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IT Support

Linux Accounts

All students who are School of Computing majors or are enrolled in SoC courses are authorized to use any of the departmental public workstations.

Passwords

You must use your Clemson password to login to the School of Computing Linux systems. If you wish to change your password, please visit the password change utility. If you have forgotten your password, please visit the CCIT Help Desk (see the CCIT website for details).

Default Shell

Your default shell is the shell that is run by default when you open a terminal or SSH connection. The two default shells that we support are tcsh and bash. Please contact us if you would like to change your default shell.

Home Directory: SSH Key Pair

In many cases (like using a remote VCS server) it will be necessary to generate an SSH key pair using the ssh-keygen command. Log into an SoC lab workstation and follow the steps below to generate an SSH key pair in your home directory. You will be prompted for the location to store the key pair; just hit enter to accept the default location in your home directory. You will also be prompted to enter an optional passphrase. SSH keys are inherently more secure than password authentication, but using a passphrase adds another layer of security. If you choose to use a passphrase you will always be prompted for the passphrase. There is no way to recover the passphrase if it is forgotten.

username@labmachine:~$ ssh-keygen -t rsa -b 4096
Generating public/private rsa key pair.
Enter file in which to save the key (/home/username/.ssh/id_rsa):
Created directory '/home/username/.ssh'.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/username/.ssh/id_rsa.
Your public key has been saved in /home/username/.ssh/id_rsa.pub.
The key fingerprint is:
4b:de:82:26:ed:be:2f:b0:f2:00:a7:31:2d:4f:fc:55 username@labmachine
The key's randomart image is:
+--[ RSA 4096]----+
|                 |
|                 |
|        E        |
| o     .         |
|= =   . S        |
| X ..o + o       |
|. o oo+ + .      |
|  ...+.  .       |
|   o..++.        |
+-----------------+

You will now have a .ssh folder your home directory containing the private and public key files. The public key id_rsa.pub can now be used for SSH public key authentication.

Home Directory: Quota

You are given a limited amount of storage space (quota) in your home directory. Depending on what your current status is (major, student or faculty/staff) you will have a different amount of space. To find out what your quota is currently set to, use the fsquota utility like this:

# fsquota -s ~
Disk quotas for user pkilgo (uid 224577): 
     Filesystem   space   quota   limit   grace   files   quota   limit   grace
   /home/pkilgo   8343M  15360M  17408M            156k    450k    500k

If you need a larger quota, feel free to ask. Quotas are there to prevent any one person from filling up the file system and ruining everybody's day. We will normally grant modest quota increases if they are necessary for instructional or research purposes.

The fsquota utility is actually an easier-to-use wrapper around the quota utility. Have a look at man quota if you'd like to learn about its more advanced usage.

Home Directory: Snapshots

A.K.A. Help! I've deleted or goobered up a file and I want it restored!

We take periodic snapshots of the contents of your home directory and keep them for a limited time. What this means for you is that you may be able to recover some or all of your files in the event that they are accidentally removed or overwritten.

You can access these snapshots by entering the directory ~/.snapshot. Within that directory are named snapshots - each is a directory that is a snapshot of your entire home directory as of the time that the snapshot was taken. You may interact with the files within these directories just as you would with normal files, with the exception that the snapshot data may not be modified. To modify the data within a snapshot, you must first copy the data to your home directory or another file system, then modify the data there.

Home Directory: Accessing from personal computers

Due to security limitations of the NFS protocol, we cannot allow anybody to directly mount their home directory via NFS on their personal computers, or any computer to which they have administrative control. If you need to access your home directory from your personal computer you do have a few options:

  • SFTP: Use a tool like WinSCP (Windows) or Cyberduck (MacOS) to connect to any of our systems using SFTP (Secure File Transfer Protocol). These tools provide an easy drag-and-drop interface to move files between your personal computer and your SoC home directory.
  • SSHFS: The SSH File System can be used on Linux or Mac systems when you need POSIX-like file access semantics directly to your home directory. Please contact us if you need help setting this up.
  • CIFS (a.k.a. Windows File Sharing or Samba): Most home directories are also available through the CIFS protocol. Please contact us if you are interested in figuring out how this works.

Web Development Space

All School of Computing users have web development space available to them at webapp.cs.clemson.edu. When logging in the first time, a home directory will be provisioned on the server at /home/$USER where $USER is your Clemson username. This directory is local only to the webapp server and is NOT linked to your School of Computing network home directory. We recommend using SFTP to backup content here to your SoC home directory or using a remote version control system (VCS), such as one provided by the School of Computing at buffet.cs.clemson.edu. When using a remote VCS you will need to follow the instructions above to generate an SSH key pair to enable SSH public key authentication on the remote server.

username@ada1:~ [1] ssh webapp.cs.clemson.edu
username@webapp's password:
Creating directory '/home/username'.
.
.
.
username@webapp:~$ ls
public_html

Anything placed in the public_html directory within the /home/$USER directory will be available at http://webapp.cs.clemson.edu/~$USER. Please note that this server is only accessible from within the campus network. Content hosted here is not visible on the internet. If off-campus, connect to the campus VPN to be able to view content on this server.

The web server is PHP-enabled as well, so you may host your scripts there. There are a couple of caveats you should be aware of:

  • PHP files just need to be readable by you, or chmod u+r, in order for the web server to read them.
  • All other files need to be readable by everyone, or chmod o+r, in order for the web server to read them.
  • Directory listings are on by default. If you'd like the web server to generate directory listings, you need to make sure the desired directory is readable and searchable by all, orchmod o+rx.

If you're not doing one of the above things, you'll get a nasty forbidden message when you try to access a problematic file in your browser.

If you require personal web space attached to your user School of Computing user account, please submit a request to ithelp@clemson.edu with a reference to the School of Computing in the subject line.