A[FONT=Lucida Sans Unicode, sans-serif]n application layer firewall is a type of firewall which controls the input, output and access to from or through any application or service. The application program that runs on the application layer firewall system is known as application proxy or application level proxy or application gateway. When a client program (or any software that runs on the user's computer) initiates a connection to a destination service, it connects to the application gateway or proxy. Once connected, the proxy does not permit direct connection from Internet to your server and perform elaborate sorting and reviewing of the traffic that passes through them to the server. The application level proxies can inspect the packet or traffic content and check for inconsistencies, malicious commands and executable programs. Since all communication is conducted through the proxy server, computers behind the [/FONT][FONT=Lucida Sans Unicode, sans-serif]firewall[/FONT][FONT=Lucida Sans Unicode, sans-serif] are protected.[/FONT]
[FONT=Lucida Sans Unicode, sans-serif]Application proxies can either be transparent or non transparent which is a matter of implementation and address hiding rather than security. In former, the application proxies will be transparent to the client and server and does not require any special client or server configuration. In non transparency, the client and server can address the proxy server directly. Application-level proxies are application-aware and thus effortlessly deal with complex protocols used for video conferencing, VoIP etc. [/FONT]
[FONT=Lucida Sans Unicode, sans-serif]Unlike application layer firewall, both stateful firewall and packet-filtering firewall are susceptible to application layer attacks. These traditional filtering techniques analyze the ports, protocols and states of the packets but do not entirely disassemble each packet and analyze the content carefully which has lead to application layer firewall[/FONT].
[FONT=Lucida Sans Unicode, sans-serif]Application proxies can either be transparent or non transparent which is a matter of implementation and address hiding rather than security. In former, the application proxies will be transparent to the client and server and does not require any special client or server configuration. In non transparency, the client and server can address the proxy server directly. Application-level proxies are application-aware and thus effortlessly deal with complex protocols used for video conferencing, VoIP etc. [/FONT]
[FONT=Lucida Sans Unicode, sans-serif]Unlike application layer firewall, both stateful firewall and packet-filtering firewall are susceptible to application layer attacks. These traditional filtering techniques analyze the ports, protocols and states of the packets but do not entirely disassemble each packet and analyze the content carefully which has lead to application layer firewall[/FONT].
