This tutorial covers everything one like to know about networking basics including circuit switching vs packet switching, TCP/IP protocol fields, ARP/RARP protocol fields, what is IP address ,what is MAC address, networking devices which include hub, switch, bridge, router, gateway and firewall.

This page describes firewall basics, firewall types, firewall software and firewall hardware manufacturers.

• Circuit Switching vs Packet switching
• LAN vs WAN vs MAN
• What is an IP address
• What is MAC Address
• Basics of OSI and TCP-IP Layers
• What is Hub
• What is Switch
• What is Bridge
• What is Router
• What is Gateway
• Firewall basics
• TCP-IP Packet format
• ARP Protocol format

Firewall is a hardware and/or software which checks all the inbound and outbound packets from any system/LAN connected with internet mainly. This helps prevent any unauthenticated connection being established or prevent any spam/virus affecting the system/LAN. Different types of firewall exist which can have any one of the following type or it may include more than one combinations out of mentioned below.

Firewall types

Packet filter- This kind of firewall looks at each inbound and outbound packets and is called IP spoofing.
Application gateway- This kind of firewall operates at application layer and hence is applied to specific applications viz. FTP and Telnet based client-server applications.
Circuit level gateway- This kind of firewall is active during a TCP or UDP connection is being established. No check has been performed on packets passed between systems, once TCP/IP or UDP/IP based connection is established.
Proxy server- this kind of firewall basically checks all the packets/messages into and out of the LAN/network. This type of firewall works efficiently as it hides original/actual IP based network addresses. Many of the firewalls use two or more of the above mentioned techniques.

Firewall Software

Following are the firewall softwares available which help prevent our system from any unauthenticated attack.

1. COMODO Firewall
2. PC Tools Firewall Plus
3. ZoneAlarm Firewall
4. Ashampoo FireWall
5. Online Armor
6. Agnitum Outpost Firewall
7. Filseclab Personal Firewall Professional Edition
8. Sygate® Personal Firewall PRO
9. Symantec Norton Personal Firewall 2004
10. McAfee Personal Firewall Plus

Firewall Hardware manufacturers

Following are popular firewall hardware device manufacturers.

1. Cisco
2. ZyXEL
5. WatchGuard

RF and Wireless Terminologies