Using PuTTY to Access a Remote Host (SSH Part 2)

13 Mar, 2007 SSH

PuTTY is an invaluable tool that I use nearly every day at work. The two main functions I use if for is telnetting into Cisco devices and secure shell access to remote Linux servers. It allows for the storing of host session information for easy recall. Another advantage is that it is a single executable file which makes it extremely portable. Just toss it on a memory stick and carry it with you in your pocket. The best part is that it’s free!

In this tutorial we’re going to keep it pretty basic. We’ll cover creating and saving a connection session and connecting to a remote host via SSH. I won’t go into the detail of downloading PuTTY because it is out of the scope of this tutorial. However, the official website of PuTTY is http://www.chiark.greenend.org.uk/~sgtatham/putty/. An appropriate version of PuTTY for your operating system can be easily downloaded there. This tutorial will example using PuTTY on Windows XP.

After downloading PuTTY, launch the executable and you will be presented with a configuration window. On the left side of the window you will notice all the configuration items that control things such as terminal emulation, appearance, and connection settings. I’m not going to explain all the features, we’re here to get connected and start working. Make sure that “Session” is selected on the left. On the right will display a form where you will be able to input remote host connection properties. Notice that SSH is the default connection method.

Let’s start by entering the IP or host name of a server that has an SSH server running on it. If you followed part 1, Installing OpenSSH on Ubuntu Linux, then you can use the IP address of your server from that tutorial. The IP address of my server is 192.168.200.10, so I’ll use that. Make sure that SSH is selected as the connection type and 22 is the port.

In the area below you can type a friendly name for your session. This will allow you to easily reconnect to future sessions by having PuTTY recall the connection information.

After typing in a name, click the “Save” button.

You will see the name appear in the list of saved sessions. If future uses, all you will have to do is double-click the name and it will automatically connect you with your remote host.

Now that we’ve saved our session click “Open” to initiate the connection process. Also, take note that the “Close window on exit:” option is set to “Only on clean exit.” This controls how PuTTY responds when you logout or exit your session.

When we connect via SSH to a remote host for the first time a security alerts us of a new server fingerprint. This is one of the ways that PuTTY alerts us when we are or aren’t talking to the server we intend to talk to. If this security alert ever pops up after the initial alert it may mean that the finger print has changed. One cause of this would be a man-in-the-middle attack.

In this case, we are connecting for the first time so we can click Yes.

We are now prompted to login. Notice how this looks strangely like a login prompt that you would see if you were sitting at a Linux console. Enter your username for the remote host.

Now enter your password.

If everything goes as expected, you will see want looks exactly like the command prompt for your remote host. That’s because it’s exactly the case. It is just as if you are logged on to the console directly.

We can issue any commands and see the results. For example, here is a directory listing of the root directory. Notice how PuTTY gives us purty color coordinated results.

That’s all for this basic tutorial. Just as in a local console session, the “exit” command will log you out. If we logout cleanly, the PuTTY window should close as well.