School of Computer Science Wiki

SSH is a program that allows you to log in to and run programs on a remote server. It is used in the School of Computer Science to allow access to our Linux Servers where you can edit, compile, and run code for your labs and assignments.

To use SSH to connect to SoCS Servers, you will first need an SSH client. SSH is available on all three main operating systems.

A built in client is now available on Windows. You can access it by opening Windows Powershell.

To check if ssh is installed, Open Windows Powershell, and type “ssh” followed by enter. You should see the following:

This client should be available by default, but if it is missing, follow the instructions in the Install SSH on Windows section below.

The SSH client comes automatically installed as part of Mac OS. To access the ssh client, open the Terminal application.

The OpenSSH Client is available through your Package Manager on all major Linux Distributions. To install the client on a Debian/Ubuntu based distribution using Apt, install the openssh-client package. To install on a RedHat based distribution using Yum, install the openssh-clients package. Once installed you can access ssh through your distribution's terminal application.

SSH connections from off campus are restricted by the campus firewall.

1. Preferred SSH Connections are enabled off-campus while running the Campus VPN. Follow the https://uoguelphca.sharepoint.com/sites/ccs/SitePages/anyconnect-vpn-user-guide.aspx] to install. Once the VPN is running, ssh to the server as you would from on campus. - Use SSH key based authentication to connect to Portkey from off campus, and then connect to the desired server. This is recommended only if you are unable to use the Campus VPN. Instructions on SSH Key setup are provided below. ==== Connecting to a Server ==== The commands to use SSH are the same from all operating systems. In general, the ssh command is ''ssh <username>@<hostname>.socs.uoguelph.ca'', where <username> is your Central Login ID and <hostname> is the name of the server you wish to connect to (i.e. linux, portkey). The following are examples of commands to connect to the Schools "linux.socs" servers. While the prompts look slightly different, the behaviour is identical. From Windows:\\ {{:techsupport:guides:ssh_command_windows.png?400|}}\\ From Mac OS or Linux:\\ {{:techsupport:guides:ssh_user_linuxmac.png?400|}} ==== Common Problems and Errors==== === Time Out === == Problem == After entering the ssh command there is a blinking cursor with no response, or the following error <code>ssh: connect to host linux.socs.uoguelph.ca port 22: Operation timed out</code> == Solution == If you are connecting from off campus, the most likely issue is that you are trying to connect directly to linux.socs.uoguelph.ca. You must first set up SSH keys (see the section below), and then from off campus you should first ssh to portkey.socs.uoguelph.ca, and from there to linux.socs.uoguelph.ca. === Permission Denied === == Problem == Every time you enter your password, you receive the following error: <code>Permission denied, please try again.</code> == Solution == The most likely cause is that you are not specifying your username when trying to connect. If you type ''ssh linux.socs.uoguelph.ca'' as your command, it will automatically use your computer's user account name as the username. Make sure you specify your username with ''ssh username@linux.socs.uoguelph.ca''. ==== Install SSH on Windows ==== * Open the Start Menu and click Settings\\ {{:techsupport:guides:start_settings.png?400|}} * Click on Apps\\ {{:techsupport:guides:settings_apps.png?400|}} * Click on Optional Features\\ {{:techsupport:guides:windows_apps_features.png?400|}} * Click on Add a Feature\\ {{:techsupport:guides:add_a_feature.png?400|}} * Lastly, click on OpenSSH Client, and then Install\\ {{:techsupport:guides:ssh_install.png?400|}} * You can now open Windows Powershell and use SSH ==== SSH Keys One Time Setup ==== SSH Keys are an advanced feature that allow you to use a key to connect instead of using your password. This has the benefit of being both more secure, and more convenient to use. As of October 2022, SSH keys are required to access the SoCS servers from Off Campus. Regular password based login is still allowed from on campus. Please note that SSH may not be enabled on your Windows machine by default. Follow the topic in this article on how to install SSH before continuing with this guide. To set up public key private key access to linux: === Part A For all platforms === - Have a passphrase (password) handy that you can remember. This should be different than your central login password. - Open a terminal window (or PowerShell for Windows) - Type ssh-keygen -t ed25519 -C central-ID@linux.socs.uoguelph.ca at the command prompt - Press return to accept the default file locations for storing keys - Enter your passphrase when prompted (make sure you can remember it) - Enter the SAME passphrase again - In the same terminal window, change to your .ssh directory. A foolproof way to do this is to first type cd followed by enter, then type cd .ssh - Type "more id_ed25519.pub" without the quotes - Copy the long string of text that begins with ssh-ed25519 and ends with yourusername@linux.socs.uoguelph.ca. It will wrap across several lines. - Keep that text in the clipboard for the next step and go to Part B (either for on campus or off campus, depending on your location). === Part B For all platforms === == On Campus Only == If you are working on campus, you can set can set up your keys using ssh. - ssh to linux.scos.uoguelph.ca using your Central Login ID and password (use PowerShell on windows if you don't have a different client. On OS/X and linux just use a terminal) == Off Campus Only == If you are working off campus you should use NoMachine to upload your ssh key. - Connect to NoMachine to facilitate the file transfer process. If you have not used NoMachine before, please reference our [[techsupport:guides:nomachine|guide to NoMachine here. NoMachine supports file transfer via scp and is our recommendation for off-campus students.
2. Once you have connected to NoMachine, open a terminal and follow the next steps.

1. Type “cd ~/.ssh” at the command prompt (without the quotes).
   • If you get an error “.ssh No such file or directory”, type “cd ~”, then “mkdir .ssh”, then type “cd .ssh”, otherwise ignore this step.
2. Use your favourite command line editor (vim, nano, emacs, etc.) to edit the authorized_keys file
   • i.e. type 'nano authorized_keys' at the command line
   • Unless you've done this step once already, you will be creating this file. it MUST be called authorized_keys
3. Paste in the long string of text that you copied to your clipboard in step A
4. Save the file.
5. Log out of the server.

1. Open terminal window, or Powershell (Windows only)
2. ssh to portkey.socs.uoguelph.ca
3. You SHOULD be prompted for the passphrase you used in Part A, and then you should connect to our linux servers (ssh central-ID@linux.socs.uoguelph.ca).
4. This login method works for secure FTP programs too, such as filezilla, which will allow you to ftp files directly to your linux account.

1. If you are unable to bring your private key to campus (via a laptop, removable storage device, etc.) and cannot transfer files via NoMachine, you must send your public key to help@socs.uoguelph.ca. Your public key will then be put into your home folder. This process may take up to a day to complete, so it is recommended to only use this option as a last resort.
2. Once the key has been added to the server, attempt to ssh from off campus using ssh central-ID@portkey.socs.uoguelph.ca, agreeing to any prompts that you receive while connecting. You will be prompted to input the password you saved during the keygen creation here.
   • If ssh is not able to find your private keys file, you can include the -i flag to specify the location of your keys (ex. ssh jdoe@uoguelph.ca -i ~/.ssh/id_ed25519)
   • NOTE: The portkey server is a jump server and has nothing installed. You will not be able to run/compile code on this server - its sole purpose is to connect you to the main server cluster (linux.socs.uoguelph.ca).
3. After connecting to portkey, ssh again into central-ID@linux.socs.uoguelph.ca to ensure that your connection is successful.

If you feel confident in your ability, below are the list of commands that you can execute to get your key onto the server while on campus. This guide is suited for students that can troubleshoot common Linux issues related to ssh and file movement. If you are not confident, follow Part A For all platforms above for a more in-depth guide.

Server-Side Setup

ssh central-ID@linux.socs.uoguelph.ca
cd ~
mkdir .ssh 
cd .ssh
ls
touch authorized_keys (if the file already exists, skip this step)

Local Machine

ssh-keygen -t ed25519 -C central-ID@linux.socs.uoguelph.ca 
scp ~/.ssh/id_ed25519.pub central-ID@linux.socs.uoguelph.ca:~/.ssh/ed25519.pub

On linux.socs.uoguelph.ca

cd ~/.ssh
cat ed25519.pub >> authorized_keys
exit

• Open up VSCode and click on the “Extensions” icon in the left sidebar. Search for “Remote - SSH” and install the extension.
• Once the extension is installed, click on the “Remote Explorer” icon in the left sidebar. Then, click on the “SSH Targets” dropdown and select “Add SSH Host”.
• In the “SSH Targets” dropdown, select “Configure SSH Hosts”. This will open up your SSH config file in VSCode
• In the SSH config file, add the following code

Host portkey
    Hostname portkey.socs.uoguelph.ca
    User your_username

  Host linux
    Hostname linux.socs.uoguelph.ca
    User your_username
    ProxyCommand ssh -q -W %h:%p portkey

• Replace your_username with your actual username for both the jump host and target box.
• Save the SSH config file and close it.
• In the “SSH Targets” dropdown, you should now see two new entries: “portkey” and “linux”. Click on “linux”.
• You'll be prompted to enter your password for the target box. Enter it and click “OK”.

VSCode will now open a new window with a terminal connected to the target box through the jump host. You can now work on files and run commands on the target box as if you were working on it directly.

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