The firewall protects a network from malware or hackers to an external network. The firewall filters potentially harmful traffic entering or leaving. Firewalls are the Member States within the networks on the Internet. It also protects computers. The five, the deployment of firewall packet filter, application filters, proxy servers, circuits and Stateful Inspection.

• Packet Filtering: A firewall packet filtering, each packet of the conversion of the unit. It also controls the packet headers of all packets on the network firewall.

Source IP Address: It is the host of the suite. Striker of this area can be in an attempt to IP spoofing of conduct. Firewall is configured so that packets that arrive at the external interface or an error in the host or the attempt to IP spoofing. Objective of the IP address: This is the IP address that tries to achieve.

IP-ID: Each IP is a protocol that follows. For example, TCP (Transmission Control Protocol), Article 6, UDP User Datagram Protocol) Article 17, and Internet Control Message Protocol (ICMP) is ID-1.

Fragmentation Flags: firewall, review and transfer or deny packets fragmented. The success of a fragmentation attack can allow an attacker to packets which could be an internal host.

IP Configuration Options: This field is used for diagnosis. The firewall is for submission of packets on the network, in relation to this area. Hackers can in this area, in conjunction with IP spoofing to redirect the network packets to select.

• Apply filters: This property allows listening connections and conducts safety inspections. The firewall acts as a proxy for connections between the internal and external network. The firewall rules on monitoring access to certain applications. It is also for e-mail virus installations. These firewalls are often considered as E-mail gateway.

• Proxy Server: A proxy server takes the responsibility for the provision of services between the internal and external network. Proxy server can be used for the diagram of the address space of the internal network. It can also be used for applications based on the protocol and address.

• Circuit level: a control circuit on the firewall ports TCP and UDP, but do not watch the data on them. If a connection is established, the traffic is, without further consideration.

• Stateful Inspection: A firewall, control of the network layer. It evaluates the information in IP header. It also monitors the status of each connection. The links are rejected when they try to take measures which are not standard protocol. The firewall features can be referred, together with an application firewall. A lot of series firewall is a common practice to improve security in the perimeter network.