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mdoc style cleanup.

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Reviewed by:	sheldonh
This commit is contained in:
Alexander Langer 2000-06-26 14:44:31 +00:00
parent 47fdd692c6
commit 27d19e4e41
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=62121
1 changed files with 192 additions and 168 deletions
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sbin/natd/natd.8
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@ -47,97 +47,117 @@ Network Address Translation Daemon
This program provides a Network Address Translation facility for use This program provides a Network Address Translation facility for use
with with
.Xr divert 4 .Xr divert 4
sockets under FreeBSD. It is intended for use with NICs - if you want sockets under FreeBSD.
to do NAT on a PPP link, use the -nat switch to It is intended for use with NICs -
if you want to do NAT on a PPP link,
use the -nat switch to
.Xr ppp 8 . .Xr ppp 8 .
.Pp .Pp
.Nm Natd .Nm Natd
normally runs in the background as a daemon. It is passed raw IP packets normally runs in the background as a daemon.
as they travel into and out of the machine, and will possibly change these It is passed raw IP packets as they travel into and out of the machine,
before re-injecting them back into the IP packet stream. and will possibly change these before re-injecting them back
into the IP packet stream.
.Pp .Pp
.Nm Natd .Nm Natd
changes all packets destined for another host so that their source changes all packets destined for another host
IP number is that of the current machine. For each packet changed so that their source IP number is that of the current machine.
in this manner, an internal table entry is created to record this For each packet changed in this manner,
fact. The source port number is also changed to indicate the an internal table entry is created to record this fact.
table entry applying to the packet. Packets that are received with The source port number is also changed
a target IP of the current host are checked against this internal to indicate the table entry applying to the packet.
table. If an entry is found, it is used to determine the correct Packets that are received with a target IP of the current host
target IP number and port to place in the packet. are checked against this internal table.
If an entry is found,
it is used to determine the correct target IP number and port
to place in the packet.
.Pp .Pp
The following command line options are available. The following command line options are available.
.Bl -tag -width Fl .Bl -tag -width Fl
.It Fl log | l .It Fl log | l
Log various aliasing statistics and information to the file Log various aliasing statistics and information to the file
.Pa /var/log/alias.log . .Pa /var/log/alias.log .
This file is truncated each time natd is started. This file is truncated each time natd is started.
.It Fl deny_incoming | d .It Fl deny_incoming | d
Reject packets destined for the current IP number that have no entry Reject packets destined for the current IP number
in the internal translation table. that have no entry in the internal translation table.
.It Fl log_denied .It Fl log_denied
Log denied incoming packets via syslog (see also log_facility) Log denied incoming packets via syslog (see also log_facility)
.It Fl log_facility Ar facility_name .It Fl log_facility Ar facility_name
Use specified log facility when logging information via syslog. Use specified log facility when logging information via syslog.
Facility names are as in Facility names are as in
.Xr syslog.conf 5 .Xr syslog.conf 5
.It Fl use_sockets | s .It Fl use_sockets | s
Allocate a Allocate a
.Xr socket 2 .Xr socket 2
in order to establish an FTP data or IRC DCC send connection. This in order to establish an FTP data or IRC DCC send connection.
option uses more system resources, but guarantees successful connections This option uses more system resources,
when port numbers conflict. but guarantees successful connections when port numbers conflict.
.It Fl same_ports | m .It Fl same_ports | m
Try to keep the same port number when altering outgoing packets. Try to keep the same port number when altering outgoing packets.
With this option, protocols such as RPC will have a better chance With this option,
of working. If it is not possible to maintain the port number, it protocols such as RPC will have a better chance of working.
will be silently changed as per normal. If it is not possible to maintain the port number,
it will be silently changed as per normal.
.It Fl verbose | v .It Fl verbose | v
Don't call Don't call
.Xr fork 2 .Xr fork 2
or or
.Xr daemon 3 .Xr daemon 3
on startup. Instead, stay attached to the controling terminal and on startup.
display all packet alterations to the standard output. This option Instead, stay attached to the controling terminal and
should only be used for debugging purposes. display all packet alterations to the standard output.
This option should only be used for debugging purposes.
.It Fl unregistered_only | u .It Fl unregistered_only | u
Only alter outgoing packets with an unregistered source address. Only alter outgoing packets with an unregistered source address.
According to rfc 1918, unregistered source addresses are 10.0.0.0/8, According to rfc 1918,
172.16.0.0/12 and 192.168.0.0/16. unregistered source addresses are 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16.
.It Fl redirect_port Ar proto targetIP:targetPORT[-targetPORT] [aliasIP:]aliasPORT[-aliasPORT] [remoteIP[:remotePORT[-remotePORT]]] .It Fl redirect_port Ar proto targetIP:targetPORT[-targetPORT] [aliasIP:]aliasPORT[-aliasPORT] [remoteIP[:remotePORT[-remotePORT]]]
Redirect incoming connections arriving to given port(s) to another host Redirect incoming connections arriving to given port(s) to another host
and port(s). and port(s).
Proto is either tcp or udp, targetIP is the desired target IP .Ar Proto
number, targetPORT is the desired target PORT number or range, aliasPORT is either tcp or udp,
is the requested PORT number or range, and aliasIP is the aliasing address. .Ar targetIP
RemoteIP and remotePORT can be used to specify the connection is the desired target IP number,
more accurately if necessary. .Ar targetPORT
The targetPORT range and aliasPORT range need not be the same numerically, is the desired target PORT number or range,
.Ar aliasPORT
is the requested PORT number or range,
and
.Ar aliasIP
is the aliasing address.
.Ar RemoteIP
and
.Ar remotePORT
can be used to specify the connection more accurately if necessary.
The
.Ar targetPORT
range and
.Ar aliasPORT
range need not be the same numerically,
but must have the same size. but must have the same size.
If remotePORT is not specified, it is assumed to be all ports. If
If remotePORT is specified, it must match the size of targetPORT, or be 0 .Ar remotePORT
is not specified,
it is assumed to be all ports.
If
.Ar remotePORT
is specified,
it must match the size of targetPORT,
or be 0
(all ports). (all ports).
For example, the argument For example,
the argument
.Pp
.Dl Ar tcp inside1:telnet 6666 .Dl Ar tcp inside1:telnet 6666
.Pp
means that incoming tcp packets destined for port 6666 on this machine will means that incoming tcp packets destined for port 6666 on this machine will
be sent to the telnet port on the inside1 machine. be sent to the telnet port on the inside1 machine.
.Pp
.Dl Ar tcp inside2:2300-2399 3300-3399 .Dl Ar tcp inside2:2300-2399 3300-3399
.Pp
will redirect incoming connections on ports 3300-3399 to host will redirect incoming connections on ports 3300-3399 to host
inside2, ports 2300-2399. inside2, ports 2300-2399.
The mapping is 1:1 meaning port 3300 maps to 2300, 3301 maps to 2301, etc. The mapping is 1:1 meaning port 3300 maps to 2300, 3301 maps to 2301, etc.
@ -155,34 +175,34 @@ address and vice versa.
.Pp .Pp
If If
.Ar publicIP .Ar publicIP
is not specified, then the default aliasing address is used. is not specified,
then the default aliasing address is used.
If If
.Ar remoteIP .Ar remoteIP
is specified, then only packets coming from/to is specified,
then only packets coming from/to
.Ar remoteIP .Ar remoteIP
will match the rule. will match the rule.
.It Fl redirect_address Ar localIP publicIP .It Fl redirect_address Ar localIP publicIP
Redirect traffic for public IP address to a machine on the local Redirect traffic for public IP address to a machine on the local network.
network. This function is known as "static NAT".
This function is known as "static NAT". Normally static NAT Normally static NAT is useful
is useful if your ISP has allocated a small block of IP addresses to you, if your ISP has allocated a small block of IP addresses to you,
but it can even be used in the case of single address: but it can even be used in the case of single address:
.Pp
redirect_address 10.0.0.8 0.0.0.0 .Dl Ar redirect_address 10.0.0.8 0.0.0.0
.Pp
The above command would redirect all incoming traffic The above command would redirect all incoming traffic to machine 10.0.0.8.
to machine 10.0.0.8. .Pp
If several address aliases specify the same public address as follows
If several address aliases specify the same public address .Pp
as follows .Dl Ar redirect_address 192.168.0.2 public_addr
.Dl Ar redirect_address 192.168.0.3 public_addr
redirect_address 192.168.0.2 public_addr .Dl Ar redirect_address 192.168.0.4 public_addr
redirect_address 192.168.0.3 public_addr .Pp
redirect_address 192.168.0.4 public_addr
the incoming traffic will be directed to the last the incoming traffic will be directed to the last
translated local address (192.168.0.4), but outgoing translated local address (192.168.0.4),
traffic to the first two addresses will still be aliased but outgoing traffic to the first two addresses will still be aliased
to specified public address. to specified public address.
.It Fl redirect_port Ar proto Xo .It Fl redirect_port Ar proto Xo
.Ar targetIP Ns : Ns Xo .Ar targetIP Ns : Ns Xo
@ -216,13 +236,15 @@ distribute the load across a pool of servers.
This function is known as This function is known as
.Em LSNAT .Em LSNAT
(RFC 2391). (RFC 2391).
For example, the argument For example,
the argument
.Pp .Pp
.Dl Ar tcp www1:http,www2:http,www3:http www:http .Dl Ar tcp www1:http,www2:http,www3:http www:http
.Pp .Pp
means that incoming HTTP requests for host www will be transparently means that incoming HTTP requests for host www will be transparently
redirected to one of the www1, www2 or www3, where a host is selected redirected to one of the www1, www2 or www3,
simply on a round-robin basis, without regard to load on the net. where a host is selected simply on a round-robin basis,
without regard to load on the net.
.It Fl dynamic .It Fl dynamic
If the If the
.Fl n .Fl n
@ -232,20 +254,18 @@ option is used,
.Nm .Nm
will monitor the routing socket for alterations to the will monitor the routing socket for alterations to the
.Ar interface .Ar interface
passed. If the interfaces IP number is changed, passed.
If the interfaces IP number is changed,
.Nm .Nm
will dynamically alter its concept of the alias address. will dynamically alter its concept of the alias address.
.It Fl i | inport Ar inport .It Fl i | inport Ar inport
Read from and write to Read from and write to
.Ar inport , .Ar inport ,
treating all packets as packets coming into the machine. treating all packets as packets coming into the machine.
.It Fl o | outport Ar outport .It Fl o | outport Ar outport
Read from and write to Read from and write to
.Ar outport , .Ar outport ,
treating all packets as packets going out of the machine. treating all packets as packets going out of the machine.
.It Fl p | port Ar port .It Fl p | port Ar port
Read from and write to Read from and write to
.Ar port , .Ar port ,
@ -257,45 +277,54 @@ is not numeric, it is searched for in the
.Pa /etc/services .Pa /etc/services
database using the database using the
.Xr getservbyname 3 .Xr getservbyname 3
function. If this flag is not specified, the divert port named natd will function.
be used as a default. An example entry in the If this flag is not specified,
the divert port named natd will be used as a default.
An example entry in the
.Pa /etc/services .Pa /etc/services
database would be: database would be:
.Pp
natd 8668/divert # Network Address Translation socket natd 8668/divert # Network Address Translation socket
.Pp
Refer to Refer to
.Xr services 5 .Xr services 5
for further details. for further details.
.It Fl a | alias_address Ar address .It Fl a | alias_address Ar address
Use Use
.Ar address .Ar address
as the alias address. If this option is not specified, the as the alias address.
If this option is not specified, the
.Fl n .Fl n
or or
.Fl interface .Fl interface
option must be used. The specified address should be the address assigned option must be used.
The specified address should be the address assigned
to the public network interface. to the public network interface.
.Pp .Pp
All data passing out through this addresses interface will be rewritten All data passing out through this addresses interface will be rewritten
with a source address equal to with a source address equal to
.Ar address . .Ar address .
All data arriving at the interface from outside will be checked to All data arriving at the interface from outside will be checked to
see if it matches any already-aliased outgoing connection. If it does, see if it matches any already-aliased outgoing connection.
the packet is altered accordingly. If not, all If it does,
the packet is altered accordingly.
If not,
all
.Fl redirect_port .Fl redirect_port
and and
.Fl redirect_address .Fl redirect_address
assignments are checked and actioned. If no other action can be made, assignments are checked and actioned.
If no other action can be made,
and if and if
.Fl deny_incoming .Fl deny_incoming
is not specified, the packet is delivered to the local machine and port is not specified,
the packet is delivered to the local machine and port
as specified in the packet. as specified in the packet.
.It Fl t | target_address Ar address .It Fl t | target_address Ar address
Set the target address. Set the target address.
When an incoming packet not associated with any pre-existing link When an incoming packet not associated with any pre-existing link
arrives at the host machine, it will be sent to the specified arrives at the host machine,
it will be sent to the specified
.Ar address . .Ar address .
.Pp .Pp
The target address may be set to The target address may be set to
@ -305,21 +334,22 @@ in which case all new incoming packets go to the alias address set by
or or
.Fl interface . .Fl interface .
.Pp .Pp
If this option is not used, or called with the argument If this option is not used,
or called with the argument
.Dq 0.0.0.0 , .Dq 0.0.0.0 ,
then all new incoming packets go to the address specified in then all new incoming packets go to the address specified in the packet.
the packet.
This allows external machines to talk directly to internal machines if This allows external machines to talk directly to internal machines if
they can route packets to the machine in question. they can route packets to the machine in question.
.It Fl n | interface Ar interface .It Fl n | interface Ar interface
Use Use
.Ar interface .Ar interface
to determine the alias address. If there is a possibility that the to determine the alias address.
IP number associated with If there is a possibility that the IP number associated with
.Ar interface .Ar interface
may change, the may change, the
.Fl dynamic .Fl dynamic
flag should also be used. If this option is not specified, the flag should also be used.
If this option is not specified, the
.Fl a .Fl a
or or
.Fl alias_address .Fl alias_address
@ -332,20 +362,22 @@ must be the public network interface.
Read configuration from Read configuration from
.Ar configfile . .Ar configfile .
.Ar Configfile .Ar Configfile
contains a list of options, one per line in the same form as the contains a list of options,
long form of the above command line flags. For example, the line one per line in the same form as the long form of the above command line flags.
For example, the line
alias_address 158.152.17.1 .Pp
alias_address 158.152.17.1
would specify an alias address of 158.152.17.1. Options that don't .Pp
take an argument are specified with an option of would specify an alias address of 158.152.17.1.
Options that don't take an argument are specified with an option of
.Ar yes .Ar yes
or or
.Ar no .Ar no
in the configuration file. For example, the line in the configuration file.
For example, the line
log yes .Pp
log yes
.Pp
is synonomous with is synonomous with
.Fl log . .Fl log .
.Pp .Pp
@ -353,23 +385,21 @@ Trailing spaces and empty lines are ignored.
A A
.Ql \&# .Ql \&#
sign will mark the rest of the line as a comment. sign will mark the rest of the line as a comment.
.It Fl reverse .It Fl reverse
Reverse operation of natd. Reverse operation of natd.
This can be useful in some This can be useful in some transparent proxying situations,
transparent proxying situations when outgoing traffic when outgoing traffic is redirected to the local machine
is redirected to the local machine and natd is running on the and natd is running on the incoming interface
incoming interface (it usually runs on the outgoing interface). (it usually runs on the outgoing interface).
.It Fl proxy_only .It Fl proxy_only
Force natd to perform transparent proxying Force natd to perform transparent proxying
only. only.
Normal address translation is not performed. Normal address translation is not performed.
.It Fl proxy_rule Ar [type encode_ip_hdr|encode_tcp_stream] port xxxx server a.b.c.d:yyyy .It Fl proxy_rule Ar [type encode_ip_hdr|encode_tcp_stream] port xxxx server a.b.c.d:yyyy
Enable transparent proxying. Enable transparent proxying.
Packets with the given port going through this Packets with the given port going through this host to any other host
host to any other host are redirected to the given server and port. are redirected to the given server and port.
Optionally, the original target address can be encoded into the packet. Optionally, the original target address can be encoded into the packet.
Use Use
.Dq encode_ip_hdr .Dq encode_ip_hdr
@ -377,132 +407,126 @@ to put this information into the IP option field or
.Dq encode_tcp_stream .Dq encode_tcp_stream
to inject the data into the beginning of the TCP stream. to inject the data into the beginning of the TCP stream.
.El .El
.Sh RUNNING NATD .Sh RUNNING NATD
The following steps are necessary before attempting to run The following steps are necessary before attempting to run
.Nm natd : .Nm natd :
.Bl -enum .Bl -enum
.It .It
Get FreeBSD version 2.2 or higher. Versions before this do not support Get FreeBSD version 2.2 or higher. Versions before this do not support
.Xr divert 4 .Xr divert 4
sockets. sockets.
.It .It
Build a custom kernel with the following options: Build a custom kernel with the following options:
.Pp
options IPFIREWALL options IPFIREWALL
options IPDIVERT options IPDIVERT
.Pp
Refer to the handbook for detailed instructions on building a custom Refer to the handbook for detailed instructions on building a custom
kernel. kernel.
.It .It
Ensure that your machine is acting as a gateway. This can be done by Ensure that your machine is acting as a gateway.
specifying the line This can be done by specifying the line
.Pp
gateway_enable=YES gateway_enable=YES
.Pp
in in
.Pa /etc/rc.conf , .Pa /etc/rc.conf ,
or using the command or using the command
.Pp
sysctl -w net.inet.ip.forwarding=1 .Nm sysctl Fl w Ar net.inet.ip.forwarding=1
.It .It
If you wish to use the If you wish to use the
.Fl n .Fl n
or or
.Fl interface .Fl interface
flags, make sure that your interface is already configured. If, for flags,
example, you wish to specify tun0 as your make sure that your interface is already configured.
If, for example, you wish to specify tun0 as your
.Ar interface , .Ar interface ,
and you're using and you're using
.Xr ppp 8 .Xr ppp 8
on that interface, you must make sure that you start on that interface,
you must make sure that you start
.Nm ppp .Nm ppp
prior to starting prior to starting
.Nm natd . .Nm natd .
.It .It
Create an entry in Create an entry in
.Pa /etc/services : .Pa /etc/services :
.Pp
natd 8668/divert # Network Address Translation socket natd 8668/divert # Network Address Translation socket
.Pp
This gives a default for the This gives a default for the
.Fl p .Fl p
or or
.Fl port .Fl port
flag. flag.
.El .El
.Pp .Pp
Running Running
.Nm .Nm
is fairly straight forward. The line is fairly straight forward. The line
.Pp
natd -interface ed0 .Nm natd Fl interface Ar ed0
.Pp
should suffice in most cases (substituting the correct interface name). Once should suffice in most cases
(substituting the correct interface name).
Once
.Nm .Nm
is running, you must ensure that traffic is diverted to natd: is running,
you must ensure that traffic is diverted to natd:
.Bl -enum .Bl -enum
.It .It
You will need to adjust the You will need to adjust the
.Pa /etc/rc.firewall .Pa /etc/rc.firewall
script to taste. If you're not interested in having a firewall, the script to taste. If you're not interested in having a firewall, the
following lines will do: following lines will do:
.Pp
/sbin/ipfw -f flush /sbin/ipfw -f flush
/sbin/ipfw add divert natd all from any to any via ed0 /sbin/ipfw add divert natd all from any to any via ed0
/sbin/ipfw add pass all from any to any /sbin/ipfw add pass all from any to any
.Pp
The second line depends on your interface (change ed0 as appropriate) The second line depends on your interface (change ed0 as appropriate)
and assumes that you've updated and assumes that you've updated
.Pa /etc/services .Pa /etc/services
with the natd entry as above. If you specify real firewall rules, it's with the natd entry as above.
best to specify line 2 at the start of the script so that If you specify real firewall rules,
it's best to specify line 2 at the start of the script so that
.Nm .Nm
sees all packets before they are dropped by the firewall. sees all packets before they are dropped by the firewall.
.Pp .Pp
After translation by After translation by
.Nm natd , .Nm natd ,
packets re-enter the firewall at the rule number following the rule number packets re-enter the firewall at the rule number following the rule number
that caused the diversion (not the next rule if there are several at the that caused the diversion
same number). (not the next rule if there are several at the same number).
.It .It
Enable your firewall by setting Enable your firewall by setting
.Pp
firewall_enable=YES firewall_enable=YES
.Pp
in in
.Pa /etc/rc.conf . .Pa /etc/rc.conf .
This tells the system startup scripts to run the This tells the system startup scripts to run the
.Pa /etc/rc.firewall .Pa /etc/rc.firewall
script. If you don't wish to reboot now, just run this by hand from the script.
console. NEVER run this from a virtual session unless you put it into If you don't wish to reboot now, just run this by hand from the console.
the background. If you do, you'll lock yourself out after the flush NEVER run this from a virtual session unless you put it into the background.
takes place, and execution of If you do, you'll lock yourself out after the flush takes place,
and execution of
.Pa /etc/rc.firewall .Pa /etc/rc.firewall
will stop at this point - blocking all accesses permanently. Running will stop at this point - blocking all accesses permanently.
the script in the background should be enough to prevent this disaster. Running the script in the background should be enough to prevent this disaster.
.El .El
.Sh SEE ALSO .Sh SEE ALSO
.Xr socket 2 , .Xr socket 2 ,
.Xr getservbyname 3 , .Xr getservbyname 3 ,
.Xr divert 4 , .Xr divert 4 ,
.Xr services 5 , .Xr services 5 ,
.Xr ipfw 8 .Xr ipfw 8
.Sh AUTHORS .Sh AUTHORS
This program is the result of the efforts of many people at different This program is the result of the efforts of many people at different
times: times:
.An Archie Cobbs Aq archie@whistle.com .An Archie Cobbs Aq archie@whistle.com
(divert sockets) (divert sockets)
.An Charles Mott Aq cmott@scientech.com .An Charles Mott Aq cmott@scientech.com