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I'm having a hard time connecting to my Ubuntu SSH server. I use Putty for my SSH client. I've run though the usual diagnostics and verified...

  1. OpenSSH is installed on server
  2. Port 22 is open on the server and modem
  3. Port 22 is forwarded to the server
  4. SSH is running
  5. Can connect to SSH server from other devices on LAN with Putty, but not outside
  6. Can ping SSH server from other devices on LAN, but not outside

I can even use "canyouseeme.org" to get...

"Success: I can see your service on $my.external.IP.address on port (22) Your ISP is not blocking port 22"

but... if I slam my external IP address into putty it will just take me to a black screen until the connection times out.

What gives? I can't think of what the issue could be.

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    Are you trying to use "external IP address" when you are actually on the LAN side where server lives? – Alex Jan 21 '17 at 23:23
  • I have a C1100Z ZyXEL acting as modem and router.There is a second router for wifi that is a belkin N450 DB. I have the server hooked into the modem with a static IP that recognizes the modem as the waypoint. The fire wall is off on the belkin router also. I have a rule that forwards port 22 to port 22 on the server. Its not a NAT rule... I'll have to go look at that. ALSO! "canyouseeme.org" seems to check for more than if the ISP is blocking the port. I know this because if I turn the server off and use CanYouSeeMe.com, it reports that it can't see my service and "fails". – TheJakester42 Jan 23 '17 at 7:16
  • I haven't tried to connect to the server from a computer that wasn't connected to the LAN yet. What I've done so far is use the server via ssh from my lap top which is connected to the wifi here. I connected to it using the static IP that the server has on the LAN. After it connects up, thats when I try to put my external IP address into putty. Of course... no dice. Should I try connecting to the server from a computer that isn't on the same LAN? Does that even matter? – TheJakester42 Jan 23 '17 at 7:19
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After it connects up, thats when I try to put my external IP address into putty. Of course... no dice. Should I try connecting to the server from a computer that isn't on the same LAN? Does that even matter?

Yes , it is a huge matter. You can't use external (public IP) address when you are on the LAN(s) side behind primary(ISP) gateway. If your router doesn't support NAT reflection(most consumer grade firewalls doesn't have such feature) then it won't work. Try to connect to your server using putty from "outside" of your local network (home/coffee shop) then it should work and use local (LAN) IP of the server when you are on LAN side.

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The problem is coming from your router, not the server apparently.

"Success: I can see your service on $my.external.IP.address on port (22) Your ISP is not blocking port 22"

This result won't help you much ... Not blocked doesn't mean that a device is listening for data on that port.

What is your router's brand and model ? This way we could help you !

I you know how, try adding a NAT rule that redirects your incoming port 22 connections to the LAN device you want to access (e.g : redirect port 22 to 192.168.0.45)

  • Thanks for the help! I'm not sure how to set up NAT rules. When I go to NAT menu on the modem, all I get is an "enable" and a "disable" option. I was able to set up a rule for port forwarding in the "port-forwarding" menu, is that the same thing? Also! look up in the comments, I left the brand and model of the networking equipment as well as some other info. – TheJakester42 Jan 23 '17 at 7:24
  • Yeah, nat and port forward are almost the same thing ... So if you already forwarded the ssh port to your LAN device, it'd be ok ! – Taz8du29 Jan 24 '17 at 0:10

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