如前所述,正确的做法是使用struct ifreq
指定接口名称。这是我的代码示例。
#define SERVERPORT 5555
...
struct ifreq ifr;
/* Create the socket */
sd = socket(AF_INET, SOCK_STREAM, 0);
if (sd < 0)
{
printf("Error in socket() creation - %s", strerror(errno));
}
/* Bind to eth1 interface only - this is a private VLAN */
memset(&ifr, 0, sizeof(ifr));
snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), "eth1");
if ((rc = setsockopt(sd, SOL_SOCKET, SO_BINDTODEVICE, (void *)&ifr, sizeof(ifr))) < 0)
{
perror("Server-setsockopt() error for SO_BINDTODEVICE");
printf("%s\n", strerror(errno));
close(sd);
exit(-1);
}
/* bind to an address */
memset(&serveraddr, 0x00, sizeof(struct sockaddr_in));
serveraddr.sin_family = AF_INET;
serveraddr.sin_port = htons(SERVERPORT);
serveraddr.sin_addr.s_addr = inet_addr("9.1.2.3");
int rc = bind(sd, (struct sockaddr *)&serveraddr, sizeof(serveraddr));
我还想从安全角度补充一点,虽然将套接字绑定到接口很好,但INADDR_ANY
用作侦听 IP 地址没有意义。这样做会使端口在所有网络接口上的 netstat 中显示为打开。
Proto Recv-Q Send-Q Local Address Foreign Address State User Inode PID/Program name
tcp 0 0 0.0.0.0:5555 0.0.0.0:* LISTEN 0 210898 26996/myserver
相反,我指定了一个特定于正在使用的接口(私有 VLAN)的 IP 地址。这也修复了 netstat 输出:
Proto Recv-Q Send-Q Local Address Foreign Address State User Inode PID/Program name
tcp 0 0 9.1.2.3:5555 0.0.0.0:* LISTEN 0 210898 26996/myserver