.\" Copyright, the authors of the Linux man-pages project
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.TH IP_TRANSPARENT 2const 2025-11-25 "Linux man-pages 6.17"
.SH NAME
IP_TRANSPARENT
\-
transparent proxying
.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_TRANSPARENT,
.BI "               const\~int\~*" enable ,\~sizeof(int));
.fi
.SH DESCRIPTION
Setting this boolean option enables transparent proxying on this socket.
.P
This socket option allows
the calling application to bind to a nonlocal IP address and operate
both as a client and a server with the foreign address as the local endpoint.
.P
This requires that routing be set up in a way that
packets going to the foreign address are routed through the TProxy box
(i.e., the system hosting the application that employs the
.B IP_TRANSPARENT
socket option).
.P
Enabling this socket option requires superuser privileges
(the
.B CAP_NET_ADMIN
or
.B CAP_NET_RAW
capability).
.P
TProxy redirection with the iptables TPROXY target also requires that
this option be set on the redirected socket.
.SH ERRORS
See
.BR IPPROTO_IP (2const).
See
.BR setsockopt (2).
See
.BR ip (7).
.SH STANDARDS
Linux.
.SH HISTORY
Linux 2.6.24.
.\" commit f5715aea4564f233767ea1d944b2637a5fd7cd2e
.\"     This patch introduces the IP_TRANSPARENT socket option: enabling that
.\"     will make the IPv4 routing omit the non-local source address check on
.\"     output.  Setting IP_TRANSPARENT requires NET_ADMIN capability.
.\" http://lwn.net/Articles/252545/
.SH SEE ALSO
.BR IPPROTO_IP (2const),
.BR setsockopt (2),
.BR ip (7)