1. Firewalls By Bhupendra Ratha, Lecturer School of Library and Information Science Devi Ahilya University, Indore Email: bhu261@gmail.com bhu261@gmail.com

2. What is a Firewall? A firewall is either a software system or hardware system or combinational system that enforces an access control policy between two networks. Thus, a firewall is the manifestation of our security policy. A firewall is either a software system or hardware system or combinational system that enforces an access control policy between two networks. Thus, a firewall is the manifestation of our security policy. Generally speaking, a firewall is a protection device to shield vulnerable area from danger network. Generally speaking, a firewall is a protection device to shield vulnerable area from danger network.

3. Cont…

4. Cont… A firewall's function within a network is similar to firewalls in building construction, because in both cases they are intended to isolate one "network" or "compartment" from another. However, network firewalls, unlike physical firewalls, are designed to allow some traffic to flow. A firewall's function within a network is similar to firewalls in building construction, because in both cases they are intended to isolate one "network" or "compartment" from another. However, network firewalls, unlike physical firewalls, are designed to allow some traffic to flow.

5. Types of Firewall Network layer firewalls Network layer firewalls Application-layer firewalls Application-layer firewalls

6. Network layer firewalls Network layer firewall guards the entire network from unauthorized instruction. An example of a network layer firewall is packet filtering. Which simply reviews all information coming into a network and reject the data that does not meet a predefined set of criteria. Network layer firewall guards the entire network from unauthorized instruction. An example of a network layer firewall is packet filtering. Which simply reviews all information coming into a network and reject the data that does not meet a predefined set of criteria.

7. Application-layer Firewalls It controls access on an application-by-application basis. For example, proxy server can be set up to permit access to some applications, such as http. It controls access on an application-by-application basis. For example, proxy server can be set up to permit access to some applications, such as http.

8. Limitations of Firewalls The firewall cannot protect the resources from attack by an internal user. The firewall cannot protect the resources from attack by an internal user. A firewall is useful only if all the internet traffic is handled through the firewall. A firewall is useful only if all the internet traffic is handled through the firewall. Typically a firewall cannot protect a private network from external viruses. Typically a firewall cannot protect a private network from external viruses.

9. Some firewall products Smartwall Smartwall The norman firewall The norman firewall Fire door Fire door Alta vista firewall Alta vista firewall Netlock Netlock