How to Get Public IP From LinkSys Router?

[Drew Tomlinson]

I need to get my public IP address from a LinkSys cable router and don't
have any idea where to start.  The LinkSys is doing NAT and my FBSD box
in on the private network on the inside.  What commands and/or ports are
there that would provide the public IP address from the command line so
I pass the IP to a script?  Any ideas?

Thanks,

Drew