Remote Access Setup for Debian-based Linux (SSH + VNC)

SSH Keys Setup

SSH keys provide a secure way of logging into your server and are recommended for all users. The steps for setting up SSH keys on Linux are as follows:

Open Terminal.
In the Terminal window, enter the following command to generate a new SSH key. Replace “your_email@example.com” with your actual email address.
```
 ssh-keygen -t rsa -b 4096 -C "your_email@example.com"
```
Press Enter to accept the default location for your SSH key files. You’ll be asked to enter a passphrase. This is optional but recommended for additional security.
Once the keys are generated, you can display the public key in Terminal with the following command:
```
 cat ~/.ssh/id_rsa.pub
```
Now you can copy the output and paste this key into the SSH Keys section of your server or service that requires SSH authentication.

SSH Port Forwarding

SSH port forwarding, also known as SSH tunneling, is a method of transporting arbitrary networking data over an encrypted SSH connection. Here’s how to set it up:

Open Terminal.
Use the following command to start an SSH tunnel. Replace the placeholders as follows:
- <local-port>: The local port on your machine.
- <remote-host>: The remote host you’re connecting to.
- <remote-port>: The remote port on the remote host.
```
 ssh -L <local-port>:localhost:<remote-port> <remote-host>
```
If the command is successful, your SSH tunnel is set up and ready to use!

VNC Viewer Setup

For Linux, we’ll use TigerVNC Viewer as an example. Here’s how to install and use it:

Open Terminal.
Use the following command to install TigerVNC Viewer:
```
 sudo apt install tigervnc-viewer
```
To open VNC Viewer, enter the following command:
```
 vncviewer
```
In the “VNC server” field, enter the IP address of the machine you wish to connect to.
Click “Connect.”

Connecting to VNC through SSH Port Forward

To securely connect to a VNC server, you can tunnel your VNC traffic through the SSH connection that you’ve set up:

First, set up the SSH tunnel with the following command. Replace the placeholders as before, and use 5900 as the <remote-port>, as this is the default port that VNC servers listen on.
```
 ssh -L <local-port>:localhost:5900 <remote-host>
```
Then, in VNC Viewer, in the “VNC Server” field, instead of entering the remote host’s IP address, enter localhost:<local-port>, where <local-port> is the local port you used in the SSH command.
Click “Connect.”

Congratulations, you’re now connected to your remote host via VNC over a secure SSH tunnel!

Starting a VNC Server on the Remote Machine

If a VNC server is not started on the remote machine, you will need to do so yourself. To start a VNC server on the remote machine, you’ll need to SSH into it and run the vncserver command. Here’s how:

Open Terminal.
Use the ssh command to connect to your remote machine. Replace <remote-host> with the hostname or IP address of your remote machine.
```
 ssh <remote-host>
```
Once you’re logged into your remote machine, you can start the VNC server by running the vncserver command. If you want to specify a port, you can do so by adding :<display-number> to the command. The actual port number will be 5900 plus the <display-number>. For example, if you choose 1 as your display number, the port number will be 5901.
```
 vncserver :<display-number>
```
You’ll be prompted to enter and confirm a password. This is the password you’ll use to connect to the VNC server from your VNC Viewer.

Note: This section assumes that the remote server runs linux. If you are not sure which port to use, start with 1 (:1). If that port is in use, the system will tell you, and you can try higher numbers. You should avoid using display numbers below 1 as they may be used by system services. You should also avoid using display numbers above 99 to avoid port conflicts.