I am trying to set up a public SSH server.
[Q1] Can my ISP make this impossible?
[Q2] Does it appear impossible given my situation?
When I go to whatismyip.com it reports: 174.128.21X.XX
When I check the status on my router: 10.250.1X.XX
When I check ipconfig for local (I fixed it to this for port forwarding): 192.168.1.250
[Q3] Does the following sound right?
Since the IP reported by the router is in the Class A range (10.0.0.0 to 10.255.255.255) and the computers IP is in the Class C range (192.168.0.0 to 192.168.255.255) neither can be accessed from the internet and my ISP must have some other router reassigning a private IP to me. Therefore, there is no way for me to host anything on the internet directly.
All of this is, of course, very confusing because if all the units in my building, for example, are known to the internet as being 174.128.21X.XX, then when I request something from a website - how does it know how to contact me?!
I set up a dynamic dns with dyndns.org using the 10.250.1X.XX address and it works great locally - but clearly there must be something else I need to do.
Thank you for answer all 3 of my questions!
Some ISP's block the common ports for residential service. Like ports 21(ftp), 22(sftp/ssh), 80(http), etc.
But, it sounds like you have a business account. Your external address is the 174.128 address. You would need to forward port 22 to the 10.250 router. Then on the 10.250 router forward port 22 again to the 192.168 router...then on that router, forward port 22 to the computer you're wanting to access.
Quite honestly, I'm not sure why there's a 192.168 router in place. The router assigning 10.250 addresses should be all you need company wide.
When you hit a site like whatismyip.com, we look at the IP address that is assigned to you by your ISP only. We don't attempt to find your network IP like the 10.250 or the 192.168.....I don't even know that we're able to find that information actually.