IP_ADD_MEMBERSHIP(2const)                            IP_ADD_MEMBERSHIP(2const)

NAME
       IP_ADD_MEMBERSHIP - join a multicast group

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_ADD_MEMBERSHIP,
                      const struct ip_mreqn *val, sizeof(struct ip_mreqn));

DESCRIPTION
       Join a multicast group.

       IP_ADD_MEMBERSHIP is valid only for setsockopt(2).

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

       EINVAL val->imr_multiaddr is not a valid multicast address.

HISTORY
       Linux 1.2.

       For compatibility, the old ip_mreq structure is still supported.  The
       kernel determines which structure is being passed based on the size
       passed in the last argument.

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

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