Tux Toolkit

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Mastering Your SSH Config

Wait... SSH has a config?

Yep, it sure does!

Ok you might have already known that, maybe that's why you're here, but it took me a while to realise I could customise my SSH experience. And it turns out to be ridiculously easy!

So why Bother?

Using SSH is easy, right? Just type:

ssh user@ip

…and you're in. Done.

But who can remember all those IP addresses? We have phone books for phone numbers, why not IP books?

You could absolutely use shell aliases to remember all the IP addresses you need to connect to, but I want to show you why using the SSH config can give you so much more control!

Aliases: A Better Alternative

Let's start simple: replacing those clunky aliases with something cleaner.

If you're anything like I was, you probably have a bunch of SSH aliases like this:

alias ssh-ent=ssh [email protected]

Instead, you can add this to your SSH config file (~/.ssh/config):

Host ent
    Hostname enterprise.uss
    User spock

Now, connecting is as simple as:

ssh ent

Same convenience, less clutter. And it gets better.

Shared Configuration

One of the biggest perks of SSH config is reusable settings.

For example, if you use the same username across multiple servers, you don't have to repeat yourself:

Host ent voy ds9
    User spock

Now, ssh ent, ssh voy, and ssh ds9 all default to the same username.

Less typing, more efficiency.

Ever connect to a server only to immediately cd somewhere else? Maybe to your project's root folder or a logs directory?

You can automate that with the RemoteCommand option:

Host ent
    Hostname enterprise.uss
    User spock
    RequestTTY yes
    RemoteCommand cd /home/spock/bridge && /bin/bash --login

Now, every time you ssh ent, you'll land exactly where you need to be.

⚠ Important: You must include RequestTTY yes, or SSH will close immediately after running the command.

Running Commands on a Remote Server

Sometimes, you just need to run a quick command without opening a full session.

Instead of typing this every time:

ssh [email protected] /usr/bin/engage

You can define it in your SSH config:

Host engage
    Hostname enterprise.uss
    User picard
    RemoteCommand /usr/bin/engage

Now, running the command is as simple as:

ssh engage

Effortless.

Tips & Tricks

Obfuscating SSH Ports

By default, SSH runs on port 22, making it that port a common target for bots and brute-force attacks.

A simple way to make your server less visible (but not necessarily more secure) is to change the SSH port:

Host ent
    Hostname enterprise.uss
    User spock
    Port 493

Now, you don't have to remember the port when connecting—SSH does it for you.

🔒 Note: Changing the port is just obfuscation, not security. Always use firewalls, fail2ban, and proper SSH keys for real protection.

Managing Different Security Levels

Not all SSH keys are created equal.

For example:

  • Your GitHub key might be passwordless for convenience.
  • Your production server key might be password-protected for extra security.

Instead of manually specifying keys each time, let SSH config handle it:

Host ent
    Hostname enterprise.uss
    User spock
    IdentityFile ~/.ssh/secure_ed25519

Now, ssh ent will automatically use the correct key.

Simplifying GitHub Cloning

SSH config isn't just for logging into servers—it can also make Git operations smoother.

Instead of typing:

git clone [email protected]:username/repo

You can define a GitHub shortcut:

Host github.com
    IdentityFile ~/.ssh/git_ed25519  # If you use a specific SSH key for GitHub

Host gh
    Hostname github.com
    User git

Now cloning is as easy as:

git clone gh:username/repo

Shorter, cleaner, faster.

Boosting Performance with Compression

If you're on a slow connection, enabling SSH compression can speed things up:

Host *
    Compression yes

This is especially useful for low-bandwidth networks (e.g., mobile data, satellite internet).

⚠ However: Avoid using compression when transferring large compressed files (like .zip or .tar.gz), as it won't help and may even slow things down.

Advanced Tips

Now that we've covered the basics let's take a look at a few useful settings that you might not have known SSH could do.

Keeping the Connection Alive

Some firewalls kick connections that have been idle for a period of time. If you find you've been kicked out of a server after just a few minutes then this setting is for you.

Host *
    ServerAliveInterval 60

This option will tell SSH to ping the server every 60 seconds just to let it know you're still active.

Forwarding Identity Keys

If you ever find yourself needing to SSH into multiple servers one after the other, it can be frustrating to have to exit out just to SSH somewhere else. However there is a setting that allows you to tell SSH to keep using your SSH key even within an SSH session.

Host *
    ForwardAgent yes

Sadly this does not also forward your new awesome config, so you may want to exit out anyway so you can use your shortcuts.

Example Config

Let's put it all together and see what a wicked SSH config might look like.

# ==============================
# Spock's Starfleet SSH Config
# ==============================

# General settings for all hosts
Host *
    User spock              # Most servers use this name, and it can be overridden if needed
    Compression yes         # Enable compression for text-heavy SSH sessions
    ServerAliveInterval 60  # Keep connections alive
    ForwardAgent yes        # Enable SSH agent forwarding

# -----------------------------------
# USS Enterprise - Science Operations
# -----------------------------------
Host ent
    Hostname enterprise.uss
    Port 1701              # Custom port for security through obscurity
    IdentityFile ~/.ssh/starfleet_ed25519
    RequestTTY yes
    RemoteCommand cd /home/spock/science_lab && /bin/bash --login

# -----------------------------------
# Deep Space Nine - Science Division
# -----------------------------------
Host ds9
    Hostname deepspace9.uss
    Port 499
    IdentityFile ~/.ssh/starfleet_ed25519
    RemoteCommand cd /home/spock/ds9_science && /bin/bash --login

# -----------------------------------
# Vulcan Science Academy - Remote Access
# -----------------------------------
Host vulcan
    Hostname science.vulcan
    Port 2001
    IdentityFile ~/.ssh/vulcan_ed25519
    RemoteCommand cd /home/spock/logic_laboratory && /bin/bash --login

# -----------------------------------
# GitHub (Starfleet Open Source Contributions)
# -----------------------------------
Host github.com
    IdentityFile ~/.ssh/starfleet_git_key

Host gh
    Hostname github.com
    User git

Final Thoughts

SSH config is one of the most underrated productivity boosts for developers and sysadmins.

With just a little tweaking, you can:

  • Simplify server access (no more IP addresses!)
  • Automate repetitive tasks (like cd after login)
  • Enhance security & performance

So, what's stopping you? Open up ~/.ssh/config and start making SSH work for you.