nat - Shorewall6 one-to-one NAT file
This file is used to define one-to-one Network Address Translation (NAT).
If all you want to do is simple port forwarding, do NOT use this file. See
The columns in the file are as follows (where the column name is followed by a
different name in parentheses, the different name is used in the alternate
External IP Address - this should NOT be the
primary IP address of the interface named in the next column and must not be a
If you put ?COMMENT in this column, the rest of the line will be attached as a
comment to the Netfilter rule(s) generated by the following entries in the
file. The comment will appear delimited by "/* ... */" in the output
of "shorewall show nat"
To stop the comment from being attached to further rules, simply include
?COMMENT on a line by itself.
Interfaces that have the EXTERNAL
address. If ADD_IP_ALIASES=Yes in shorewall6.conf
(5), Shorewall will
automatically add the EXTERNAL address to this interface. Also if
ADD_IP_ALIASES=Yes, you may follow the interface name with ":" and a
to indicate that you want Shorewall to add the alias with this
name (e.g., "eth0:0"). That allows you to see the alias with
ifconfig. That is the only thing that this name is good for -- you cannot
use it anywhere else in your Shorewall configuration.
Each interface must match an entry in shorewall6-interfaces
Shorewall allows loose matches to wildcard entries in
(5). For example, ppp0 in this file will match
(5) entry that defines ppp+.
If you want to override ADD_IP_ALIASES=Yes for a particular entry, follow the
interface name with ":" and no digit (e.g.,
Internal Address (must not be a DNS
If Yes or yes, NAT will be effective from all
hosts. If No or no (or left empty) then NAT will be effective only through the
interface named in the INTERFACE
This column was formerly labelled ALL INTERFACES.
If Yes or yes, NAT will be
effective from the firewall system