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===== SoCS SSH Access =====

==== The Basics ====

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.

==== Accessing your SSH Client ====

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

=== Windows ===

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:

{{:techsupport:guides:ssh_windows_client.png?400|SSH Command Output}}

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

=== Mac OS ===

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

=== Linux ===

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 from Off-Campus ====
As of October 2022, new restrictions are in place when connecting from off campus.

- All ssh connections from off campus must first be to portkey.socs.uoguelph.ca. Once connected to portkey you can then ssh to the SoCS server you are trying to reach (likely linux.socs.uoguelph.ca)
  - An SSH Key is required to access Portkey from off campus. See the section below for details on setting one up.

==== 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_rsa.pub"  without the quotes
  - Copy the long string of text that begins with ssh-rsa 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) ===

- 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)
  - 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.
  - 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
  - Paste in the long string of text that you copied to your clipboard in step A
  - Save the file.
  - Log out of the server.

=== Part B For all platforms (OFF CAMPUS ONLY) ===
  - 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.
  - 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.
  - Once the key has been added to the server, attempt to ssh from off campus using //ssh central-ID@portkey.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_rsa//)
    * **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).
  - After connecting to portkey, ssh again into central-ID@linux.socs.uoguelph.ca to ensure that your connection is successful.

=== Part C For all platforms ===
  - Open terminal window, or Powershell (Windows only)
  - ssh to portkey.socs.uoguelph.ca
  - 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//).
  - This login method works for secure FTP programs too, such as filezilla, which will allow you to ftp files directly to your linux account.

Once you have your ssh keys set up you will be able to use them to log in to any SoCS Linux server.

== Advanced User Guide ==

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

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