IP_MULTICAST_IF(2const)                                IP_MULTICAST_IF(2const)

NAME
       IP_MULTICAST_IF - local device for a multicast socket

LIBRARY
       Standard C library (libc, -lc)

SYNOPSIS
       #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));

DESCRIPTION
       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.)

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

HISTORY
       Linux 1.2.

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

Linux man-pages 6.17              2025-11-25           IP_MULTICAST_IF(2const)