IP_FREEBIND(2const) — Linux manual page

IP_FREEBIND(2const)                                   IP_FREEBIND(2const)

NAME         top

       IP_FREEBIND - bind to a nonlocal or nonexistent IP address

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, IP_FREEBIND,
                      const int *enable, sizeof(int));

DESCRIPTION         top

       If enabled, this boolean option allows binding to an IP address
       that is nonlocal or does not (yet) exist.

       This permits listening on a socket, without requiring the
       underlying network interface or the specified dynamic IP address
       to be up at the time that the application is trying to bind to it.

       This option is the per-socket equivalent of the
       /proc/sys/net/ipv4/ip_nonlocal_bind interface.

ERRORS         top

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

STANDARDS         top

       Linux.

HISTORY         top

       Linux 2.4.

SEE ALSO         top

       IPPROTO_IP(2const), setsockopt(2), proc_sys_net_ipv4(5), ip(7)

COLOPHON         top

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Linux man-pages 6.18            2025-11-25            IP_FREEBIND(2const)

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

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