IP_MSFILTER(2const)                                        IP_MSFILTER(2const)

NAME
       IP_MSFILTER - multicast source filtering

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_MSFILTER,
                      const struct ip_msfilter *val,
                      sizeof(struct ip_msfilter));

       struct ip_msfilter {
           struct in_addr  imsf_multiaddr;  // IP multicast group address
           struct in_addr  imsf_interface;  // IP address of local interface
           uint32_t        imsf_fmode;      // Filter-mode

           uint32_t        imsf_numsrc;     // Number of elements in .imsf_slist
           struct in_addr  imsf_slist[1];   // Array of source addresses
       };

DESCRIPTION
       This option provides access to the advanced full-state filtering API.

       There are two macros, MCAST_INCLUDE and MCAST_EXCLUDE, which can be
       used to specify the filtering mode.

       Additionally, the IP_MSFILTER_SIZE(n) macro exists to determine how
       much memory is needed to store ip_msfilter structure with n sources in
       the source list.

       For the full description of multicast source filtering refer to RFC
       3376.

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

STANDARDS
       Linux.

HISTORY
       Linux 2.4.22, Linux 2.5.68.

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

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