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IPV6_V6ONLY(2const) — Linux manual page

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | ERRORS | HISTORY | SEE ALSO | COLOPHON 

IPV6_V6ONLY(2const)                                   IPV6_V6ONLY(2const)

NAME         top

       IPV6_V6ONLY - restrict to IPv6 only

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_IP, IPV6_V6ONLY,
                      const int *enable, sizeof(int));

DESCRIPTION         top

       If this flag is set to true (nonzero), then the socket is
       restricted to sending and receiving IPv6 packets only.  In this
       case, an IPv4 and an IPv6 application can bind to a single port at
       the same time.

       If this flag is set to false (zero), then the socket can be used
       to send and receive packets to and from an IPv6 address or an
       IPv4-mapped IPv6 address.

       The default value for this flag is defined by the contents of the
       file /proc/sys/net/ipv6/bindv6only.  The default value for that
       file is 0 (false).

ERRORS         top

       See IPPROTO_IPV6(2const).  See setsockopt(2).  See ipv6(7).

HISTORY         top

       POSIX.1-2001, Linux 2.4.21, Linux 2.6.

SEE ALSO         top

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

COLOPHON         top

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Linux man-pages 6.18            2026-01-05            IPV6_V6ONLY(2const)

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

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