IPV6_ADDRFORM(2const) — Linux manual page

IPV6_ADDRFORM(2const)                               IPV6_ADDRFORM(2const)

NAME         top

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

LIBRARY         top

       Standard C library (libc, -lc)

SYNOPSIS         top

       #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         top

       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         top

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

SEE ALSO         top

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

COLOPHON         top

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Linux man-pages 6.18            2025-12-02          IPV6_ADDRFORM(2const)

Pages that refer to this page: IPPROTO_IPV6(2const)

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