Are there any built in system commands such as ping that let me discover my public ip-address either on a Windows or Linux operating system? This should not rely on any third party websites or services.
closed as not constructive by Zoredache, Michael Hampton♦, RobM, John Gardeniers, Dave M Feb 5 at 13:20
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To tell what your public ip address appears to be to third parties you need a third party to tell you what they see.
If you don't want to rely on a third party...be the third party and have your own web server located somewhere else tell you.
Even if you can get the information from your router that may not always be what other systems see - you may be behind carrier NAT or an ISP proxy server.
Before the packets reach the NAT device, there's not enough information to determine what the external IP address is going to appear as. To answer your question, I'd log on to the ADSL modem (if that's what is supplying your internet connection and doing the NAT for you) and check the connection and see what IP address was assigned by the ISP.
If my assumptions accurately reflect your network setup, that IP address you see should be the address other hosts on your LAN appear to be when viewed from the Internet.
The config at my workplace is messy and has unnecessary bits... if I do a tracert, I don't see a hop with an IP address that matches what whatismyip.com reports is my IP address.