[standards-jig] Re: My IP Address

Matthias Wimmer m at tthias.net
Tue Sep 2 18:13:29 UTC 2003

Hi Richard!

Richard Dobson schrieb am 2003-09-02 18:33:08:
> Yea I agree that the IP address itself is not all that useful when behind a
> NAT since you will probably not be able to use it for anything, although it
> is useful if you are just trying to automatically find out if you are behind
> a NAT by comparing that IP with the known IP's of your interfaces, i.e. if
> the external IP does not match one of your interface IP's then there you are
> likely behind a NAT.

If your IP is in one of the following subnets you can expect that you
are NATed:, or for RFC 1918 address space
or for link local addresses

If your IP is different from these networks you can expect that you are
not NATed and that the server will respond with the same IP address. But
that does not help you very much as you don't know if there is a
non-NAT firewall.

Just from knowing if you are behind a NAT router you do not know which
file transfers will work for you.

Tot kijk

More information about the Standards mailing list