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Abstract :
Network security can be described as the effort to create a secure computing platform, designed so that agents (users or programs) cannot perform actions that they are not allowed to perform, but can perform the actions that they are allowed to. Network Security systems insure the integrity of the system by protecting from hackers trying to get into the system and by restricting access within the system to individuals specific needs.
We have dealt with one of the Basic Network Security Tools the Firewalls. It is a combination of hardware and software that secures access to a local network or computer. A firewall guards the local network by analyzing the data leaving and entering, allowing authorized traffic through while keeping unauthorized traffic out.
Firewalls are typically configurable by network administrators so that they can set policy to determine what traffic is deemed safe. A firewall is simply a program or hardware device that filters the information coming through the Internet connection into your private network or computer system. Firewalls use one or more of three methods to control traffic flowing in and out of the network: packet filtering, proxy service, and stateful inspection.
Firewalls are customizable (add or remove filters) through IP address, protocols, domain services etc. They protect the network from SMTP session hijacking, denial of service, spam, viruses, e-mail bombs etc. A function that is often combined with a firewall is a proxy server. The proxy server is used to access Web pages by the other computers.
Hence we conclude that Network Security has become a mandatory thing for every network to such an extent that we can’t imagine a world without it in future.
Introduction:
Network is medium for communication. Security has become a mandatory thing for every network .To protect these networks from attacks (that may be internal or external) security must be provided. It can be provided through secure network devices like firewalls.
What is Network Security?
Network security can be described as the effort to create a secure computing platform, designed so that agents (users or programs) cannot perform actions that they are not allowed to perform, but can perform the actions that they are allowed to. Network Security systems insure the integrity of the system by protecting from hackers trying to get into the system and by restricting access within the system to individuals specific needs.
We have dealt with one of the Basic Network Security Tools the Firewalls.
What is a Firewall?
A system designed to prevent unauthorized access to or from a private network. Firewalls can be implemented in both hardware and software, or a combination of both. Firewalls are frequently used to prevent unauthorized Internet users from accessing private networks connected to the Internet, especially intranet. All messages entering or leaving the intranet pass through the firewall, which examines each message and blocks those that do not meet the specified security criteria.
Firewalls make it possible to filter incoming and outgoing traffic that flows through your system. A firewall can use one or more sets of ``rules'' to inspect the network packets as they come in or go out of your network connections and either allows the traffic through or blocks it. The rules of a firewall can inspect one or more characteristics of the packets, including but not limited to the protocol type, the source or destination host address, and the source or destination port.
Firewalls can greatly enhance the security of a host or a network. They can be used to do one or more of the following things:
• To protect and insulate the applications, services and machines of your internal network from unwanted traffic coming in from the public Internet.
• To limit or disable access from hosts of the internal network to services of the public Internet.
• To support network address translation (NAT), which allows your internal network to use private IP addresses and share a single connection to the public Internet (either with a single IP address or by a shared pool of automatically assigned public addresses).
After reading this chapter, you will know:
• How to properly define packet-filtering rules.
• The differences between the firewalls built into FreeBSD.
• How to use and configure the OpenBSD PF firewall.
• How to use and configure IPFILTER.
• How to use and configure IPFW.
Before reading this chapter, you should:
• Understand basic FreeBSD and Internet concepts