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Password overview

At SCS, as outlined below, you may have passwords for several different uses. Note that, for security reasons, you should keep your primary SCS Kerberos password unique. If you forget yours, see our page on getting a password reset

On this page:

  • Your "main" SCS Kerberos username and password
  • Kerberos "instances," including:
    • username/mail
    • username/remote
    • username/root
    Each Kerberos instance has it's own, unique password.
  • Your SCS Windows domain username and password
  • Local Unix passwords on specific Unix hosts

SCS Kerberos username & passwords

How to get one: Your main SCS Kerberos username and password are created as part of the SCS user-account creation process. Download and fill out an SCS account application [.pdf format], have your sponsor sign it, and return it to the Help Desk, GHC 4203.

When to use it: Use your main SCS Kerberos username and password when:

  • Logging on to a Linux computer running an SCS supported computing environment, including linux.gp.cs.cmu.edu
  • Obtaining Kerberos tickets using kinit
  • When logging in to MRM

How to change it: You can either use the Instance Manager Tool or run the kpasswd command on a Linux computer running an SCS supported computing environment to change your main Kerberos password.

Kerberos instances & passwords

"Instances" can be considered named "children" of your main Kerberos identity, and each has its own password.
Note: The primary SCS interface for managing Kerberos instances is the interactive, Web-based instance manager. SCS Computing Facilities encourages using this tool or you can run remctl on any Linux computer running an SCS supported computing environment.

How to get one: You can use the Instance Manager Tool to create instances yourself.

When to use it: Below is an overview of common Kerberos instances and their purposes:

/mailThis password is used exclusively with your SCS IMAP email. This password is not created for you initially.
/remoteUse this password to authenticate to VPN and iPass
/rootThis is a special Kerberos instance for people who need to do advanced system administration on Linux machines running an SCS supported computing environment.

You may have additional instances with specialized uses, as described in the Kerberos documentation.

How to change an instance password: You can either use the Instance Manager or run the command: kpasswd <username>/<instance> on a Linux machine running an SCS supported computing environment. (for example: kpasswd example/mail) to change Kerberos instance passwords.

Note that if you forget the password for your mail or ftp instances, you can use the Instance Manager to change these passwords as long as you know your main SCS Kerberos password.

SCS Windows domain username & password

How to get one: The SCS Windows domain username and password are normally created when we process your SCS user account application.

When to use it:

  • When logging in to Windows computers in the SCS Windows domain
  • When connecting to pc_dist or mac_dist on monolith.scs.ad.cs.cmu.edu
  • When accessing your your SCS Exchange email account
Even if you do not use a Windows computer regularly, you may still have an SCS Windows account. Please contact the SCS Help Desk to confirm whether you have an SCS Windows account.

How to change the password: You can either use the Instance Manager Tool at https://webiso.cs.cmu.edu/instance or once logged into a Windows host using the current password, enter: CTRL-ALT-DELETE [simultaneous key-chord] to bring up a dialogue box with the "Change Password..." button.

Local Unix passwords

How to get one: On a Linux host running an SCS supported computing environment to initially set a local password, you must be logged in as root. You can then run the command:

     passwd [Username]

to create a local password for the User indicated. Once a local password has been established for a User then that User can change their local password simply by running the passwd command.

To remove a local password the /etc/passwd and /etc/shadow files must be edited by hand. You will need local root access to do this. If you need assisitance with such an operation send email to help@cs.cmu.edu. Once this is done you will then need to use your SCS Kerberos password to login.

When to use it: Some Unix applications, for example, xlock and some graphical display managers, don't understand Kerberos and expect a local password. A local password also allows one to login to hosts that are off the network and thus can't talk to the Kerberos servers.

How to change your local Unix password: See "How to get one" in this section.

Related documentation

Kerberos in SCS
About Kerberos in SCS.
How to choose good passwords
How to choose good passwords that can be remembered.
Encryption & password security
How to protect your passwords from being eavesdropped from the network.
Windows passwords
Additional information on Windows passwords