CCST Networking Exam Preparation

This repository provides resources and examples for preparing for the CCST Networking exam. It includes study notes, practice questions, Packet Tracer files, and network performance testing examples using iperf3.

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1. Network Performance Testing with iperf3

   iperf3 is a tool for measuring network bandwidth. Below are some examples of how to use iperf3 for various network performance tests.

   Basic Bandwidth Test

   Situation: You want to measure the maximum bandwidth between a client and a server on a local network.

   On the server:

   iperf3 -s

   On the client:

   iperf3 -c <server_ip>

   Bandwidth Test with Custom Time Interval

   Situation: You need to measure bandwidth over a specific period.

   On the server:

   iperf3 -s

   On the client:

   iperf3 -c <server_ip> -t 60

   Test with Bandwidth Limiting

   Situation: You want to simulate network conditions by limiting bandwidth.

   On the server:

   iperf3 -s

   On the client:

   iperf3 -c <server_ip> -b 10M

   TCP Bandwidth Test with Custom Port

   Situation: You need to measure TCP bandwidth on a specific port.

   On the server:

   iperf3 -s

   On the client:

   iperf3 -c <server_ip> -p 5001

   UDP Bandwidth Test with Custom Port

   Situation: You need to measure UDP bandwidth and observe packet loss.

   On the server:

   iperf3 -s -u

   On the client:

   iperf3 -c <server_ip> -u  -p 5201

   SCTP Bandwidth Test with Custom Port

   On the server:

   iperf3 -s -p 5001 -t 30 -i 10 --sctp

   On the client:

   iperf3 -c <server_ip> -p 5001 -t 30 -i 10 --sctp

   Testing with Zero-Copy Mode

   Situation: You want to test performance using the zero-copy mode for potentially improved throughput.

   On the server:

   iperf3 -s -Z

   On the client:

   iperf3 -c <server_ip> -Z

   Test with Different Window Size

   Situation: You want to test how changing the TCP window size affects performance.

   On the server:

   iperf3 -s

   On the client:

   iperf3 -c <server_ip> -w 64K

   Multi-Client Testing

   Situation: You want to test bandwidth from multiple clients simultaneously to see how the server handles concurrent connections.

   On the server:

   iperf3 -s

   On the client:

   iperf3 -c <server_ip> -P 5

   Reverse Test Mode

   Situation: You want the server to act as the client and the client to act as the server, often used to test the reverse path bandwidth.

   On the server:

   iperf3 -s

   On the client:

   iperf3 -c <server_ip> -R

   UDP Test with Custom Packet Size

   Situation: You need to test how different packet sizes affect performance.

   On the server:

   iperf3 -s -u

   On the client:

   iperf3 -c <server_ip> -u -l 1024

   ---

2. Network Protocols: FTP, SFTP, TFTP, NTP and ICMP

   FTP (File Transfer Protocol)

   Overview: FTP is a standard network protocol used to transfer files between a client and a server over a network. It operates on TCP/IP and typically uses port 21 for control commands and port 20 for data transfer.

   Basic Commands and Examples:

   • Starting the FTP Server:

     • On Linux:

       sudo apt-get install vsftpd
       sudo systemctl start vsftpd

     • On Windows: Install and configure FileZilla Server.

   • Connecting to an FTP Server:

     • From a command-line client:

       ftp <server_ip>

       Enter username and password when prompted.

     • Using FileZilla Client:

       • Open FileZilla.
       • Enter the server IP, port 21, username, and password in the Quickconnect bar.

   • Common Commands:

     • List Files:

       ls

     • Upload File:

       put <local_file>

     • Download File:

       get <remote_file>

   Configuration Example: Ensure your server settings disallow anonymous logins and only allow authenticated users.

   ---

   SFTP (Secure File Transfer Protocol)

   Overview: SFTP is a secure protocol for transferring files over a network, using SSH (Secure Shell) to encrypt data and commands. It operates on port 22.

   Basic Commands and Examples:

   • Setting Up SFTP on Linux:

     • Install OpenSSH server:

       sudo apt-get install openssh-server

     • Start the SSH service:

       sudo systemctl start ssh

   • Connecting to an SFTP Server:

     • From a command-line client:

       sftp <username>@<server_ip>

       Enter the password when prompted.

     • Using WinSCP (Windows):

       • Open WinSCP.
       • Enter the server IP, port 22, username, and password.

   • Common Commands:

     • Upload File:

       put <local_file>

     • Download File:

       get <remote_file>

   Configuration Example: Ensure your sshd_config file allows SFTP and restricts users to their home directories for security.

   ---

   TFTP (Trivial File Transfer Protocol)

   Overview: TFTP is a simpler version of FTP used for transferring files with minimal overhead. It operates on UDP port 69 and is typically used for tasks like network booting.

   Basic Commands and Examples:

   • Installing and Starting TFTP Server on Linux:

     • Install tftpd-hpa:

       sudo apt-get install tftpd-hpa

     • Edit the configuration file /etc/default/tftpd-hpa to set the directory and options.
     • Start the TFTP service:

       sudo systemctl start tftpd-hpa

   • Connecting to a TFTP Server:

     • From a command-line client:

       tftp <server_ip>

   • Common Commands:

     • Upload File:

       put <local_file>

     • Download File:

       get <remote_file>

   Configuration Example: Configure the TFTP server to restrict access to a specific directory and ensure that it has read/write permissions.

   ---

   NTP (Network Time Protocol)

   Overview: NTP is used to synchronize the clocks of computers over a network. It operates on UDP port 123 and ensures that time is consistent across all devices.

   Basic Commands and Examples:

   • Installing and Configuring NTP Server on Linux:

     • Install ntp:

       sudo apt-get install ntp

     • Configure /etc/ntp.conf to set up NTP servers and access restrictions.
     • Start the NTP service:

       sudo systemctl start ntp

   • Synchronizing Time with an NTP Server:

     • On a Linux client:

       sudo ntpdate <server_ip>

     • On a Windows client:
       • Go to Date and Time Settings.
       • Select Add clocks for different time zones and Internet Time tab to synchronize.

   Configuration Example: Ensure that your NTP server configuration allows for accurate time synchronization and restricts access to trusted clients only.

   ---

   ICMP (Internet Control Message Protocol)

   Overview: ICMP is used for sending error messages and operational information about network conditions. It operates alongside IP and is crucial for network diagnostics and troubleshooting.

   Basic Commands and Examples:

   ping

   

   The ping command checks the reachability of a host on a network and measures round-trip time.

   • Basic Usage:

     • Linux/Windows:

       ping <host_or_ip>

     • Example:

       ping google.com

   • Specify Number of Packets (Linux):

     • Linux:

       ping -c 5 <host_or_ip>

     • Example:

       ping -c 5 google.com

     • This sends 5 packets and then stops.

   • Specify Packet Size (Linux/Windows):

     • Linux:

       ping -s 1000 <host_or_ip>

     • Windows:

       ping -l 1000 <host_or_ip>

     • Example:

       ping -s 1000 google.com

   • Specify Time To Live (TTL) (Linux):

     • Linux:

       ping -t 64 <host_or_ip>

     • Example:

       ping -t 64 google.com

   • Flood Ping (Linux):

     • Linux:

       ping -f <host_or_ip>

     • Example:

       ping -f google.com

     • This sends packets as fast as possible (use with caution).

   traceroute (Linux) / tracert (Windows)

   The traceroute command (Linux) and tracert command (Windows) trace the path packets take to a destination, showing each hop along the way.

   • Basic Usage:

     • Linux:

       traceroute <host_or_ip>

     • Windows:

       tracert <host_or_ip>

     • Example:

       traceroute google.com

     • Example:

       tracert google.com

   • Specify Maximum Number of Hops:

     • Linux:

       traceroute -m 20 <host_or_ip>

     • Windows:

       tracert -h 20 <host_or_ip>

     • Example:

       traceroute -m 20 google.com

     • Example:

       tracert -h 20 google.com

   • Show Numeric IP Addresses Only:

     • Linux:

       traceroute -n <host_or_ip>

     • Windows:

       tracert -d <host_or_ip>

     • Example:

       traceroute -n google.com

     • Example:

       tracert -d google.com

   • Use a Specific Network Interface (Linux):

     • Linux:

       traceroute -i <interface> <host_or_ip>

     • Example:

       traceroute -i eth0 google.com

   • Change the Default Packet Size (Linux):

     • Linux:

       traceroute -s 1000 <host_or_ip>

     • Example:

       traceroute -s 1000 google.com

       Connecting to or Listening on TCP Ports