Brief Information about Firewalls and Firewall Implementation
Internet has the ability to connect different computers in different networks. It is a collection of networks. Most of the corporate networks contain information that is very confidential such as trade secrets, financial analysis, etc. The information which is kept of the network should not be disclosed to its competitors. Thus, security is needed for the information kept in the network to protect it from unauthorized access. In addition to this problem, digital viruses, digital pests can destroy this important data in the network.
Therefore, we need to provide middle-level security, that has the strategy of accepting data without errors and discarding that which contains errors. One such method is by using encryption. However, this method protects the data from wiretapping during transmission but does not keep it away from unauthorized access or from viruses. in order to overcome these problems, firewalls were implemented. Network firewalls provide a barrier between networks that prevent or denies unwanted or unauthorized traffic. It is a system or group of systems used to control access between two networks. Trusted network 2. Untrusted network. Using pre-configured rules or filters.
Firewalls can be composed of a single router, multiple routers, a single host system or multiple hosts running firewall software. Firewalls are used to provide security to corporate networks. This design permits only one way to enter the network and leaving the network. It is called an electronic bridge between the networks.
The configuration contains two components. They are
- Packet filtering routers.
- Application gateways.
Packet Filtering Routers
They are used for checking the incoming and outgoing packets. The packet filtering process is accomplished when each packet passes through, the firewall, it is examined and information contained in the header is compared to a pre-configured set of rules or filters. Each packet is examined individually without regard to other packets that are part of the same connection. Packet filters are the standard routers with additional functionality to inspect the packets and if packets don’t meet some criteria then these packets are discarded. Incoming packets are checked using outside packet router, and outgoing packets are examined using inside the packet router.
2. Application Gateways
In between, the application gateway is used to examine the messages going in or out. It also contains an anti-virus tool which can be used to discard the packets, if it detects any virus.