IP_MULTICAST_IF(2const) IP_MULTICAST_IF(2const)

IP_MULTICAST_IF - local device for a multicast socket

Standard C library (libc-lc)

#include <netinet/in.h>  /* Definition of IP* constants */
#include <sys/socket.h>
int setsockopt(int sockfd, IPPROTO_IP, IP_MULTICAST_IF,
               const void val[size], size_t size);
int getsockopt(int sockfd, IPPROTO_IP, IP_MULTICAST_IF,
               struct in_addr *val, sizeof(struct in_addr));

Set the local device for a multicast socket.

The argument for setsockopt(2) is an ip_mreqn(2type) or (since Linux 3.5) ip_mreq(2type) structure, or an in_addr(2type) structure. (The kernel determines which structure is being passed based on the size passed in size.)

See IPPROTO_IP(2const). See setsockopt(2). See ip(7).

Linux 1.2.

IPPROTO_IP(2const), in_addr(2type), ip_mreqn(2type), setsockopt(2), ip(7)

2025-11-25 Linux man-pages 6.17