Putty How-To

Basic Putty SSH HowTo

Basic Putty SSH HowTo

Table of Contents

  1. Introduction
  2. Prerequisites: What You Need to Have
  3. Download and Install Putty
  4. Set Up a Session
  5. What Now?


SSH is a protocol similar to Telnet in that it allows you to login to a computer from anywhere on the internet. When you login, you get a command prompt from which you can issue the same commands that you would issue if you were actually sitting at the remote computer's physical console.

SSH is different from Telnet because SSH uses strong encryption for privacy and authentication. It is only secure if your password is not guessable.

This is HowTo covers the use of Putty SSH, a particular client program that is well suited to a Windows environment.

Prerequisites: What You Need to Have

Before you begin, you should have a username for your account on the system you want to login to, the DNS hostname of that system, the SSH server key fingerprint, and your password for that system.

In the directions below, the sample values are:

Username: wai
Hostname: mmc34a.resnet.cornell.edu
Server Key Fingerprint: b5:41:21:46:74:ca:f0:e8:b3:e7:1f:3f:55:73:68:bf
Password: ****

You must replace the sample values with your own in the instructions below.

This HowTo also assumes that you have a Windows box and an internet connection that you know how to use.

Download and Install Putty

Installation is really quite trivial. Just download it from ftp://ftp.tartarus.org/pub/people/owen/putty-x86.exe and save it on your desktop (or somewhere else appropriate).

If Putty SSH is no longer available at the link above, try searching for "putty" from Google.

If you have trouble running it once downloaded, be sure you are downloading it in binary format, not in ascii format.

Set Up a Session

Follow these step-by-step instructions to configure a session in putty. A session in putty is sort of like a bookmark in Netscape.

  1. Start Putty by double clicking it.
  2. The GUI should initially show the Session panel. If not, click "Session" under "Category" to display the Session panel.
  3. For "Host Name (or IP address)" enter the hostname of the computer to which you want to connect, "mmc34a.resnet.cornell.edu".
  4. For "Protocol", choose SSH, not Telnet or one of the others.
  5. Under "Saved Sessions" enter "ssh to mmc34a.resnet.cornell.edu", but don't bother clicking the "Save" button yet.
  6. Under "Category" click "Connection" to show the Connection panel.
  7. For "Auto-login username" enter your username, "wai", for the computer you want to connect to.
  8. Click the "Connection"->"SSH" under "Category" to show the SSH panel.
  9. For "Preferred SSH protocol version" choose 2, not 1. SSH2 is a more modern, more secure version of the SSH protocol.
  10. Click "Session" under "Category" to get back to the Session panel.
  11. Click the "Save" button to save your settings for this session. You should now be able to quit by clicking Cancel, restart putty, and still find the session called "ssh to mmc34a.resnet.cornell.edu" under "Saved Sessions".
  12. Double click "ssh to mmc34a.resnet.cornell.edu" to open a session to mmc34a.resnet.cornell.edu.
  13. If this is your first time connecting to mmc34a.resnet.cornell.edu, you will be given a security alert asking whether you recognize its key. This is basically asking you to verify that the key of the host you are logging in to is the correct key. The host's key is proof to you that you are contacting the correct computer, not a rogue server that is impersonating mmc34a.resnet.cornell.edu to steal your password. Check that the key is correct. If it is correct, click "Yes" to continue. Otherwise, click "Cancel" to abandon the session, and alert your system administrator to the fact that the host is being impersonated.
  14. When prompted, enter your password for this account.

You should now get a command prompt on the system you were trying to contact. From here you can run programs, etc.

What Now?

You have now logged into the remote computer or server. Congratulations!

If you are logging in to a Linux system and are new to Linux, you may wish to check out an introductory Linux tutorial.