RSOD: A KISS Reverse SSH web-based tool

November 19, 2008 by Amr

From time to time we need to connect to servers on our customer's network. Ideally, we would just SSH and do our thing; However, few customers are behind NAT meaning we cannot connect to them in a simple manner. The job isn't worth going over the hassle of finding how to bridge the 2 networks together.

Fortunately, SSH provides a solution: Reverse SSH Tunnel. However, it's not very easy for less technical people to do thus, becoming impractical in our case. I thought what we needed was a way to make it trivial to open and close Reverse SSH Tunnels. I googled but I didn't find something that's web-based and is actually usable.

I thought this was a good excuse to hack away and I couldn't resist.

I created RSOD as an idea proof. It's is a very small and relatively self-contained web-based application which sits on a server and allows people accessing its web interface to manage Reverse SSH Tunnels.

From a less technical person's point of view (which is the whole point of RSOD), you send him or her a file by e-mail, for example. They open RSOD, feed it the file and a tunnel has been created for you. Few hours later, you are done, they open RSOD and close the tunnel by clicking the "Close" button.

It currently requires that SSH Keys are used for authentication (or other passwordless mechanism) and subsequently your machine must authorize the public key of customer's machine. That's not a big problem because it's done only once as part of the installation. Password-based authentication could also be possible. Security will mean that the password cannot be passed in the RSOD file which you e-mail to the customer, so this one bit will have to be communicated by some other mean.

You can download the current idea-proof, but working, version from the RSOD Project hosted at github.com.

Hack away.

Permalink