＃router add –net 224.0.0.0 netmask 224.0.0.0 dev lo

＃route –eKernel IP routing table
Destination     gatewary   Genmask       Flags  MSS  Window irtt Iface
10.0.0.0        *         255.255.255.0  U     0     0      0   eth0
127.0.0.0       *         255.0.0.0      U     0     0      0    lo
BASE_ADDRESS>MC *         240.0.0.0      U     0     0      0     lo
Default         10.0.0.1   0.0.0.0       UG    0     0      0     eth0

/* 
 * broadcast.c - An IP multicast server 
 */
#include 
#include 
#include 
#include 
#include #include 
#include int port = 6789;
int main(void)
{    
int socket_descriptor;  
 struct sockaddr_in address;  
  /*  首先建立套接口 */
    socket_descriptor = socket(AF_INET, SOCK_DGRAM, 0);  
  if (socket_descriptor == -1) 
{      
  perror(\"Opening socket\"); 
       exit(EXIT_FAILURE);  
  }   
 /* 初始化IP多播地址 */ 
 memset(&address, 0, sizeof(address));   
 address.sin_family = AF_INET;  
 address.sin_addr.s_addr = inet_addr(\"224.0.0.1\"); 
 address.sin_port = htons(port);  
  /* 开始进行IP多播 */  
while(1) { 
 if(sendto(socket_descriptor, \"test from broadcast\", 
 sizeof(\"test from broadcast\"), 0,   
 (struct sockaddr *)&address, sizeof(address)) < 0) 
{  
 perror(\"sendto\");  
 exit(EXIT_FAILURE); 
 }   
 sleep(2);  
}  
exit(EXIT_SUCCESS);}

/* 
 * listen.c - An IP multicast client */
#include 
#include 
#include 
#include 
#include 
#include 
#include 
char * host_name = \"224.0.0.1\";
 /* 多播IP地址 */
int port = 6789;
int main(void)
{ 
   struct ip_mreq command; 
   int loop = 1;
 /* 多播循环 */ 
  int iter = 0;
  int sin_len;
  char message[256];
  int socket_descriptor;
 struct sockaddr_in sin;
 struct hostent *server_host_name;
 if((server_host_name = gethostbyname(host_name)) == 0)
 {
   perror(\"gethostbyname\");
   exit(EXIT_FAILURE);
    }   
 /*bzero(&sin, sizeof(sin));*/
memset(&sin, 0, sizeof(sin));
  sin.sin_family = AF_INET;
  sin.sin_addr.s_addr = htonl(INADDR_ANY);
  sin.sin_port = htons(port);
  if((socket_descriptor = socket(PF_INET, SOCK_DGRAM, 0)) == -1) 
{ perror(\"socket\");
 exit(EXIT_FAILURE);
 }
 /* 调用bind之前，设置套接口选项启用多播IP支持*/
 loop = 1;
 if(setsockopt(socket_descriptor, 
SOL_SOCKET, SO_REUSEADDR,
 &loop, sizeof(loop)) < 0)
{ 
 perror(\"setsockopt:SO_REUSEADDR\");
 exit(EXIT_FAILURE);
  }
if(bind(socket_descriptor, 
(struct sockaddr *)&sin, sizeof(sin)) < 0)
 {
   perror(\"bind\"); 
   exit(EXIT_FAILURE);
    }
/* 在同一个主机上进行广播设置套接口，
作用是方便单个开发系统上测试多播IP广播 */ 
loop = 1; 
if(setsockopt(socket_descriptor, 
IPPROTO_IP, IP_MULTICAST_LOOP, 
  &loop, sizeof(loop)) < 0) 
{   
 perror(\"setsockopt:IP_MULTICAST_LOOP\");
 exit(EXIT_FAILURE); 
   } 
 /* 加入一个广播组。进一步告诉Linux内核，
特定的套接口即将接受广播数据*/ 
 command.imr_multiaddr.s_addr = inet_addr(\"224.0.0.1\"); 
 command.imr_interface.s_addr = htonl(INADDR_ANY);
 if(command.imr_multiaddr.s_addr == -1) 
{  
 perror(\"224.0.0.1 not a legal multicast address\"); 
 exit(EXIT_FAILURE); 
}
if (setsockopt(socket_descriptor, IPPROTO_IP, IP_ADD_MEMBERSHIP, 
  &command, sizeof(command)) < 0)
 {   
  perror(\"setsockopt:IP_ADD_MEMBERSHIP\");
    } 
 while(iter++ < 8) 
{    
  sin_len = sizeof(sin); 
  if(recvfrom(socket_descriptor, message, 256, 0,
  (struct sockaddr *)&sin, &sin_len) == -1) { 
   perror(\"recvfrom\");   
    }  
printf(\"Response #%-2d from server: %s\\n\", iter, message);
     sleep(2);    } 
   /* 接受8个广播后退出 */ 
if(setsockopt(socket_descriptor, IPPROTO_IP, IP_DROP_MEMBERSHIP,
     &command, sizeof(command)) < 0) { 
     perror(\"setsockopt:IP_DROP_MEMBERSHIP\"); 
   }   
close(socket_descriptor); 
exit(EXIT_SUCCESS);}