Official website for Linux User & Developer
FOLLOW US ON:
Dec
28

SSH from a web browser tutorial

by Joey Bernard

There are times when you are stuck using a locked-down machine. As long as you have a browser, though, you can still connect to your remote machines. Here’s how…

SSH is the de facto way of securely connecting to remote machines where you need to get work done. Normally, this is achieved through an SSH client application installed on your desktop. Unfortunately, there are situations where this is just not feasible, for any number of reasons. In this tutorial we will look at a few different options for how to regain a command- line connection to your remote machines.

No matter how locked down a machine may be, you will almost always have a web browser available. We can leverage this and get an SSH connection established through this browser. There are several different technologies that can be used to give us this connection. The first option we will look at is a purely browser-based application that requires nothing extra on either the client side or the server side. Naturally, the available options are limited, but it is one of the leanest options. The issue is that you need to use a supported browser. The second option is a Java-based one. A Java applet is loaded into your browser to handle the actual SSH connection management. Unfortunately, this is only an option if you have Java installed and are allowed to run Java applets in the browser. The third option is even leaner on the client side than the first option, and has the added advantage of running in almost any browser. The downside is that it requires you to install a piece of server-side code to facilitate the actual SSH connection management.

Hopefully, by the end of this tutorial, you will have found an option that fits your situation and helps you manage your remote machines no matter where you are.

There is an URL always available pointing you to a goo.gl URL containing an FAQ for Secure Shell
There is an URL always available pointing you to a goo.gl URL containing an FAQ for Secure Shell

Resources

Secure Shell
Shellinabox
MindTerm
DropPages
Pancake

Step 01 Finding an SSH client plug-in

Both Chrome and Firefox have SSH clients in their respective app stores. In this tutorial, we will be looking at Secure Shell from the Chrome store and FireSSH from the Firefox store.

Step 02 Installation

In the case of both browsers, installation should be straightforward. All you need to do is find the relevant app in the browser store and click on the Install button. Most browsers also require a restart before the SSH client is ready to use.

Step 03 Open a new connection

For the rest of this tutorial, we will use the Chrome version. To open a new connection, simply click on the ‘Secure Shell’ icon on the browser homepage. This will open up a connection window where you can enter the host, username and password.

Step 04 Terminal Options

‘Secure Shell’ in Chrome does not have a terminal preferences window yet, so you need to open a JavaScript console (by clicking the menu item View>Developer>JavaScript Console) and entering the changes you want to make. For example, you can set the background colour with the following: term_.prefs_.set(’background-color’, ’wheat’)

Step 05 Working in SSH

You can do almost everything with ‘Secure Shell’ that you would normally do with a regular client. You can do port forwarding by including the relevant options when you make the original connection. You place these types of options in the SSH Arguments box.

shellinabox
Working in SSH

Step 06 Closing connections

You close your connection the same way you would with any other SSH client, by typing in exit. When the connection closes, ‘Secure Shell’ offers you the option to reconnect (R), choose another connection (C), or simply finish and exit (x). If you choose ‘x’, the current browser window will stay open but will be inactive.

Step 07 Saving connections

All of your previous connections get stored as a list that becomes available at the top of the connection screen. Clicking on one of these stored connections lets you edit the SSH options before firing off and connecting to the remote machine.

Step 08 Finding a Java plug-in client

There is a Java applet that you can use called MindTerm. In this case, you need to wrap MindTerm in a simple webpage in order to get the browser to load it for you and host it somewhere visible. You can also run it directly as a Java app.

Step 09 Installation

If you need to host MindTerm somewhere non-local, you can place it on a hosting service if you have one. If not, you can get a Dropbox account and host it there as a static webpage. There are services like DropPages or Pancake.io that will help you here.

Step 10 Open a new connection

The screenshot above is made using the MindTerm jar file standalone. The behaviour is the same in the browser. When it starts up, it asks you to enter either a server alias or a server hostname. If this is a new machine, it will ask you whether you want to save it as an alias.

Step 11 Connection options

The advantage of a Java applet is that you have more tools available to you. Clicking on the menu item Settings>Terminal… will pop up a full preferences window where you can set the terminal type, font type and size, and colours, among other items.

Connection options
Connection options

Step 12 Working in SSH

With MindTerm, you also have easy access to all of the SSH connection options. Clicking on the menu item Settings>Connection… will pop up a new window where you can set port forwarding, as well as more esoteric items such as the type of cipher or the type of compression to use.

Step 13 Closing connections

You close your session with the exit command, just like with a regular SSH client. Once the connection is shut down, MindTerm resets itself and is ready for a new connection to a new host.

Step 14 Saving connections

Whenever you connect to a new host, MindTerm asks you whether you want to save it in the list of hosts under an optional alias. To get access to these saved connections, you will need to click on the menu item File>Connect…. This will pop up a connection window where you can select the server from a drop-down box.

Step 15 Client/server browser-based SSH

The previous two methods have an advantage where all of the SSH connections are essentially only through the client and the server. This also means that the machine you are working on also needs to allow network connections on the ports that you need, most often port 22. But what can you do if your desktop is locked down to only allowing HTTP traffic? In this case, you need to move the workhorse part of your SSH connection off to another machine, and connect to it over HTTP with your browser. The most common choice for this is shellinabox.

Step 16 Installation

Once you download the source, you need to install it with the usual ./configure; ./make; ./make install step that should be in most Linux users’ repertoire of skills. You do this on the remote host that you want to connect to.

Step 17 Starting the server

Once shellinabox is installed, starting it is done by simply starting up shellinaboxd on the remote host. There are tons of options available as command-line parameters. The most common ones are options like –port=x, and –verbose.

Step 18 Starting the client

To start the client, you simply need to open your browser and enter the URL to the remote machine. It will look like http://mymachine.com:4200, where you might have changed the port being used. This will open up a terminal where you can enter your username and password.

Step 19 Connecting to a different machine

Once you log in, you can always just SSH to another machine. But if this is something that you always do, you can get shellinabox to do this for you by using the option -s /:SSH:mynewhost.com. This means you could have connection tunnels to multiple different machines, each with its own port.

Step 20 Connection options

Because this is the leanest of the web- based SSH clients available, you simply don’t have the same level of configuration options.

Right-clicking in the terminal window will bring up a set of options that get saved in a web cookie that survives over sessions.

Step 21 Working with SSH

Unlike the other methods, you do not have the option to set up more complicated options, like SSH tunnelling. All you get on the client side is pure HTML, with nothing else. If you need more, you will need to use one of the other methods.

Step 22 Closing connections

Like every other SSH client, you shut down your connection with the exit command. This leaves your browser window open with a button popping up in the centre labelled Connect. Clicking on this button will refresh the screen and reopen the connection to your remote host.

Closing connections
Closing connections

Step 23 Saving connections

Unfortunately, there is no real way to ‘store’ a set of connection strings to different machines within shellinabox. The best option open to you is to configure a series of daemons on different ports tunnelling to different machines, and then you can save the URLs to these servers as bookmarks in your browser.

Step 24 Where to now?

Hopefully this tutorial will have shown you some options that are available when you get stuck with an overly locked down machine. If these don’t fit your exact situation, don’t be afraid to look for some of the other options available out in the wild.

Tags: ,
  • Tell a Friend
  • Follow our Twitter to find out about all the latest Linux news, reviews, previews, interviews, features and a whole more.