模拟TCP通信协议

1.定义IP头部格式

2.定义数据校验协议

    public struct IP_Head
    {
        public char headlength ;
        public char version;
        public char tos;

        public short total_len;
        public short identifier;
        public char ttl;
        public char protocal;
        public short checknum;
        public long sourceIP;
        public long destIP;

    }

    public struct ICMP_Header
    {
        byte type;
        byte code;
        short cknum;
        short id;
        short seq;
    }