NAT vs Public IP Range info needed, please

Kevin Stevens freebsd at
Sat Jun 12 12:20:43 PDT 2004

On Jun 12, 2004, at 12:11, Kevin Stevens wrote:

>> As you see, the g'way's public ip is not being used for NAT'ing 
>> internal hosts' outgoing traffic, but another ip from within the 
>> assignied public ip address range. My reading of the NAT chapter does 
>> not suggest that there is a way to define the public IP with which 
>> traffic is to be translate. Is this functionality not supported, or 
>> have I missed something when reading the various sections?
> It is AFAIK, they just don't use it in the example.

Sorry, should have elaborated.  This would be done by using the 
-alias_address option in natd, rather than the -interface option.  man 
natd for more info.


-alias_address | -a address
                  Use address as the aliasing address.  Either this or 
                  -interface option must be used (but not both), if the
                  -proxy_only option is not specified.  The specified 
                  is usually the address assigned to the ``public'' 

                  All data passing out will be rewritten with a source 
                  equal to address.  All data coming in will be checked 
to see
                  if it matches any already-aliased outgoing connection. 
  If it
                  does, the packet is altered accordingly.  If not, all
                  -redirect_port, -redirect_proto and -redirect_address 
                  ments are checked and actioned.  If no other action 
can be
                  made and if -deny_incoming is not specified, the 
packet is
                  delivered to the local machine using the rules 
specified in
                  -target_address option below.

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