An Introduction to Proxy servers and Firewalls

Proxy Server:

Proxy server is a server that acts as an intermediary for requests from clients seeking resources from other servers. A client connects to the proxy server, requesting some service, such as a file, connection, web page, or other resource, available from a different server.

Advantages Of Proxy:

Proxy Servers primarily provide anonymity on the Internet, since there is no direct connection between you and the Server.

Proxy Servers can be used for Regulating a Network and to apply Access Control Lists (ACL’s) on network services or content. For Example, It can be used to Block undesired sites.

Proxy severs can also be used use to Log the Internet usage of the Users in a Specified Network.

Proxy Servers can also provide some features which are generally Found in Firewalls and Intrusion Prevention Systems such as scanning the transmitted content for Malwares before delivery.

Proxy Servers are also used to scan outgoing traffic to prevent data leakage.

Types of Proxy servers

•Caching Proxy Server

•Web Proxy Server

•Content Filtering Server

•Anonymizing Proxy Server

•Hostile Proxy

•Transparent Proxy server

•Reverse Proxy


What is Packet Filtering?

Packet filtering is a process of Passing data Packets through a network Interface based on Source and Destination addresses, ports, protocols, keywords or URL’s.

During Packet filtering, the packet filter (software or hardware) normally would not look into the headers of the packets but instead it checks the Body of the Packets against the Security Policies implemented for the outgoing traffic.

Packet filtering is normally used in combination with a firewall. Today, Latest firewalls are being made with the capability of packet filtering pre-installed.

Difference between Proxy Server & Firewalls

Firewall-

Firewalls work on Packet level, it can apply rules on packets (by checking source/destination protocol/port) to decide whether the packet will be forwarded or denied.

If we disable the firewall, then anybody can access anything from internet, and the network will be unrestricted.

Proxy

Whereas, proxy server works on application level and applies ACLs for URLs and Keywords to decide whether the packet will be forwarded or denied.

But in case of Proxy Server, if it if disabled, the Traffic going through it would cease and all requests would become un-reachable.

Hope you liked it. I will write articles on bypassing firewalls/proxies in my next tutorial.