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.\" $OpenBSD: divert.4,v 1.1 2009/09/08 17:00:41 michele Exp $
.\"
.\" Copyright (c) 2009 Michele Marchetto <michele@openbsd.org>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.Dd $Mdocdate: September 8 2009 $
.Dt DIVERT 4
.Os
.Sh NAME
.Nm divert
.Nd Kernel packet diversion mechanism
.Sh SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <sys/socket.h>
.Fd #include <netinet/in.h>
.Ft int
.Fn socket AF_INET SOCK_RAW IPPROTO_DIVERT
.Sh DESCRIPTION
Divert sockets can be bound through
.Xr bind 2
to a divert port and they will receive every packet
diverted to that port by
.Xr pf 4 .
Consult
.Xr pf.conf 5
for the correct syntax.
Packets can also be reinjected into the divert socket, in which case they
re-enter kernel packet processing skipping
.Xr pf 4
filters, avoiding loops.
.Pp
Diverted packets can be read via
.Xr read 2 ,
.Xr recv 2 ,
or
.Xr recvfrom 2
from the divert socket.
.Xr pf 4
will reassemble the IP packets by default before sending them to the divert
socket.
In addition, TCP reassembling can be enabled on a per-rule basis, see
.Xr pf.conf 5
for details.
Writing to a divert socket can be achieved using
.Xr sendto 2
and it will skip
.Xr pf 4
filters to avoid loops.
.Pp
If
.Xr pf 4
diverts packets but there are no divert sockets listening,
the packets are dropped.
.Sh SEE ALSO
.Xr socket 2 ,
.Xr ip 4 ,
.Xr pf.conf 5 ,
.Sh HISTORY
The
.Nm
protocol first appeared in
.Ox 4.7.
|
