Skip to content

CS Linux Cluster (linux.cs.odu.edu)

The CS Systems Group operates 4 multiuser linux servers running Ubuntu 22.04 Server. These servers are available to all students and faculty, and have all dependancies required to complete coursework for undergraduate CS classes.

The Linux cluster is only reachable when connected to the CS VPN.

To connect to the linux cluster, you must use SSH (Secure Shell) An example SSH command to connect to the cluster:

ssh cs_jdoe001@linux.cs.odu.edu

You can also use other SSH Clients such as PuTTY or MobaXterm, as well as X2Go clients.

Connecting to linux.cs.odu.edu will automatically connect to one of the servers shown in the table below, but if you wish to connect to a specific server you can also choose one of the following instead of linux.cs.odu.edu:

  • callisto.cs.odu.edu
  • europa.cs.odu.edu
  • ganymede.cs.odu.edu
  • io.cs.odu.edu

For more details about SSH and how to set up an SSH client if you don't have one, visit our SSH Documentation

Home Directory

When you connect to a CS Linux Server, your working directory will be your Home Directory. Your Home Directory is shared between all CS Linux Servers, and is also available on CS Desktops as the Z: Drive.

By default, undergraduate home directories are 15G and graduate home directories are 30G.

For troubleshooting and more information about Home Directories, visit the Home Directories page.

Unix Permissions

Security of your files is important and needs to be considered when working on the servers, since they are available to all CS students and faculty. To further understand how file permissions work in linux, you can read visit our Unix Permissions page.

Submitting cron jobs to the public Linux Cluster

When you add a cron job to your crontab on one of the hosts in the cluster, by default that job will run on every host in the cluster.

If you want a job to only run on one host you can prefix your job with /usr/bin/rcron. This system has failover so if multiple hosts in the cluster go down as long as there is one host up your job will continue to run.

A job using rcron looks like this:

12 11 * * * /usr/bin/rcron myjob

If you want to run a job on a specific host, you can include a hostname check so that it will only run on the specific host that you want it to.

0 * * * * [ "$(hostname)" != "io" ] || /usr/games/fortune

Common Questions or Issues

While attempting to connect to the servers, you might run into some issues. Some are listed here but if you run into any more you can contact us at root@cs.odu.edu.

ssh: Could not resolve hostname linux.cs.odu.edu: Name or service not known error when logging in

This error occurs when you try to connect to the server from outside the CS network. Ensure that you are connected to the VPN and try again.

If you are connected to the VPN but still receive this error, your computer likely has the wrong DNS servers set or cannot reach the CS DNS servers.

You can try the command ping 172.18.8.18 to ensure you can reach our DNS server

ssh: connect to host linux.cs.odu.edu port 22: Connection timed out error when logging in

This error occurs when your computer is not able to reach the server. This can occurr when connecting from an ODU computer that is not on the CS network, or when connecting from a personal device on ODU's WiFi without first connecting to the VPN.

This error can also occur if the server you are trying to connect to is offline. You can check the status of CS Services and Servers on the CS Status page.

Permission denied (publickey,password) error when logging in

This error occurs when you provide an incorrect username or password when logging in. The most common cause is not including cs_ in your username. Other common causes are an expired password, not having a CS Account, or your account being archived or disabled. If you are able to log into the VPN and Accounts Management with your CS credentials, but still receive this error when logging into the linux cluster, contact us at root@cs.odu.edu

Could not chdir to home directory /home/<username>: No such file or directory error after logging in

This error occurs when the server is not able to connect to your home directory. This issue often requires assistance from root@cs.odu.edu to resolve, but some basic troubleshooting steps may help find the problem

  • check that the username you logged in with matches the username in the error. If it does not, contact root and include that information.
  • run the command ls -ld /home/<username> with your CS username. If you receive the error No such file or directory, contact root. If you do not receive that error, try manually changing to your home directory cd /home/<username>. If the issue recurs on every login, contact root.