Getting Started with Putty

Table of Contents

What does Putty do?

Putty is a free program that lets you use your PC to make a Telnet or SSH connection to a Unix-based computer. At Boston University you are most likely to use Putty to make a connection to ACS or another computer system so you can use Unix-based programs (such as the mail program, Pine) or Unix print commands

If you plan to use Putty primarily for email, please note that there are many ways to read email that you may find more intuitive. Please see our information about your email alternatives at Boston University .

Technically, Putty should be written as “PuTTY” (it’s a geeky pun), but we will refer to it as “Putty” in this document.

How do I decide between SSH and Telnet?

Putty lets you make your connection using either SSH protocol or Telnet protocol. From your computer, these connections look identical, but because SSH uses an encrypted connection that is more secure than Telnet, we recommend that you always use an SSH connection when connecting to a computer system that supports SSH. BU computer systems, including ACS, support SSH.

Where do I get Putty?

You can download it directly from

Okay, I’ve installed Putty. Now how do I access my ACS account?

  1. Double-click on the Putty icon on your desktop, or go to Start->Programs->Putty.
    putty icon
  2. If a box appears asking if you want to run putty, select Run.
    putty security warning
  3. The PuTTY Configuration box should now appear. Under Host Name (or IP address) enter:
    putty host name
  4. Ensure that the SSH button is selected.
    putty ssh
  5. Select the Open button.
    putty open
  6. The PuTTY terminal will now appear. Enter in your BU login name.
    putty terminal
  7. Now, enter you Kerberos password.
    putty passwordYou have now accessed your ACS account using PuTTY.
  8. If you see some sessions already listed in the lower part of the Putty configuration window, then you have a pre-configured version of PUTTY or you have previously saved some sessions. Simply click on one of the sessions to connect to ACS. In the example below, we chose Then click the Load button.

  9. You will see that the host name and protocol have now been filled in for you. Note that the protocol chosen is SSH, which we recommend for any system that supports it. You could make some settings changes in the left panel if you wanted, but for now, just click Open.
  10. If this is the first time you have connected to this host from your computer, you may see a message like the one below. If you are connecting to one of the ACS computers, you can be fairly confident that nothing fishy is going on, so click Yes. If you are connecting to an unknown computer, use your best judgment.
  11. You will now see a prompt that says “Login as”.  Login as you did in steps 6 and 7 above.
  12. If your login name and password are correct, you will now be logged in. If you are logging on to ACS, you should now see a message that says “Welcome to the ACS Cluster”. You may be prompted to read messages, and you can answer y for yes, n for no or q to quit.

Now you can go about your business on ACS (or other remote computer). When you are ready to quit, type exit and your session will end.

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What if I want to make changes to Putty’s configuration?

Perhaps you don’t like the font size that Putty is using, or some other aspect of its configuration. When you have loaded a session but have not opened it (so you are between Step 2 and Step 3 above), just click on a category on the left side of the screen and make the change on the right side of the screen.

For example, to make a change in the font size you’d go to the left side of the screen and click on Appearance, then click on the Change button on the right and make your font size change.

After you have made your change, click back on Session, at the top of the left panel. You can now click on the Save button if you want to make the change permanent. Then continue to open your session as usual.

Where are the menus?

After you open a Putty terminal session, there are no menus at the top of your screen. To get a menu, right-click (click with your right mouse button) on the session’s title bar, as below. You will get a pop-up menu and can choose the command you want. You’ll see that there is a Change Settings button here, too, so that’s another way to change settings such as font size.

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Strange things happen when I right-click – why?

As we saw above, you can right-click on the title bar to get a menu. If you right-click anywhere else in your window, text may appear your screen. That’s because Putty lets you use your left and right mouse buttons as shortcuts for copying and pasting text. If you use your left mouse button to drag over (highlight) any text in your Putty window, that text is automatically copied to the Windows clipboard. Then, the next time you press the right mouse button inside the Putty window, the text is pasted into the window. This shortcut can be quite useful — once you figure out what is going on.

My host supports SSH1 and not SSH2. How do I tell Putty that?

SSH options are found under the Connection-SSH item on the left side of your screen. Click on SSH, then choose protocol version 1 or 2, depending on which your host uses (ACS supports both). You may need to ask your system administrator about the SSH settings your host prefers.

For more information.

The Putty download site at includes detailed documentation.

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