Install and Configure SSH Services - CSU360

Practical 8: Perform an operation of operating system to install and configure: A. SSH service, and B. HTTP Service

8.A. Introduction to SSH Services

Secure Shell (SSH) is a cryptographic network protocol essential for secure communications over insecure networks like the internet. It facilitates secure system administration and file transfers, leveraging a client-server model where both SSH client and server applications are utilized.

8.A.1. The SSH Protocol

SSH supports logging into remote machines, executing commands, tunneling, forwarding TCP ports, and X11 connections. It employs public-key cryptography to authenticate the remote computer and allow user authentication.

8.A.2. Installing and Configuring SSH on Kali Linux

SSH services on Kali Linux are managed via the OpenSSH package. The installation involves updating package lists and installing OpenSSH:

sudo apt update
sudo apt install openssh-server

Figure 8.A.2.1: Installing SSH

Configuration adjustments are made in the SSH daemon configuration file (/etc/ssh/sshd_config), such as changing the default port, disabling root login, and enforcing public key authentication over passwords.

sudo nano /etc/ssh/sshd_config
# Make changes: Port 2222, PermitRootLogin no, PasswordAuthentication no
sudo systemctl restart ssh

Figure 8.A.2.2: Configuring SSH

8.A.3. Managing SSH Service

Ensure the SSH service starts automatically at boot and verify it's running correctly:

sudo systemctl start ssh
sudo systemctl enable ssh
sudo systemctl status ssh
systemctl is-enabled ssh

Figure 8.A.3.1: Managing SSH Service

8.A.4. Setting Up SSH Key Pair and Connection

Generate an SSH key pair on the client machine for secure authentication and copy the public key to the Kali SSH server:

ssh-keygen -t rsa -b 4096

Figure 8.A.4.1: SSH Key-Pair Generation

ssh-copy-id -i ~/.ssh/id_rsa.pub -p 2222 username@your-kali-ip-address

Figure 8.A.4.2: SSH Key-Pair based connection

Test the SSH connection using the configured settings:

ssh -p 2222 username@your_kali_ip_address

Figure 8.A.4.3: SSH Connection using the previous connection

8.A.5. Advanced SSH Configuration

Further enhance security by configuring additional parameters in the SSH configuration file:

sudo nano /etc/ssh/sshd_config
# Adjust settings: X11Forwarding no, UseDNS no, AllowUsers username
sudo systemctl restart ssh

Figure 8.A.5.1: Advanced SSH Configuration.

8.B.1. Introduction to HTTPD Services

The Apache HTTP Server, commonly known as HTTPD, is an open-source web server software developed by the Apache Software Foundation. HTTPD stands for HTTP Daemon and is a crucial component for web server deployment. It is designed to create and host web pages, handling requests and responses across the internet.

8.B.2. The HTTPD Architecture

HTTPD uses a modular architecture that allows for a high degree of customization and configuration. It supports a variety of features including SSL/TLS for secure communication, URL rewriting, and load balancing. The server processes requests using a multi-processing module which can be configured to suit the performance needs of different environments.

8.B.3. Installing HTTPD on Kali Linux

To install HTTPD on Kali Linux, you can use the apt package manager:

sudo apt update
sudo apt install apache2

This installs the Apache2 package, setting up HTTPD on your Kali machine.

Figure 8.B.3.1: Installing HTTPD on Kali Linux

8.B.4. Configuring HTTPD

After installation, configuration of HTTPD is important for security and performance optimization. Common configurations involve:

sudo nano /etc/apache2/apache2.conf

Figure 8.B.4.1: Configuring HTTPD.

This command opens the main configuration file where you can adjust settings for directory access, performance tweaks, and more. Typical changes include:

ServerTokens: Set to 'Prod' to minimize information leakage about the server version.
ServerSignature: Turn off to disable server signature on error pages and server-generated documents.
KeepAlive: Adjust according to traffic patterns to optimize performance.

Save the configuration changes and restart the HTTPD service to apply them:

sudo systemctl restart apache2

Figure 8.B.4.1: Restarting HTTPD.

8.B.5. Enabling and Starting HTTPD Service

Ensure HTTPD starts at boot and is running:

sudo systemctl start apache2
sudo systemctl enable apache2

Figure 8.B.6.1: Enabling and Starting HTTPD Service.

8.B.6. Checking HTTPD Service Status

Verify that the HTTPD service is active and running:

sudo systemctl status apache2

Look for 'active (running)' in the output to confirm that the server is operational.

Figure 8.B.6.1: Checking status of HTTPD Service.

8.B.7. Accessing the HTTPD Web Server

Test your HTTPD setup by accessing the default Apache welcome page through your web browser:

firefox http://localhost

This should display the Apache2 Ubuntu default page, indicating the web server is correctly installed and running.

Figure 8.B.7.1: Launch localhost.

Figure 8.B.7.2: localhost hosted page.

8.B.8. Modifying the Content of the Default Index.html File in HTTPD (optional)

The default 'index.html' file is typically located in the 'html' directory of Apache's document root. To modify the content of this file, you need to locate it and then use a text editor to make changes.

cd /var/www/html
sudo nano index.html

In the nano editor, you can modify the HTML content as needed. For example, to change the welcome message, you might edit the body of the HTML to include your new content:

<html>
<head>
    <title>Welcome to My Website</title>
</head>
<body>
    <h1>Hello, welcome to my new Apache server!</h1>
    <p>This is the new content of the default index page.</p>
</body>
</html>

After making your changes, save the file and exit the editor. The changes will be visible immediately when you access your server's IP address or domain in a web browser.

8.B.9. Changing the Default Index Page in HTTPD (optional)

To change the default index page used by HTTPD, you'll need to modify the 'DirectoryIndex' directive in the configuration file. This defines which files should be served as the index page when a directory is accessed without a specific file name being requested.

sudo nano /etc/apache2/mods-enabled/dir.conf

In the 'dir.conf' file, find the 'DirectoryIndex' directive and adjust it to your new default index file:

DirectoryIndex newindex.html

Replace 'newindex.html' with the name of your new default index file. After saving the changes, restart the HTTPD service to apply them:

sudo systemctl restart apache2

This change will direct HTTPD to use 'newindex.html' as the default page for directories where no specific file is requested.