Linux Networking that you need to know (Episode 3)

Introduction

This tutorial covers essential Linux networking concepts as presented in Episode 3 of David Bombal's series. It is designed for beginners who want to enhance their skills in Linux, particularly in networking. Mastering these concepts is crucial for anyone interested in hacking or cybersecurity.

Step 1: Understanding Basic IP Addressing

• Learn about IPv4 addressing:
  • IPv4 addresses consist of four octets (e.g., 192.168.1.1).
  • Each octet can range from 0 to 255.
• Familiarize yourself with the concept of subnetting:
  • Subnet masks (e.g., 255.255.255.0) determine the network and host portions of an IP address.

Step 2: Exploring Fundamental Linux Commands

• Get comfortable with basic commands:
  • ifconfig: Displays network interface configurations.
  • iwconfig: Shows wireless network interface configurations.
  • ip address: A newer command that combines ifconfig and route.
• Practice using these commands in the terminal to gather information about your network interfaces.

Step 3: Setting Up a Wireless Interface for a Virtual Machine

• Ensure your virtual machine settings allow for wireless connectivity:
  • Check your VM software (e.g., VirtualBox, VMware) for network configuration options.
  • Set the network adapter to "Bridged Adapter" to connect directly to your network.
• Use iwconfig to verify that your wireless interface is recognized by the system.

Step 4: Discovering Wireless Devices

• Utilize tools to scan for nearby wireless devices:
  • Use iwlist command:

    sudo iwlist wlan0 scan
    

• This command will provide a list of available networks and their details, such as SSID and signal strength.

Step 5: Pinging Targets

• Test connectivity to devices on your network:
  • Use the ping command:

    ping 192.168.1.1
    

• Interpret the results to determine if a device is reachable.

Step 6: Understanding DNS

• Learn about the Domain Name System:
  • DNS translates human-friendly domain names to IP addresses.
• Practice using the nslookup or dig command to query DNS records:

  nslookup example.com
  

Step 7: NMap Basics

• Install NMap, a powerful network scanning tool:

  sudo apt-get install nmap
  

• Use NMap to scan your local network:

  nmap -sP 192.168.1.0/24
  

• Understand the output, which lists live hosts and their IP addresses.

Step 8: Analyzing TCP/IP Headers

• Familiarize yourself with the structure of TCP/IP headers:
  • Understand fields such as source and destination ports, sequence numbers, and checksums.
• This knowledge is vital for network analysis and troubleshooting.

Step 9: Using Wireshark

• Install Wireshark for packet analysis:

  sudo apt-get install wireshark
  

• Capture packets on your network interface and analyze the traffic:
  • Look for patterns, protocols, and potential security issues.

Step 10: Changing MAC Address

• Learn how to change your MAC address for privacy or testing:

  sudo ifconfig wlan0 down
  sudo ifconfig wlan0 hw ether 00:11:22:33:44:55
  sudo ifconfig wlan0 up
  

• Verify the change using ifconfig.

Conclusion

In this tutorial, you have learned essential Linux networking concepts, from basic IP addressing to using advanced tools like NMap and Wireshark. These skills are fundamental for anyone looking to advance in hacking or cybersecurity. Continue practicing these commands and tools to strengthen your understanding and proficiency in Linux networking.