Frequently Asked Questions
Questions regarding...

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Dialup & PPP

  • How do I log in using PPP?

    All faculty members and Ph.D students who are requested by faculty members, have access to PPP. Send CRF your desired hostname and type of computer you have including type of OS and we will send you information on getting access to PPP.

      Windows 9x, Me, 2000 PPP setup Instructions:
    1. Assuming you have a modem installed and functional, go to Network/Dial-Up Connections, and double-click on "Add New Connection...". 2. Follow the instructions, entering "212-939-7187" as the number to be dialed.

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  • What is the IMAP/POP3/SMTP server?

    Please set your mail server to be: or
    If you have any problems, send email to crf.

    Considering the large number of users we are supporting, please set your check-mail time interval to 5 minutes or above. Thank you.

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  • How do I use 'vacation' program?

    Quick instructions:


    The vacation program creates and initializes files that track who has sent you mail. This means you must run the vacation program. Simply changing your .forward or .procmailrc is not enough.

    The vacation program will create a .forward file for you if one does not exist. If you use procmail to filter your mail, it will create an incorrect one--deleting it should be sufficient.

    procmail users need a recipe to send a copy of each mail to the vacation program.

    Also, vacation may behave differently on solaris and linux. Since all our mail is now delivered on solaris, you must use cluster's vacation program to initialize the vacation system.

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  • How do I use procmail to forward "urgent" messages to my pager or cell phone?

    Put the following lines in your .procmailrc (make sure they precede any other 'recipe' in .procmailrc):

      :0 c
      * ^Subject:.*URGENT.*

    Instruct your correspondents to put the word URGENT in the subject line of their message if they want to reach you this way.

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  • How do I block spam emails?

    Put the following lines in your .procmailrc:

      :0 c
      * ^From:.*somebody@somewhere\.com

    where is the address you want to block.

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  • How do I access Webmail?

    Goto to access your Computer Science email account via the web.

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    File Recovery

  • How can I recover files?

    click here for detailed information.

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  • How do I change my password?

    On Solaris, type: passwd -r nis

    On Linux, type: yppasswd

    Cluster Machines are Solaris

    Clic and Compute Machines are Linux

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  • What should I consider before choosing a password? (What is a good password?)

    Don't use your username as your password.
    Don't use your first name or your last name as your password.
    Try to append numbers to your passowrd you have chosen.
    First letters of a commonly used phrases mixed with numbers.

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  • What software does CRF and where are the instructions for them?

    Please look at the software tools page.

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  • My Web page is not accessible

    There are a few things to check:

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  • My CGI scripts don't work

    Writing CGI scripts is not for the faint of heart. Unlike the above instructions for regular Web pages, the instructions for CGI scripts will be intentionally less "automatic" to make sure you really understand what you are doing. Those scripts have full access to all of your files and you certainly wouldn't want them to do something nasty, would you?

    Still with us? Good. Here are a few things to check:

    Please do all your testing on the backup Web server,, until you are sure your scripts will not do something silly to bog down the server. During this testing, you might find it useful to look at the CGI logs, in /import/http/LOGS.www or /import/http/LOGS.web respectively.

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  • Do we have a secure web site using https?

    Create your files and put them in a directory under ~user/secure_html. Access to the web server is via

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  • How do I restrict access to my website using htpasswd?

    1) cd into the directory you want to password protect:

    $ cd ~/html/protected

    2) Then create a file called .htaccess which contains the following lines:

    AuthUserFile /home/LOGIN_NAME/.htpasswd
    AuthGroupFile /dev/null
    AuthName ByPassword
    AuthType Basic
    require valid-user

    Note: you can use different .htaccess and .htpasswd files for different directories. Just copy the above .htaccess file into another directory and change AuthUserFile path from /home/LOGIN/.htpasswd to the directory where the new .htpasswd file will reside. You have to make this file (.htaccess) world readable. Also, the path to the password file has to be an absolute path, because relative paths will not work.

    2) You need to create a file which contains the list of users and their respective passwords. To do this, login to cluster.cs and type:

    $ htpasswd ~/.htpasswd USERNAME

    You will be prompted for a password for this user. Repeat the above for each user, and when you are finished, make the file, .htpasswd, world readable.
    (Note: It's advised to place this file outside of your /html directory for security reasons.)

    Place the .htaccess file in the directory you want to protect, and that's it. Now, only users listed in your .htpasswd file will be able to access that directory.

    More tricks and tips on htaccess

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    Windows/Unix Problems

  • How do I set up my new computer?

    Send mail to with the following information:

    Then you will receive an ip address and other various information.

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  • Newly installed Windows XP cannot mount Unix filesystems
    From Start->Run, type: \\\username for students, and \\\username for faculty. Please use your account on the WIN-CS domain to mount your home directory. If you have a windows XP desktop on that is part of the WIN-CS domain, you should see your unix home directory appear as the Z: drive.
    We've removed links to download plain-text registry since, for security reasons, we are no longer allowing mounts via samba.

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  • How do I stop Windows 2000 Dynamic DNS?

    Windows 2000 has added support for DHCP clients to update the DNS server with the computer's name. Unfortunately, Windows 2000 will send this update out even if the computer has a static ip address and the DNS server constantly refuses the updates. Since crf does not want these update requests going to our DNS server, Windows 2000 Dynamic DNS should be turned off as follows: To prevent the client from registering name-to-IP address mappings:

    Double-click the Network icon in Control Panel.
    Right-click the icon for the connection on which you want to disable registration of name-to-IP address mappings, and then click Properties.
    Click Internet Protocol (TCP/IP), and then click Properties.
    Click Advanced, and then click the DNS tab.
    Clear the check box Register this connection's address in DNS.

    Or download this registry file and double click: Registry File
    Of course, you'll have to reboot. Please note: the Register this connection's address in DNS checkbox will remain checked, but the DNS updates will be disabled.

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    Misc (Root, Groups)

  • How to add groups and maintain them.

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  • I think I need local root access. What should I do?

    First, you need to think about a few questions.

    1) Am I working for a professor? If not, then you will not get an account.

    2) What do I need to do as root? If the answer to this question is not a never ending answer, then sudo is the option for you (with your professor's approval of course).

    3) The above two questions and answers haven't helped me, what should I do now? First, email your advisor and crf listing the reasons you absolutely NEED a root account, and then we'll get back to you.

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  • I can't send mail from behind a NAT router.
    (An issue with some Linksys products).

    Basically, you need to go into the router config (generally through the web-based admin page) and make sure that the MTU is enabled and set to 1492. See the Linksys page for more details.

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  • My profile disappeared (some of my commands don't work, and the prompt isn't personalized)...

    If a .profile file exists in your home directory, then try typing:

    . ~/.profile

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