ssh server's hostname help please!

So basically, I am setting up a ssh server for a friend to be used as shared storage between multiple offices and I have done this fine using ubuntu server edition and I'm confident enough with the security side of things.

This server is on the office renting company's network and I can connect to it from PCs within this LAN using its local IP address. However, I'm unsure of how I go about making the server accessible from the internet. I think this must be stupidly obvious but I can't find an answer anywhere. I don't understand how I get a unique hostname for the computer.

And at a more general level, what information is sent in a packet for a web server etc to know which computer it is sending information to in this network?

Thanks for any help

 

any help guys? Really need a quick answer to this! Cheers

 

You need the public IP (visit whatsmyip) and maybe some forwarding on the router.
I'd get a router with Dynamic DNS built in... but a Linksys with dd-wrt could do this & even a vpn, ssl server.