Understanding Common Ports and Protocols

Introduction

The Understanding Common Ports and Protocols 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

Exercise 1 - Verifying Port 80 for HTTP

HTTP, short for Hypertext Transfer Protocol, enables the 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

Hypertext Transfer Protocol Secure (HTTPS) is essentially HTTP with SSL/TLS added for security as it encrypts HTTP traffic with the use of computer certificate. The certificate is issued by a service called Certification Authority (CA). The CA can be internal service of an organization or it could outsourced from a commercial provider.

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.