IP_FREEBIND(2const)                                        IP_FREEBIND(2const)

NAME
       IP_FREEBIND - bind to a nonlocal or nonexistent IP address

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

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

STANDARDS
       Linux.

HISTORY
       Linux 2.4.

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

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