我有一个示例代码来接收RedHat Enterprise Linux5.5中的broatcast数据包,以下是关键来源:

struct ip_mreq {
    struct in_addr imr_multiaddr;    /* IP multicast address of group */
    struct in_addr imr_interface;    /* local IP address of interface */
} mreq; 

serv_addr.sin_addr.s_addr = inet_addr("225.0.100.100");
portno = 10000 ;
serv_addr.sin_port = htons(portno);
mreq.imr_multiaddr = serv_addr.sin_addr; 
mreq.imr_interface.s_addr = INADDR_ANY ;
//mreq.imr_interface.s_addr = inet_addr("192.168.165.212");
setsockopt(newsockfd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
setsockopt(newsockfd, SOL_SOCKET, SO_REUSEADDR, &set, sizeof(set));

路由表是:

[root @ linux01~] #route内核IP路由表目的网关Genmask Flags Metric参考使用Iface

192.172.165.0 * 255.255.255.0 U 0 0 0 eth0

128.110.10.0 * 255.255.255.0 U 0 0 0 eth2

225.0.0.0 192.172.165.212 255.255.0.0 UG 0 0 0 eth0

169.254.0.0 * 255.255.0.0 U 0 0 0 eth0

默认值128.110.10.254 0.0.0.0 UG 0 0 0 eth2

我使用tcpdump -i eth0 -nn观看加入广播组是否成功,

mreq.imr_interface.s_addr = INADDR_ANY ;
//mreq.imr_interface.s_addr = inet_addr("192.168.165.212");

将表明:

16:14:24.322672 IP 192.172.165.212> 225.0.100.100:igmp v2 report 225.0.100.100

mreq.imr_interface.s_addr = INADDR_ANY ;
//mreq.imr_interface.s_addr = inet_addr("192.168.165.212");

这将不会有igmp v2报告消息!!

我的问题是:为什么INADDR_ANY有效,但不是inet_addr(“192.168.165.212”);

我错过了什么?

eth0 inet addr:192.172.165.212 Bcast:192.172.165.255掩码:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500公制:1

eth2 inet addr:128.110.10.69 Bcast:128.110.10.255掩码:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500公制:1