SSH

SSH stands for Secure Shell. It is a commonly used protocol that allows you to connect to a remote machine and execute commands on it. Learn more about SSH here (opens in a new tab).

Quick Start

Here's a tool to help you generate a personalized SSH command. This tool will generate a command that you can copy and paste into your terminal. Note that the commands generated by this tool are only tested on Linux and macOS.

Command Generator

Choose your preferred machine and fill in the fields below to obtain personalized SSH commands.

The generated commands do not require setting up ssh agent¹ or ssh config². However, you may soon find that setting them up will make your life easier. If you are interested in learning more about these tools, please check out Tips and Tricks and the official documentation linked in the footnotes.

Syntax

The general syntax for connecting to the cluster is:

SSH_KEY_PATH="<path_to_ssh_key>"
SSH_USERNAME="<username>"
SSH_HOST="<hostname>"
ssh -v -i "$SSH_KEY_PATH" "$SSH_USERNAME@$SSH_HOST"

or if you are using a jump host:

SSH_KEY_PATH="<path_to_ssh_key>"
SSH_USERNAME="<username>"
SSH_HOST="<hostname>"
SSH_JUMP_HOST="<jump_host>"
ssh -v -o ProxyCommand="ssh -W %h:%p -i \"$SSH_KEY_PATH\" \"$SSH_USERNAME@$SSH_JUMP_HOST\"" -i "$SSH_KEY_PATH" "$SSH_USERNAME@$SSH_HOST"

Tips and Tricks

Additional SSH Keys

To use additional SSH keys, you have the following options:

1. Update your profile to add additional SSH keys.
2. Manually create ~/.ssh/authorized_keys and place your SSH keys in there.You'll need to make sure that this file is present in all machines that you want to connect to³.

SSH Agent

SSH agent is useful for many reasons, for example:

1. It removes the need to use the -i flag to specify the path to your SSH key.
2. It allows you to use SSH agent forwarding (opens in a new tab).

You can use SSH agent as follows:

# Start an SSH agent if it's not already running
[[ -z "$SSH_AUTH_SOCK" ]] && eval "$(ssh-agent -s)"
# Add your SSH key to the agent. Replace ~/.ssh/id_rsa with the path to your SSH key.
ssh-add ~/.ssh/id_rsa
# Connect to the cluster
ssh -v "<ssh_username>@<ssh_host>" # This is the same as ssh -v -i ~/.ssh/id_rsa "<ssh_username>@<ssh_host>" without SSH agent
# or if you are using a jump host
ssh -v -o ProxyCommand="ssh -W %h:%p \"<ssh_username>@<ssh_jump_host>\"" "<ssh_username>@<ssh_host>"

~/.ssh/config

If you find yourself using the same SSH command over and over again, you can use ~/.ssh/config to simplify your life.

For example, if you find yourself using the following command often:

ssh -v -o ProxyCommand="ssh -W %h:%p -i \"<ssh_key_path>\" \"<ssh_username>@<ssh_jump_host>\"" -i "<ssh_key_path>" "<ssh_username>@<ssh_host>"

you can add the following to your ~/.ssh/config:

Host <ssh_jump_host>
    HostName <ssh_jump_host>
    User <ssh_username>
    IdentityFile <ssh_key_path>
 
Host <ssh_host>
    HostName <ssh_host>
    User <ssh_username>
    IdentityFile <ssh_key_path>
    ProxyJump <ssh_jump_host>

and then simply run:

ssh -v <ssh_host>

A real-world example of this is:

Host bastion
    HostName bastion.watonomous.ca
    User alex
    IdentityFile ~/.ssh/id_rsa
 
Host derek3-ubuntu2
    HostName derek3-ubuntu2.cluster.watonomous.ca
    User alex
    IdentityFile ~/.ssh/id_rsa
    ProxyJump bastion

ssh -v derek3-ubuntu2