Setting Up SSH Server Between PC and Server

This guide explains how to set up and configure an SSH server to enable secure communication between a client PC and a server.

Prerequisites

1. A Linux-based PC (client) and server.
2. SSH package installed on both machines.
3. Network connectivity between the PC and the server.

Step-by-Step Instructions

Step 1: Install OpenSSH

On both the client and server, install the OpenSSH package:

On the Server:

sudo apt update
sudo apt install openssh-server

On the Client:

sudo apt update
sudo apt install openssh-client

Step 2: Start and Enable SSH Service

Ensure the SSH service is running on the server:

sudo systemctl start ssh
sudo systemctl enable ssh

Check the service status:

sudo systemctl status ssh

Step 3: Configure SSH on the Server

1. Open the SSH configuration file:

   sudo nano /etc/ssh/sshd_config
   

2. Modify or verify the following settings:

   • PermitRootLogin: Set to no for security.
   • PasswordAuthentication: Set to yes to allow password-based logins initially (you can disable it after setting up key-based authentication).

3. Save changes and restart the SSH service:

   sudo systemctl restart ssh
   

Step 4: Determine the Server’s IP Address

Find the server’s IP address to connect from the client:

ip a

Look for the IP address under the active network interface (e.g., 192.168.x.x).

Step 5: Test SSH Connection from the Client

On the client, open a terminal and connect to the server using:

ssh username@server_ip

Replace username with the server’s username and server_ip with the actual IP address.

Example:

ssh user@192.168.1.10

**Step 6: Set Up Key-Based Authentication

1. On the client, generate an SSH key pair:

   ssh-keygen -t rsa -b 4096
   

2. Copy the public key to the server: on Linux

   ssh-copy-id username@server_ip
   

   on Windows go to the .ssh folder

scp $env:USERPROFILE/.ssh/id_rsa.pub username@ip:~/.ssh/authorized_keys

1. Verify key-based login:

   ssh username@server_ip
   

2. Disable password-based logins for added security:

   • Edit the server’s SSH configuration file:

     sudo nano /etc/ssh/sshd_config
     

   • Set PasswordAuthentication to no.

   • Restart the SSH service:

     sudo systemctl restart ssh
     

Step 7: Troubleshooting Common Issues

• Firewall: Ensure SSH traffic is allowed through the firewall on the server:

  sudo ufw allow ssh
  sudo ufw enable
  

• Connection Refused: Check if the SSH service is running and the correct IP address is used.