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How To: SSH

We connect to our servers for many reasons:

  • Updating the server or services
  • Starting new services
  • Other maintenance
  • Investigations
  • etc.

To do this, we use a piece of software called Secure Shell (SSH) ⧉.

The way SSH works is by essentially creating a terminal (Think Command Prompt) on the server that a terminal on your computer connects to. Cool, huh?

Before we continue, please make sure you have followed the Setting up Technically Guide.

Your First Connection

With your generated SSH key (For this doc, let's say my SSH Private Key is /home/bitflip/.ssh/cspp), open a terminal, like Terminal for MacOS or PowerShell for Windows.

We're going to connect to our cloud server, Huey Dewey Louie!

Then type the following command:

Bash
ssh [email protected] -i /home/bitflip/.ssh/cspp

# Don't forget to change the path of the key with your path!

You'll see this big scary message that reads something like this:

Text Only
The authenticity of host 'hdl.cspp.ie (158.220.114.253)' can't be established.
ED25519 key fingerprint is SHA256:AMbW9QGVEgxijwaoAgZijtzkS4RiHUpL80XVpluZCR0.
Are you sure you want to continue connecting (yes/no/[fingerprint])?

Type the word yes and press ENTER to continue! This is you just confirming that you trust the server.

Assuming your key was configured correctly, you'll see something like this:

Bash
Welcome to Ubuntu 22.04.4 LTS (GNU/Linux 5.15.0-25-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/pro

     _/_/_/    _/_/_/      _/          _/
  _/        _/            _/          _/
 _/          _/_/    _/_/_/_/_/  _/_/_/_/_/
_/              _/      _/          _/
 _/_/_/  _/_/_/        _/          _/

Welcome CS++ Administrator!

Last login: Fri Jul 5 17:19:39 2024 from ███.███.███.███
bitflip@huey-dewey-louie:~$

Updating Your Password

Since your account was just created, the Sysadmin should have given you a TEMPORARY PASSWORD. This password will require you to change it on first log in.

It'll look like this:

Bash
You are required to change your password immediately (administrator enforced).
Changing password for USERNAME.
Current password:

Enter your temporary password in Current password:

Then enter a new password for your user.

The password section will remain blank as you type!

You just made your first SSH connection to CS++ infrastructure, congrats!

But How Do I Get Out?

To disconnect, you can type the following:

Bash
bitflip@huey-dewey-louie:~$ exit

You'll then see this in your terminal:

Bash
logout
Connection to hdl.cspp.ie closed.

You have now logged out!

Connecting Made Simple

If you're going to SSH regularly, then you can create a config file for SSH.

Go to where your .ssh folder is. On MacOS / Linux, it is normally /home/[USERNAME]/.ssh, for Windows, you'll find it in /c/Users/[USERNAME]/.ssh

Create a file called config, and open it in a text editor.

If you want to connect to Huey Dewey Louie regularly, add the following:

Bash
Host huey
        Hostname hdl.cspp.ie
        User [USERNAME]
        IdentityFile [path/to/key]

Fill in the placeholders with your username on the server, and the path to your key, then save and close the file.

Now open a terminal again and type:

Bash
ssh huey

You'll be prompted to trust the server again, just type yes again, and you'll be greeted with the same CS++ Logo!

It's so much easier to type than having to enter your username, domain of the server, and where your key is stored.

Connecting to Other Servers

Head on over to the hardware section of these docs to get the domain / IP of the server you wish to connect to!

Happy SSHing!