SSH

Here's a step-by-step guide to setting up SSH on your Ubuntu desktop:

First, check if SSH is installed by running:

ssh -V

If it's not installed, install it using:

sudo apt update && sudo apt install -y openssh-server

After installation, verify that SSH is running:

sudo systemctl status ssh

If it's not active, start it:

sudo systemctl start ssh

To enable SSH on startup:

sudo systemctl enable ssh

Edit the SSH configuration file:

sudo nano /etc/ssh/sshd_config

Some recommended changes:

Change the default port (optional for security):
```
Port 2222
```
Disable root login:
```
PermitRootLogin no
```
Allow only specific users (replace your_username with your actual username):
```
AllowUsers your_username
```
Disable password authentication if you plan to use SSH keys:
```
PasswordAuthentication no
```

After making changes, save and restart SSH:

sudo systemctl restart ssh

If UFW is enabled, allow SSH:

sudo ufw allow OpenSSH

Or, if you changed the port:

sudo ufw allow 2222/tcp

Check the firewall status:

sudo ufw status

Enable UFW if it's not active:

sudo ufw enable

On your local machine (the one you’ll use to connect):

ssh-keygen -t rsa -b 4096

Press Enter to save the key in the default location (~/.ssh/id_rsa).

Now, copy the public key to your Ubuntu desktop:

ssh-copy-id your_username@your_server_ip

Alternatively, manually copy the key:

cat ~/.ssh/id_rsa.pub | ssh your_username@your_server_ip "mkdir -p ~/.ssh && cat >> ~/.ssh/authorized_keys"

Set correct permissions:

ssh your_username@your_server_ip
chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keys

From your local machine:

ssh your_username@your_server_ip

If you changed the port:

ssh -p 2222 your_username@your_server_ip

Check logs for issues:

sudo journalctl -u ssh --no-pager | tail -20