Login Service Frequently Asked Questions

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How do I find the IP addresses or the names of the various machines?

The Pool may change for any number of reasons; for example, machines may be rotated out for maintenance. To discover the IP addresses of the Login machines any given time, use the host command:
host login.itd.umich.edu

To discover a machine's name, use the host command with an IP address argument, as shown below:
host 141.211.2.210 (replacing the IP number with the known IP number)

What operating system are the login machines running?

The Login machines run a custom build of Linux, based on Linux From Scratch called UMCE Linux.

What software is installed on the ITS Login Service?

A wide variety of software is accessible on the Login Pool under the /usr/bin directory.

Are there alternatives to the login service?

The alternatives to using the login machines are:

  1. getting access to the CAEN machines in the Duderstadt Center site by getting a joint ITS/CAEN account from the CAEN Office in the Duderstadt Center, or

  2. in a few cases, getting an account on a departmental machine.

Check with the IT staff of the department where you wish to get access.

Are there limits to how I can use the software?

Because the software is supported only in its system-wide configuration, ITS (4-HELP) cannot assist you if you have problems using it in any way other than in its system-wide configuration. You are free to use it in any way that you like, however.

How do I send in suggestions for software?

Email the Login administrators at itcs-login-admin@umich.edu.

Specific Login Commands

How do I change my password?

Use the passwd uniqname (where uniqname is your uniqname) command from the % prompt. It will ask you for your old password, and then your new one twice. The kpasswd command will also work to change your password.

How do I change my full name?

To change your full name, contact IFS-support@umich.edu.

How can I use tcsh as my shell?

Add these lines to the end of your .login file:

if ( $SHELL == "/bin/csh" ) then
        foreach i ($path)
                  if ( -x $i/tcsh ) then
                          setenv SHELL $i/tcsh
                          set shell=$i/tcsh
                          exec $i/tcsh -l
                  endif
        end
endif          

This sets the shell to tcsh if (and only if) it can find a copy of tcsh on the machine. If you really need tcsh to be the login shell, then you should start it with the -l flag as it is done above.

How do I get the standard configuration back?
  • If your account has somehow been misconfigured, you can get back the standard configuration with the command:
    /usr/bin/redot

  • If you only need a specific configuration file, you can limit it to that file by specifying the file on the command line:
    /usr/bin/redot .cshrc

This is usually necessary because someone deleted the files by mistake, or because someone has old files and they need to be updated. The files affected are: .cshrc, .login, .logout, .xsession, .Xresources, .mwmrc, .principals, .profile, .tvtwmrc, .twmrc, .zephyr.subs, .zephyr.vars, and AppleVolumes.

How do I transfer files to and from the Login Pool?

The best way is to use SFTP ("secure ftp"), a feature of SSH. GUI clients are available for Mac OS X and Windows.

You can use Fetch or Fugu (on the Mac) or WinSCP (on a Windows machine); these are downloadable from the Blue Disc website. Connect these to sftp.itd.umich.edu, using your uniqname as login, and your password as password.

How do I change my default editor from pico to vi?

Add the following line to the end of your .login file:
setenv EDITOR vi

How can I keep the login intro message from showing up?

If you don't want to see the daily message, which informs you of changes and important announcements, disable it with a file in your home directory called ".hushlogin". You can create this file with the command:
touch ~/.hushlogin

If you want to re-enable the message, just remove the file with the command:
rm ~/.hushlogin

How can I make a screen with more than 24 lines?

Create a script in a bin directory:

  • Make a bin directory if you don't have one: mkdir ~/bin

  • Edit a file called ~/bin/rs, and add the following lines:
    #!/bin/csh
    eval `resize`
    (Note: use back-quotes, not apostrophes. The back-quote key can often be found beneath the Esc key at the top left corner of keyboards.)

  • Change the permissions on the file to make it executable with the command:
    chmod 700 ~/bin/rs

  • When you have the wrong screen size, type rs and the screen will resize.

  • You can also accomplish the same thing by adding this line to the end of your .cshrc file:
    alias rs eval `resize`

How can I find my recent logins?

At the prompt, type the command "last" followed by your uniqname:

% last <uniqname>

You will see a list of all your logins on the current machine within the past week.

Why can't I use SSH RSA authentication to log in?

RSA Authentication is disabled on the Login Pool's SSH daemon for two reasons:

  1. The Login Pool uses Kerberos, a software package for centralized identification, authentication and authorization. Kerberos is the university standard for authentication.

  2. A user logged in via SSH RSA authentication would still need to authenticate via Kerberos in order to access his/her home directory. Some supported programs will not behave properly if the user's home directory is inaccessible.

How do I find out how much AFS space I've used?

Do this with a simple command:
fs lq

You will get a readout like this:

% fs lq ~uniqname

% fs lq ~bjensen
Volume Name          Quota    Used    % Used   Partition 
user.bjensen       10485764   6019661    57%         81%

This means that bjensen's quota is 10,485,764K, and they are using 6,019,661K, or 57% of that. On the disk where his home directory resides, 81% of the space is being used.

X and the Login Service

What is the DISPLAY variable?

The DISPLAY variable is the variable every X program checks to see where to send the information it is going to display. If you log in to the console on pita.gpcc.itd.umich.edu at the Angell Hall Computing Site, and run xterm on login.itd.umich.edu, then you should have the DISPLAY variable (in the session you are running xterm from) set to biscuit:0. You can do that with the command:
setenv DISPLAY pita:0

This will tell the login.itd.umich.edu machine that you want windows displayed on pita, using display number 0, which is the only display pita has. You also need to set it up so that pita will accept display data from login.itd.umich.edu. To do this, you need to type more commands. Open a new shell on pita, and type this command:
xauth extract .Xauth pita:0

Then go back to the shell on login.itd.umich.edu, and type the following command:
xauth merge .Xauth

There is a method of X "security" using the xhost command, but that method is easily subject to snooping, so it is not recommended.

How can I display Xterms, SPSS windows, etc, on my PC?

Follow these steps:

  • First, set up an X server on your PC. Many people are using Exceed for Windows to do this. Campus Computing Sites now supports Xming as well.

  1. Set your DISPLAY variable (see above question) to your desktop PC. The command should look something like this:

    setenv DISPLAY your.machine.here.umich.edu:0

  2. Include in this command your machine's name or IP number in it before the colon (:). If you don't know what your machine name is, use this command:

    who | grep uniqname (replacing the word "uniqname" with your uniqname)

    Type that command with your uniqname instead of the word "uniqname," and your machine's name will be in parentheses. (If all that's there is a series of numbers, they will work as well.)

  3. Consult your software's documentation to figure out how to allow the machine you are logged into to open Windows on your desktop machine.

  4. Run an X application. If you need help, call 734-764-4357 (4-HELP), e-mail 4HELP@umich.edu, talk to your departmental network admin, or contact login.admin@umich.edu.

Are there security concerns with X?

Yes. Data sent over an X connection isn't encrypted in any special way, so typing your password into an X window that's running on a different machine can allow someone to break your password. Use xauth to minimize this danger. Using xhost or X from your PC is more dangerous, because neither does the encryption and decryption that xauth does. Change your password fairly often to minimize your risk.

Note that you can use SSH to encrypt your X traffic. This highly desirable and is well supported by most SSH clients.