Firewalls

What is firewalls?

Firewalls can be a hardware or software that provide protection to computers and networks. It was a choke point of control and monitoring the computer and networks. It provide restriction on network services for authorized traffic is allowed to access the services. It also is a auditing and controlling access of the devices to use the network resources, which can implement alarms for abnormal behavior.


Normally, Firewalls provide 2 basic functions:
1) Packet filtering - Allows or denies transfer of packets based on security policy rules.
2) Application Proxy gateway - Provides network services to users within the firewall

Firewall Features

• Logs access (authorized/unauthorized) in and out of a network
• Establish a Virtual Private Network (VPN) link to another computer
• Secures host Within the network to prevent attackers intrusions
• Filter inappropriate content such as executable mail attachments
•  Securing Individual Users:
• Provides anti-virus programs that alerts users on detecting e-mail attachment or file containing virus.

Firewall Limitation

• Cannot protect from attacks bypassing it 
• eg sneaker net,utility modems, trusted orgranizations,trusted services (eg SSL/SSH)
• Cannot protect against internal threats
• eg disgruntled employee
• Cannot protect against transfer of all virus infected programs or files because of huge range of O/S & files types.