326 lines
9.2 KiB
Groff
326 lines
9.2 KiB
Groff
.\" Copyright (c) 2005 Gleb Smirnoff <glebius@FreeBSD.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd March 1, 2008
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.Dt NG_NAT 4
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.Os
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.Sh NAME
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.Nm ng_nat
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.Nd "NAT netgraph node type"
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.Sh SYNOPSIS
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.In netgraph/ng_nat.h
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.Sh DESCRIPTION
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An
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.Nm
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node performs network address translation (NAT) of packets
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passing through it.
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A
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.Nm nat
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node uses
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.Xr libalias 3
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engine for packet aliasing.
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.Sh HOOKS
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This node type has two hooks:
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.Bl -tag -width indent
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.It Va out
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Packets received on this hook are considered outgoing and will be
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masqueraded to a configured address.
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.It Va in
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Packets coming on this hook are considered incoming and will be
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dealiased.
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.El
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.Sh CONTROL MESSAGES
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This node type supports the generic control messages, plus the following:
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.Bl -tag -width indent
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.It Dv NGM_NAT_SET_IPADDR Pq Li setaliasaddr
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Configure aliasing address for a node.
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After both hooks have been connected and aliasing address was configured,
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a node is ready for aliasing operation.
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.It Dv NGM_NAT_SET_MODE Pq Li setmode
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Set node's operation mode using supplied
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.Vt "struct ng_nat_mode" .
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.Bd -literal
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struct ng_nat_mode {
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uint32_t flags;
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uint32_t mask;
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};
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/* Supported flags: */
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#define NG_NAT_LOG 0x01
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#define NG_NAT_DENY_INCOMING 0x02
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#define NG_NAT_SAME_PORTS 0x04
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#define NG_NAT_UNREGISTERED_ONLY 0x10
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#define NG_NAT_RESET_ON_ADDR_CHANGE 0x20
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#define NG_NAT_PROXY_ONLY 0x40
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#define NG_NAT_REVERSE 0x80
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.Ed
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.It Dv NGM_NAT_SET_TARGET Pq Li settarget
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Configure target address for a node.
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When an incoming packet not associated with any pre-existing aliasing
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link arrives at the host machine, it will be sent to the specified address.
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.It Dv NGM_NAT_REDIRECT_PORT Pq Li redirectport
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Redirect incoming connections arriving to given port(s) to
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another host and port(s).
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The following
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.Vt "struct ng_nat_redirect_port"
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must be supplied as argument.
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.Bd -literal
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#define NG_NAT_DESC_LENGTH 64
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struct ng_nat_redirect_port {
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struct in_addr local_addr;
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struct in_addr alias_addr;
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struct in_addr remote_addr;
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uint16_t local_port;
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uint16_t alias_port;
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uint16_t remote_port;
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uint8_t proto;
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char description[NG_NAT_DESC_LENGTH];
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};
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.Ed
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.Pp
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Redirection is assigned an unique ID which is returned as
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response to this message, and
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information about redirection added to
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list of static redirects which later can be retrieved by
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.Dv NGM_NAT_LIST_REDIRECTS
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message.
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.It Dv NGM_NAT_REDIRECT_ADDR Pq Li redirectaddr
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Redirect traffic for public IP address to a machine on the
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local network.
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This function is known as
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.Em static NAT .
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The following
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.Vt "struct ng_nat_redirect_addr"
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must be supplied as argument.
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.Bd -literal
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struct ng_nat_redirect_addr {
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struct in_addr local_addr;
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struct in_addr alias_addr;
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char description[NG_NAT_DESC_LENGTH];
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};
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.Ed
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.Pp
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Unique ID for this redirection is returned as response to this message.
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.It Dv NGM_NAT_REDIRECT_PROTO Pq Li redirectproto
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Redirect incoming IP packets of protocol
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.Va proto
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(see
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.Xr protocols 5 )
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to a machine on the local network.
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The following
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.Vt "struct ng_nat_redirect_proto"
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must be supplied as argument.
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.Bd -literal
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struct ng_nat_redirect_proto {
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struct in_addr local_addr;
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struct in_addr alias_addr;
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struct in_addr remote_addr;
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uint8_t proto;
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char description[NG_NAT_DESC_LENGTH];
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};
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.Ed
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.Pp
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Unique ID for this redirection is returned as response to this message.
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.It Dv NGM_NAT_REDIRECT_DYNAMIC Pq Li redirectdynamic
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Mark redirection with specified ID as dynamic, i.e., it will serve
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for exactly one next connection and then will be automatically
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deleted from internal links table.
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Only fully specified links can be made dynamic.
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The redirection with this ID is also immediately deleted from
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user-visible list of static redirects (available through
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.Dv NGM_NAT_LIST_REDIRECTS
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message).
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.It Dv NGM_NAT_REDIRECT_DELETE Pq Li redirectdelete
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Delete redirection with specified ID (currently active
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connections are not affected).
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.It Dv NGM_NAT_ADD_SERVER Pq Li addserver
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Add another server to a pool.
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This is used to transparently offload network load on a single server
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and distribute the load across a pool of servers, also known as
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.Em LSNAT
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(RFC 2391).
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The following
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.Vt "struct ng_nat_add_server"
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must be supplied as argument.
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.Bd -literal
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struct ng_nat_add_server {
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uint32_t id;
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struct in_addr addr;
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uint16_t port;
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};
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.Ed
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.Pp
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First, the redirection is set up by
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.Dv NGM_NAT_REDIRECT_PORT
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or
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.Dv NGM_NAT_REDIRECT_ADDR .
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Then, ID of that redirection is used in multiple
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.Dv NGM_NAT_ADD_SERVER
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messages to add necessary number of servers.
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For redirections created by
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.Dv NGM_NAT_REDIRECT_ADDR ,
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the
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.Va port
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is ignored and could have any value.
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Original redirection's parameters
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.Va local_addr
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and
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.Va local_port
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are also ignored after
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.Dv NGM_NAT_ADD_SERVER
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was used (they are effectively replaced by server pool).
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.It Dv NGM_NAT_LIST_REDIRECTS Pq Li listredirects
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Return list of configured static redirects as
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.Vt "struct ng_nat_list_redirects" .
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.Bd -literal
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struct ng_nat_listrdrs_entry {
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uint32_t id; /* Anything except zero */
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struct in_addr local_addr;
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struct in_addr alias_addr;
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struct in_addr remote_addr;
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uint16_t local_port;
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uint16_t alias_port;
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uint16_t remote_port;
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uint16_t proto; /* Valid proto or NG_NAT_REDIRPROTO_ADDR */
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uint16_t lsnat; /* LSNAT servers count */
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char description[NG_NAT_DESC_LENGTH];
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};
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struct ng_nat_list_redirects {
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uint32_t total_count;
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struct ng_nat_listrdrs_entry redirects[];
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};
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#define NG_NAT_REDIRPROTO_ADDR (IPPROTO_MAX + 3)
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.Ed
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.Pp
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Entries of the
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.Va redirects
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array returned in the unified format for all redirect types.
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Ports are meaningful only if protocol is either TCP or UDP
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and
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.Em static NAT
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redirection (created by
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.Dv NGM_NAT_REDIRECT_ADDR )
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is indicated by
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.Va proto
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set to
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.Dv NG_NAT_REDIRPROTO_ADDR .
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If
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.Va lsnat
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servers counter is greater than zero, then
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.Va local_addr
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and
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.Va local_port
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are also meaningless.
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.It Dv NGM_NAT_PROXY_RULE Pq Li proxyrule
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Specify a transparent proxying rule (string must be
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supplied as argument).
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See
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.Xr libalias 3
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for details.
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.El
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.Pp
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In all redirection messages
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.Va local_addr
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and
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.Va local_port
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mean address and port of target machine in the internal network,
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respectively.
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If
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.Va alias_addr
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is zero, then default aliasing address (set by
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.Dv NGM_NAT_SET_IPADDR )
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is used.
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Connections can also be restricted to be accepted only
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from specific external machines by using non-zero
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.Va remote_addr
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and/or
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.Va remote_port .
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Each redirection assigned an ID which can be later used for
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redirection manipulation on individual basis (e.g., removal).
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This ID guaranteed to be unique until the node shuts down
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(it will not be reused after deletion), and is returned to
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user after making each new redirection or can be found in
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the stored list of all redirections.
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The
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.Va description
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passed to and from node unchanged, together with ID providing
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a way for several entities to concurrently manipulate
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redirections in automated way.
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.Sh SHUTDOWN
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This node shuts down upon receipt of a
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.Dv NGM_SHUTDOWN
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control message, or when both hooks are disconnected.
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.Sh EXAMPLES
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In the following example, the packets are injected into a
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.Nm nat
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node using the
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.Xr ng_ipfw 4
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node.
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.Bd -literal -offset indent
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# Create NAT node
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ngctl mkpeer ipfw: nat 60 out
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ngctl name ipfw:60 nat
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ngctl connect ipfw: nat: 61 in
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ngctl msg nat: setaliasaddr x.y.35.8
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# Divert traffic into NAT node
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ipfw add 300 netgraph 61 all from any to any in via fxp0
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ipfw add 400 netgraph 60 all from any to any out via fxp0
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# Let packets continue with after being (de)aliased
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sysctl net.inet.ip.fw.one_pass=0
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.Ed
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.Pp
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The
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.Nm
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node can be inserted right after the
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.Xr ng_iface 4
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node in the graph.
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In the following example, we perform masquerading on a
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serial line with HDLC encapsulation.
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.Bd -literal -offset indent
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/usr/sbin/ngctl -f- <<-SEQ
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mkpeer cp0: cisco rawdata downstream
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name cp0:rawdata hdlc
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mkpeer hdlc: nat inet in
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name hdlc:inet nat
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mkpeer nat: iface out inet
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msg nat: setaliasaddr x.y.8.35
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SEQ
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ifconfig ng0 x.y.8.35 x.y.8.1
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.Ed
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.Sh SEE ALSO
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.Xr libalias 3 ,
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.Xr ng_ipfw 4 ,
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.Xr natd 8 ,
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.Xr ngctl 8
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.Sh HISTORY
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The
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.Nm
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node type was implemented in
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.Fx 6.0 .
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.Sh AUTHORS
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.An Gleb Smirnoff Aq glebius@FreeBSD.org
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