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SSH

## Install SSH

#!/bin/bash

ssh -V

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

# verify its running
sudo systemctl status ssh

# start
sudo systemctl start ssh
# on boot
sudo systemctl enable ssh

Edit the SSH configuration file:

#!bin/bash

```bash
sudo nano /etc/ssh/sshd_config

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

Step 3: Allow SSH Through Firewall

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

Step 5: Connect to Your Ubuntu Desktop via SSH

From your local machine:

ssh your_username@your_server_ip

If you changed the port:

ssh -p 2222 your_username@your_server_ip

Step 6: Troubleshooting

  • Check SSH service status:

    sudo systemctl status ssh

  • Restart SSH if needed:

    sudo systemctl restart ssh

  • Check firewall rules:

    sudo ufw status

  • Check logs for issues:

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