SSH Out Of Router

Technical Support for Routers
1

Hi.
I am trying (via a script) to get the router to connect to an external server via SSH, without success.
Is there anything obvious I need to do to get this to work?

Here is the ssh command.
ssh -T ${PORT:+ -p $PORT}${KEY:+ -i $KEY} “${USER}@${SERVER}”

Yes, I did specify values for the port and server etc.

Thanks,
Glitch

2

There is a parenthesis issue with the variables eg: ${PORT} and ${KEY}

I’m not sure what the + 's are for. So I cannot help there. If you could give more detail as to what your trying to do it would help.

try:

ssh -T -p ${PORT} -i ${KEY} “${USER}@${SERVER}”

3

Does the router has a public IP address? Did you open the SSH port?

4
  1. No (it’s connected to my main router under WISP).
  2. No, (that was partly what I was asking / how do I do that?)

@nopro404 Another way of writing the command is

ssh -T -p $port -i $KEY

5

Yes, but case matters . $port and $PORT are different.

Per the Google best practices for shell scripts constants and environment variables should be uppercase to show their significance.

https://google.github.io/styleguide/shell.xml#Constants_and_Environment_Variable_Names

Variables used for iteration should be lowercase.

All variables should be wrapped in curlies and quoted so expansion works in all cases. This was a bug in the startvpn script causing VPN files with spaces to not work correctly.

If you are SSH’ing OUT of the router to a publicly accessible server you dont need to open a port - only for SSH’ing INTO the router.

6

How does:

port=1111 differ from PORT=1111 and
$port from $PORT ?
It doesn’t as far as I know, so that isn’t the problem!

Regarding the port number, I assumed that was the port I was logging into (since the username and password are for that purpose)?

7

variables are case sensitive:

root@GL-AR300M:~# port=1
root@GL-AR300M:~# PORT=2
root@GL-AR300M:~# echo $port $PORT
1 2

the -i option is for a file name of the public key to use not your password or ‘key’ if that helps.

Regarding the port number, I assumed that was the port I was logging into (since the username and password are for that purpose)?

I’m not sure what this means. 22 is the default ssh port - unless you’r doing something different.

8

I am logging into a remote server so assumed the port I specify is for that (just as when you use a VPN server, it has a port number? eg. 443, 1194 etc.).

9

Yes - SSH servers by default listen on port 22. If it is 22, you don’t need to specify it, it will default to it.

10

Keep in mind that Dropbear (SSH Client/Server) is installed by default… and it, like BusyBox, can behave different…

OpenSSH-Client is in the repo if I recall correctly - which might be helpful if porting scripts from other non-embedded platforms.