qaxf6auux qaxf6auux - 16 days ago 9
Linux Question

ssh: Could not resolve hostname [hostname]: nodename nor servname provided, or not known

I am trying to set up a VPN with a Raspberry Pi, and the first step is gaining the ability to

ssh
into the device from outside my local network. For whatever reason, this is proving to be impossible and I haven't the slightest clue why. When I try to
ssh
into my server with
user@hostname
, I get the error:

ssh: Could not resolve hostname [hostname]: nodename nor servname provided, or not known


However, I can log into the server with,

ssh user@[local IP]


The server is a Raspberry Pi Model B running the latest distribution of Raspbian and the machine I am trying to connect to it with is a Macbook Pro running Mavericks.
ssh
was enabled on the Raspberry Pi when I set up Raspbian.

I have perused Stack Overflow for hours trying to see if anyone else had this problem and I have not found anything. Every
ssh
tutorial I find says that I should just be able to set it up on the remote machine and log in from anywhere using a hostname, and I have never had success with that.

Answer

Recently I came across the same issue. I was able to ssh to my pi on my network, but not from outside my home network.

I had already:

  • installed and tested ssh on my home network.
  • Set a static IP for my pi.
  • Set up a Dynamic DNS service and installed the software on my pi. I referenced these instructions for setting up the static ip, and there are many more instructional resources out there.

Also, I set up port forward on my router for hosting a web site and I had even port forward port 22 to my pi's static IP for ssh, but I left the field blank where you specify the application you are performing the port forwarding for on the router. Anyway, I added 'ssh' into this field and, VOILA! A working ssh connection from anywhere to my pi.

I'll write out my router's port forwarding settings.

(ApplicationTextField)_ssh     (external port)_22     (Internal Port)_22     (Protocal)_Both     (To IP Address)_192.168.1.###     (Enabled)_checkBox

Port forwarding settings can be different for different routers though, so look up directions for your router.

Now, when I am outside of my home network I connect to my pi by typing:

ssh pi@[hostname]

Then I am able to input my password and connect.