How do I find out if I am behind a firewall?

Question

OK, so I live in an apartment that offers me internet, but I have no idea through who, or what type. I have all of my computers running through my router, that is plugged into the Ethernet port in my wall. I would like to run a web server, but am unsure if I have a public ip available to me.

I can access my server from within the network at 192.168.2.5 . I forwarded the port through my router, but if I try to access it through my public ip, the connection times out.

The only information I could find on my router's (belkin) configuration is that the WAN IP it reports is the same as my public ip. I am unsure if I am not connecting because I have configured things wrong, or because I am behind another firewall I can't access. Is there any way to discover additional levels of firewalls between me and the internet?

Answer 1

if the router is reporting your WAN ip as your public IP then you have a public IP assigned to you.

If you want to know who the provider is you can do a lookup as to who the owner is ARIN's lookup site if you are in the US.

As far as if you are behind a firewall - that will be more difficult since even if you did something like an nmap scan your belkin would probably drop the packets anyway.

You should also note that running servers is against every TOS i've seen on consumer level internet connections, and some providers (Verizon i'm looking at you) will filter common server ports (25, 80, 443, 110, etc)

Honestly if you want to run a web server the least headache would be to shell out the 10$ or so a month for a hosted website.

Answer 2

As Zypher said your router should report the IP on the WAN link. If you go to http://www.whatismyip.com/ it will display your public IP address. If that IP address doesn't match the IP on the routers WAN link then there's another router between you and the internet.

Answer 3

A simple way to determine whether you've got the ports forwarded correctly is to take the belkin out of the equation for testing purposes:

1. Un-plug your computer and from your home network
2. Change your computer's IP address from 192.168.1.5 to your WAN IP address
3. Un-plug your router from the modem
4. Plug your computer in DIRECTLY into your modem instead of going through your router
5. Test. You know how to make it work at 192.168.1.5, so it should work the same way on the public internet.

Keep in mind that it's a REALLY BAD IDEA to leave your PC plugged directly into the internet. Bots (from the internet) will be scanning your computer and trying to install viruses. But as long as you aren't connected for more than a couple minutes, and are using a desktop firewall software of some sort, I feel this method really should be OK to test to find out if the Belkin configuration is the problem, or if you really are being "firewalled" by your ISP.

Best of luck!