SSH Tunneling Suddenly Not Working

Question

I have a home PC running Ubuntu 12.10.

In order to make sure that my data isn't being monitored in public, I had in the past used a subscription VPN service.

I decided to research alternatives and I found out that OpenSSH makes it fairly easy to create a SOCKS proxy which can be used with Firefox and PuTTy.

After much trial and error, I finally have a server that I can connect to remotely and use BASH commands in. (I had to use port 80 for the SSH server as a lot of the places blocked traffic through the "usual ports" such as 22.)

The real issue came when I tried to use this as a proxy.

I used PuTTy and went to the SSH Tunnels section and added a Dynamic Forwarded Port and set the port to 80. I then went into Firefox and selected SOCKS v5, 127.0.0.1 as the IP Address, and the port as 80. This seemed to work perfectly and a "whats my ip" Google query returned the correct home IP address -- but then it stopped working.

The shell itself continued to work and I used it to reset the home SSH server to no avail. I have absolutely no clue what it is going wrong and any assistance will be greatly appreciated.

If you need any further information I will be happy to provide it.

Answer 1

I had a similar issue when I tunneled using ssh in GNU/Linux. I don't know if it's related, but in the end the effect is the same, I couldn't find any answers on the net and this was the top search result so I decided to contribute with my solution.

In my case I was running this:

ssh -C2qTnN -D 127.0.0.1:3128 [email protected]

to open a SOCKS tunnel proxy and the command was in a bash script.

The issue and solution: I made the tunnel using one Linux user and its ssh keys and I was trying to connect using another user. The ssh command ran in the background so I couldn't see that it was asking me for authentication. Appending the new local user's public key from ~/.ssh/id_rsa.pub to the remote server in /home/user/.ssh/authorized_keys did the trick.

Note: The authorized_keys file from the remote server should be read-only on some systems, so if you create that file yourself do a chmod 400 authorized_keys because some ssh server configurations will refuse to read it if anyone has write permissions.