IPV6_ADDRFORM(2const)                                    IPV6_ADDRFORM(2const)

NAME
       IPV6_ADDRFORM - turn an AF_INET6 socket into a socket of a different
       address family

LIBRARY
       Standard C library (libc, -lc)

SYNOPSIS
       #include <netinet/in.h>  /* Definition of IP* constants */
       #include <sys/socket.h>

       int setsockopt(int sockfd, IPPROTO_IPV6, IPV6_ADDRFORM,
                      &(const int){AF_INET}, sizeof(int));

DESCRIPTION
       Turn an AF_INET6 socket into a socket of a different address family.

       Only AF_INET is currently supported for that.

       It is allowed only for IPv6 sockets that are connected and bound to a
       v4-mapped-on-v6 address.

       This is useful to pass v4-mapped sockets as file descriptors to
       programs that don't know how to deal with the IPv6 API.

ERRORS
       See setsockopt(2).  See ipv6(7).

SEE ALSO
       IPPROTO_IPV6(2const), setsockopt(2), ipv6(7)

Linux man-pages 6.17              2025-12-02             IPV6_ADDRFORM(2const)