.\" Copyright (c) 2005 Gleb Smirnoff <glebius@FreeBSD.org>
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.Dd May 6, 2005
.Dt NG_NAT 4
.Os
.Sh NAME
.Nm ng_nat
.Nd NAT netgraph node type
.Sh SYNOPSIS
.In netgraph/ng_nat.h
.Sh DESCRIPTION
An
.Nm
node performs network address translation (NAT) of packets
passing through it.
An
.Nm
node uses
.Xr libalias 3
engine for packet aliasing.
At this moment it supports the basic functionality of the library.
.Sh HOOKS
This node type has two hooks:
.Pp
.Bl -tag -width foobar
.It Dv out
Packets received on this hook are considered outgoing and would be
masqueraded to configured address.
.It Dv in
Packets coming on this hook are considered incoming and would be
dealiased.
.El
.Sh CONTROL MESSAGES
This node type supports the generic control messages, plus the following:
.Bl -tag -width foo
.It Dv NGM_NAT_SET_IPADDR Pq Li setaliasaddr
Configure aliasing address for node.
After both hooks are connected and aliasing address configured,
node is ready for aliasing operation.
.El
.Sh SHUTDOWN
This node shuts down upon receipt of a
.Dv NGM_SHUTDOWN
control message, or when both hooks are disconnected.
.Sh EXAMPLES
In the following example packets are injected into
.Nm
node with help of
.Xr ng_ipfw 4
node.
.Bd -literal -offset indent
# Create NAT node
ngctl mkpeer ipfw: nat 60 out
ngctl name ipfw:60 nat
ngctl connect ipfw: nat: 61 in
ngctl msg nat: setaliasaddr x.y.35.8

# Divert traffic into NAT node
ipfw add 300 netgraph 61 all from any to any in via fxp0
ipfw add 400 netgraph 60 all from any to any out via fxp0

# Let packets continue with after being (de)aliased
sysctl net.inet.ip.fw.one_pass=0
.Ed
.Pp
.Nm
node can simply be inserted right after
.Xr ng_iface
node.
In the following example we perform masquerading on a
serial line with HDLC encapsulation.
.Bd -literal -offset indent
/usr/sbin/ngctl -f- <<-SEQ
	mkpeer cp0: cisco rawdata downstream
	name cp0:rawdata hdlc
	mkpeer hdlc: nat inet in
	name hdlc:inet nat
	mkpeer nat: iface out inet
	msg nat: setaliasaddr x.y.8.35
SEQ
ifconfig ng0 x.y.8.35 x.y.8.1
.Ed
.Sh SEE ALSO
.Xr libalias 3 ,
.Xr natd 8 ,
.Xr ng_ipfw 4 ,
.Xr ngctl 8
.Sh HISTORY
The
.Nm
node type was implemented in
.Fx 6.0 .
.Sh AUTHORS
.An Gleb Smirnoff Aq glebius@FreeBSD.org