Overview

Introduction

The Understand Network Protocols - HTTP, HTTPS, NetBIOS, TCP, UDP module provides you with the instruction and computer hardware to develop your hands on skills in the defined topics. This module includes the following exercises:

  • Verifying Port 80 for HTTP
  • Verifying Port 443 for HTTPS
  • Verify Port 139 for NetBIOS
  • Understanding TCP and UDP
  • Using a Port Scanner

Exercise 1 - Verifying Port 80 for HTTP

Hypertext Transfer Protocol (HTTP) is application level protocol in TCP/IP that enables users of the World Wide Web to exchange data. HTTP supports a huge variety of data formats - from text to voice to all way through to multi-media. HTTP servers typically listen on TCP port 80 for any session requests from HTTP clients.

Exercise 2 - Verifying HTTPS Port 443

HTTPS, short for Hypertext Transfer Protocol Secure, is essentially HTTP with SSL/TLS added for security. The security feature helps prevent unauthorized access of information available on a network. This is especially relevant to networks accessed over WANs, such as Internet. TCP reserves port #443 for the HTTPS protocol.

Exercise 3 - Verifying Port 139 for NetBIOS

NetBIOS, short for Network Basic Input/Output System, is a communication protocol that supports communication among computers connected on LAN. NetBIOS does not support communication on WANs. Therefore, NetBIOS normally rides on TCP/IP when implemented on applications/computers connected to a WAN. Port #139 is reserved for NetBIOS protocol.

Exercise 4 - Contrast TCP and UDP Protocols

Both TCP (transmission control protocol) and UDP (user datagram protocol) are a part of the IP (Internet protocol) suite of protocols. Both these protocols convert data into packets to enable exchange across networked computers. However, the two are very dissimilar in their details of operation; and hence have very different application.

Exercise 5 - Using a Port Scanner

A port scanner is a software tool used for probing into local or remote systems to find out open TCP/UDP ports and collect system information like operating system type installed on the computer. This is used by system administrators to validate the security policy of firewalls and by hackers to determine the open ports on a computer that can be possibly exploited.

A wide array of port scanning software either free or subscription-based are available for public use. You can use a port scanning tool in a test lab environment. However, pre-caution must be observed when using this tool in a corporate network, as port scans normally trigger an alert when detected by firewall appliances.

In this exercise, you will learn about the following tool:

  • Network Scanner - Advanced IP Scanner

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