SSH into Linux machine over internet

I recently setup a Linux machine in my dorm and I would like to be able to access it via SSH. I'm on a college campus that has several subnets to manage the machines connected wirelessly to the network. Because of this, the subnet of the machines and their IP changes frequently.

Since the machines will likely be on different subnets, I can't SSH by entering the IP address. Is there any way to set up SSH via an internet service or something similar that would forward me to my machine?

You can use Log me in Hamachi.

I use it on a Linux server thats behind NAT with no way of forwarding ports. It's free as in beer.

You setup a network on logmein.com then install the client on the server. This will create a ham0 network device with an IP that will never change. You need to connect your client machines to the same hamachi network and you can ssh to your box by it's hamachi ip.

I think you can use no-ip.com or dyndns.com.

This question may have your answer ddclient updating to local IP instead of public IP

You don't specify if you need to access from the subnet or internet. So the solution is different (both explained in the superuser.com link)