[Dshield] How do I determine NAT address

Chris Brenton cbrenton at chrisbrenton.org
Fri Mar 18 11:08:31 GMT 2005


On Thu, 2005-03-17 at 10:51, Chris Mitchell wrote:
>
> I have a need to determine a local IP address when a user logs in to a
> secured portion of my web site.  The external IP is showed in the logs but I
> need to know if I can determine the local address behind the firewall. 

Depends. You will not be able to extract this information consistently
from your logs. You have NAT devices like iptables out there that only
change the source IP, so there is little fingerprint to work with.

So what you really want to do is execute something on the users system
that extracts the information locally, and then transmits it to the
server as part of the HTTP request.  

HTH,
Chris





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