.\" Copyright, the authors of the Linux man-pages project
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.TH IP_FREEBIND 2const (date) "Linux man-pages (unreleased)"
.SH NAME
IP_FREEBIND
\-
bind to a nonlocal or nonexistent IP address
.SH LIBRARY
Standard C library
.RI ( libc ,\~ \-lc )
.SH SYNOPSIS
.nf
.BR "#include <netinet/in.h>" "  /* Definition of " IP* " constants */"
.B #include <sys/socket.h>
.P
.BI int\~setsockopt(int\~ sockfd ,\~IPPROTO_IP,\~IP_FREEBIND,
.BI "               const\~int\~*" enable ,\~sizeof(int));
.fi
.SH DESCRIPTION
If enabled,
this boolean option allows binding to an IP address
that is nonlocal or does not (yet) exist.
.P
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.
.P
This option is the per-socket equivalent of the
.I /proc/sys/net/ipv4/ip_nonlocal_bind
interface.
.SH ERRORS
See
.BR IPPROTO_IP (2const).
See
.BR setsockopt (2).
See
.BR ip (7).
.SH STANDARDS
Linux.
.SH HISTORY
Linux 2.4.
.\" Precisely: since Linux 2.4.0-test10
.SH SEE ALSO
.BR IPPROTO_IP (2const),
.BR setsockopt (2),
.BR proc_sys_net_ipv4 (5),
.BR ip (7)