version:4;#elif defined (__BIG_ENDIAN_BITFIELD) __u8 version:4, ihl:4;#else#error "Please fix <asm/byteorder.h>"#endif __u8 tos; __be16 tot_l
