404 lines
11 KiB
Groff
404 lines
11 KiB
Groff
.\" Copyright (c) 2005 Gleb Smirnoff <glebius@FreeBSD.org>
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd December 12, 2018
|
|
.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.
|
|
A
|
|
.Nm nat
|
|
node uses
|
|
.Xr libalias 3
|
|
engine for packet aliasing.
|
|
.Sh HOOKS
|
|
This node type has two hooks:
|
|
.Bl -tag -width ".Va out"
|
|
.It Va out
|
|
Packets received on this hook are considered outgoing and will be
|
|
masqueraded to a configured address.
|
|
.It Va in
|
|
Packets coming on this hook are considered incoming and will 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 Ic setaliasaddr
|
|
Configure aliasing address for a node.
|
|
After both hooks have been connected and aliasing address was configured,
|
|
a node is ready for aliasing operation.
|
|
.It Dv NGM_NAT_SET_MODE Pq Ic setmode
|
|
Set node's operation mode using supplied
|
|
.Vt "struct ng_nat_mode" .
|
|
.Bd -literal
|
|
struct ng_nat_mode {
|
|
uint32_t flags;
|
|
uint32_t mask;
|
|
};
|
|
/* Supported flags: */
|
|
#define NG_NAT_LOG 0x01
|
|
#define NG_NAT_DENY_INCOMING 0x02
|
|
#define NG_NAT_SAME_PORTS 0x04
|
|
#define NG_NAT_UNREGISTERED_ONLY 0x10
|
|
#define NG_NAT_RESET_ON_ADDR_CHANGE 0x20
|
|
#define NG_NAT_PROXY_ONLY 0x40
|
|
#define NG_NAT_REVERSE 0x80
|
|
.Ed
|
|
.It Dv NGM_NAT_SET_TARGET Pq Ic settarget
|
|
Configure target address for a node.
|
|
When an incoming packet not associated with any pre-existing aliasing
|
|
link arrives at the host machine, it will be sent to the specified address.
|
|
.It Dv NGM_NAT_REDIRECT_PORT Pq Ic redirectport
|
|
Redirect incoming connections arriving to given port(s) to
|
|
another host and port(s).
|
|
The following
|
|
.Vt "struct ng_nat_redirect_port"
|
|
must be supplied as argument.
|
|
.Bd -literal
|
|
#define NG_NAT_DESC_LENGTH 64
|
|
struct ng_nat_redirect_port {
|
|
struct in_addr local_addr;
|
|
struct in_addr alias_addr;
|
|
struct in_addr remote_addr;
|
|
uint16_t local_port;
|
|
uint16_t alias_port;
|
|
uint16_t remote_port;
|
|
uint8_t proto;
|
|
char description[NG_NAT_DESC_LENGTH];
|
|
};
|
|
.Ed
|
|
.Pp
|
|
Redirection is assigned an unique ID which is returned as
|
|
response to this message, and
|
|
information about redirection added to
|
|
list of static redirects which later can be retrieved by
|
|
.Dv NGM_NAT_LIST_REDIRECTS
|
|
message.
|
|
.It Dv NGM_NAT_REDIRECT_ADDR Pq Ic redirectaddr
|
|
Redirect traffic for public IP address to a machine on the
|
|
local network.
|
|
This function is known as
|
|
.Em static NAT .
|
|
The following
|
|
.Vt "struct ng_nat_redirect_addr"
|
|
must be supplied as argument.
|
|
.Bd -literal
|
|
struct ng_nat_redirect_addr {
|
|
struct in_addr local_addr;
|
|
struct in_addr alias_addr;
|
|
char description[NG_NAT_DESC_LENGTH];
|
|
};
|
|
.Ed
|
|
.Pp
|
|
Unique ID for this redirection is returned as response to this message.
|
|
.It Dv NGM_NAT_REDIRECT_PROTO Pq Ic redirectproto
|
|
Redirect incoming IP packets of protocol
|
|
.Va proto
|
|
(see
|
|
.Xr protocols 5 )
|
|
to a machine on the local network.
|
|
The following
|
|
.Vt "struct ng_nat_redirect_proto"
|
|
must be supplied as argument.
|
|
.Bd -literal
|
|
struct ng_nat_redirect_proto {
|
|
struct in_addr local_addr;
|
|
struct in_addr alias_addr;
|
|
struct in_addr remote_addr;
|
|
uint8_t proto;
|
|
char description[NG_NAT_DESC_LENGTH];
|
|
};
|
|
.Ed
|
|
.Pp
|
|
Unique ID for this redirection is returned as response to this message.
|
|
.It Dv NGM_NAT_REDIRECT_DYNAMIC Pq Ic redirectdynamic
|
|
Mark redirection with specified ID as dynamic, i.e., it will serve
|
|
for exactly one next connection and then will be automatically
|
|
deleted from internal links table.
|
|
Only fully specified links can be made dynamic.
|
|
The redirection with this ID is also immediately deleted from
|
|
user-visible list of static redirects (available through
|
|
.Dv NGM_NAT_LIST_REDIRECTS
|
|
message).
|
|
.It Dv NGM_NAT_REDIRECT_DELETE Pq Ic redirectdelete
|
|
Delete redirection with specified ID (currently active
|
|
connections are not affected).
|
|
.It Dv NGM_NAT_ADD_SERVER Pq Ic addserver
|
|
Add another server to a pool.
|
|
This is used to transparently offload network load on a single server
|
|
and distribute the load across a pool of servers, also known as
|
|
.Em LSNAT
|
|
(RFC 2391).
|
|
The following
|
|
.Vt "struct ng_nat_add_server"
|
|
must be supplied as argument.
|
|
.Bd -literal
|
|
struct ng_nat_add_server {
|
|
uint32_t id;
|
|
struct in_addr addr;
|
|
uint16_t port;
|
|
};
|
|
.Ed
|
|
.Pp
|
|
First, the redirection is set up by
|
|
.Dv NGM_NAT_REDIRECT_PORT
|
|
or
|
|
.Dv NGM_NAT_REDIRECT_ADDR .
|
|
Then, ID of that redirection is used in multiple
|
|
.Dv NGM_NAT_ADD_SERVER
|
|
messages to add necessary number of servers.
|
|
For redirections created by
|
|
.Dv NGM_NAT_REDIRECT_ADDR ,
|
|
the
|
|
.Va port
|
|
is ignored and could have any value.
|
|
Original redirection's parameters
|
|
.Va local_addr
|
|
and
|
|
.Va local_port
|
|
are also ignored after
|
|
.Dv NGM_NAT_ADD_SERVER
|
|
was used (they are effectively replaced by server pool).
|
|
.It Dv NGM_NAT_LIST_REDIRECTS Pq Ic listredirects
|
|
Return list of configured static redirects as
|
|
.Vt "struct ng_nat_list_redirects" .
|
|
.Bd -literal
|
|
struct ng_nat_listrdrs_entry {
|
|
uint32_t id; /* Anything except zero */
|
|
struct in_addr local_addr;
|
|
struct in_addr alias_addr;
|
|
struct in_addr remote_addr;
|
|
uint16_t local_port;
|
|
uint16_t alias_port;
|
|
uint16_t remote_port;
|
|
uint16_t proto; /* Valid proto or NG_NAT_REDIRPROTO_ADDR */
|
|
uint16_t lsnat; /* LSNAT servers count */
|
|
char description[NG_NAT_DESC_LENGTH];
|
|
};
|
|
struct ng_nat_list_redirects {
|
|
uint32_t total_count;
|
|
struct ng_nat_listrdrs_entry redirects[];
|
|
};
|
|
#define NG_NAT_REDIRPROTO_ADDR (IPPROTO_MAX + 3)
|
|
.Ed
|
|
.Pp
|
|
Entries of the
|
|
.Va redirects
|
|
array returned in the unified format for all redirect types.
|
|
Ports are meaningful only if protocol is either TCP or UDP
|
|
and
|
|
.Em static NAT
|
|
redirection (created by
|
|
.Dv NGM_NAT_REDIRECT_ADDR )
|
|
is indicated by
|
|
.Va proto
|
|
set to
|
|
.Dv NG_NAT_REDIRPROTO_ADDR .
|
|
If
|
|
.Va lsnat
|
|
servers counter is greater than zero, then
|
|
.Va local_addr
|
|
and
|
|
.Va local_port
|
|
are also meaningless.
|
|
.It Dv NGM_NAT_PROXY_RULE Pq Ic proxyrule
|
|
Specify a transparent proxying rule (string must be
|
|
supplied as argument).
|
|
See
|
|
.Xr libalias 3
|
|
for details.
|
|
.It Dv NGM_NAT_LIBALIAS_INFO Pq Ic libaliasinfo
|
|
Return internal statistics of
|
|
.Xr libalias 3
|
|
instance as
|
|
.Vt "struct ng_nat_libalias_info" .
|
|
.Bd -literal
|
|
struct ng_nat_libalias_info {
|
|
uint32_t icmpLinkCount;
|
|
uint32_t udpLinkCount;
|
|
uint32_t tcpLinkCount;
|
|
uint32_t sctpLinkCount;
|
|
uint32_t pptpLinkCount;
|
|
uint32_t protoLinkCount;
|
|
uint32_t fragmentIdLinkCount;
|
|
uint32_t fragmentPtrLinkCount;
|
|
uint32_t sockCount;
|
|
};
|
|
.Ed
|
|
In case of
|
|
.Nm
|
|
failed to retrieve a certain counter
|
|
from its
|
|
.Xr libalias
|
|
instance, the corresponding field is returned as
|
|
.Va UINT32_MAX .
|
|
.It Dv NGM_NAT_SET_DLT Pq Ic setdlt
|
|
Sets the data link type on the
|
|
.Va in
|
|
and
|
|
.Va out
|
|
hooks.
|
|
Currently, supported types are
|
|
.Cm DLT_RAW
|
|
(raw IP datagrams , no offset applied, the default) and
|
|
.Cm DLT_EN10MB
|
|
(Ethernet). DLT_ definitions can be found in
|
|
.In net/bpf.h .
|
|
If you want to work on the
|
|
.Xr ipfw 8
|
|
level you must use no additional offset by specifying
|
|
.Cm DLT_RAW .
|
|
If, however, you attach
|
|
.Nm
|
|
to a network interface directly and
|
|
.Cm EN10MB
|
|
is specified, then the extra offset will be applied to take into account
|
|
link-level header.
|
|
In this mode the
|
|
.Nm
|
|
would also inspect appropriate type field in the Ethernet header and
|
|
pass-through any datagrams that are not IP packets.
|
|
.It Dv NGM_NAT_GET_DLT Pq Ic getdlt
|
|
This control message returns the current data link type of the
|
|
.Va in
|
|
and
|
|
.Va out
|
|
hooks.
|
|
.El
|
|
.Pp
|
|
In all redirection messages
|
|
.Va local_addr
|
|
and
|
|
.Va local_port
|
|
mean address and port of target machine in the internal network,
|
|
respectively.
|
|
If
|
|
.Va alias_addr
|
|
is zero, then default aliasing address (set by
|
|
.Dv NGM_NAT_SET_IPADDR )
|
|
is used.
|
|
Connections can also be restricted to be accepted only
|
|
from specific external machines by using non-zero
|
|
.Va remote_addr
|
|
and/or
|
|
.Va remote_port .
|
|
Each redirection assigned an ID which can be later used for
|
|
redirection manipulation on individual basis (e.g., removal).
|
|
This ID guaranteed to be unique until the node shuts down
|
|
(it will not be reused after deletion), and is returned to
|
|
user after making each new redirection or can be found in
|
|
the stored list of all redirections.
|
|
The
|
|
.Va description
|
|
passed to and from node unchanged, together with ID providing
|
|
a way for several entities to concurrently manipulate
|
|
redirections in automated way.
|
|
.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, the packets are injected into a
|
|
.Nm nat
|
|
node using the
|
|
.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
|
|
The
|
|
.Nm
|
|
node can be inserted right after the
|
|
.Xr ng_iface 4
|
|
node in the graph.
|
|
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
|
|
.Pp
|
|
The
|
|
.Nm
|
|
node can also be attached directly to the physical interface
|
|
via
|
|
.Xr ng_ether 4
|
|
node in the graph.
|
|
In the following example, we perform masquerading on a
|
|
Ethernet interface connected to a public network.
|
|
.Bd -literal -offset indent
|
|
ifconfig igb0 inet x.y.8.35 netmask 0xfffff000
|
|
route add default x.y.0.1
|
|
/usr/sbin/ngctl -f- <<-SEQ
|
|
mkpeer igb0: nat lower in
|
|
name igb0:lower igb0_NAT
|
|
connect igb0: igb0_NAT: upper out
|
|
msg igb0_NAT: setdlt 1
|
|
msg igb0_NAT: setaliasaddr x.y.8.35
|
|
SEQ
|
|
.Ed
|
|
.Sh SEE ALSO
|
|
.Xr libalias 3 ,
|
|
.Xr ng_ipfw 4 ,
|
|
.Xr natd 8 ,
|
|
.Xr ngctl 8 ,
|
|
.Xr ng_ether 8
|
|
.Sh HISTORY
|
|
The
|
|
.Nm
|
|
node type was implemented in
|
|
.Fx 6.0 .
|
|
.Sh AUTHORS
|
|
.An Gleb Smirnoff Aq Mt glebius@FreeBSD.org
|