"inside" or "outside" firewall tests?

Does it make any difference if I test my firewall from the "inside" (the local lan side) of my firewall, as opposed to testing from the "outside" internet side?

If I go to a friends house, and use for example "nmap" to test the ISP assigned IP of my home firewall, will I see the same results if I test my firewall while using my PC in my house on the local lan side of my firewall?

Thanks,
Mike

P.S. I guess instead of "inside" or "outside", I could use "in-hose" or "out-house"

 

The inside interface of a firewall is often seen as the trusted network interface, the outside as untrusted. The Soho class Firewalls (nat-routers) usually allow all outbound traffic and block all incoming. So there will be a difference in findings.
Personal firewalls also allow outbound traffic (unless the application/process control decides to block, but that's not a real firewall function).
So, in order to test your firewall, scan from the outside.

 

I would of *guessed* that also.

Now for the question I really wanted to ask: Is there a test site I can go to that will allow me to input MY ISP assigned IP?

I realize that that would allow the entire planet to scan any IP they wanted!

Does such a test site provide some sort of method to prove the IP is MINE?

I'm guessing going to a friends house and using "nmap" would probably be the best?

Mike

 

Your guesses seem right. There are sites that allow you to scan from your own pc (grc.com, pcflank.com, sygate) and depending on the technique they use, you might get the results of your firewall.

There are commercial sites that allow scripted tests, outpost24.com (NOT outpostfirewall!!!) has such a service that you can even tune for your system. They will require you to sign a contract, because liability is a problem!
There are some nice scanning appliances, have a look at QualysGuard Consultant, nice to carry that around (price might be a bit steep for personal use)
And there wil certainly be some hackers sites that allows you to do so, but I am not aware of any site.

Using someones help is the best option. Be ware of the tools you use. I ran such a script on my lan once and it almost killed a server...