RE: Slick way to upload dynamic IP addresses

[dws]

This approach has one significant shortcoming. If the PC is behind some NAT box (say, a corporate firewall or a LinkSys Broadband Router), then the IP address of the PC isn't particularly interesting to the outside world, since the outside world won't be able to connect to the PC using that IP address.

I have DSL into a LinkSys router/hub, and have the DMZ host set to the local IP address of a Linux box. (Incoming socket connections get routed to the DMZ host, after the IP address gets translated from the router's externally visible IP address to the 192.168.1.* internal address specified for the DMZ host.)

A cron job on the Linux box periodically makes an "I'm alive" HTTP request to a CGI on my ISP. The CGI captures REMOTE_ADDR, which is the externally visible IP address for the router (and the Linux box, since it's the DMZ host.)

Invoking the same CGI with no parameters products a short page of HTML listing the last-known IP address for my home router/Linux box, along with a note about how recent the address is. I hit the CGI from work, open a secure shell connection to my home box, and can IRC from there.

[Anonymous Monk]

Remember: This isn't meant to be run from behind the NAT box. You are right: No one cares if the local machines IP is 192.168.0.1. all that matters is the outside IP address. So, you have it run _on_ your NAT box (like I do) and foreward any necessary packets into the internal network. I currently have windows 2000 forewarding SSH, SSH2, FTP, and Telnet requests(ports 22,22,21, and 23, respectively) to my linux box on the internal network. So I, like you, can do the same things. I can SSH, telnet, or FTP into my computers from far away. However, many people won't buy DSL Routers- they will have 486's routing packets running a light distro of linux- and then this comes in handy. Especially when you are likely to be disconnected frequently- as I am.