Firewall vs Proxy Server
Firewalls and Proxy servers are both popular mechanisms for applying security measures by using restrictions on transmissions on networks. A device or set of devices intended to allow permission to accept/deny transmissions based on a certain set of rules is called a firewall. Firewall is used to protect networks from unauthorized access while permitting legitimate transmissions to go through. A server that acts as an intermediate interface between the clients and other networks (including the internet) is called a proxy server.
A Firewall can be implemented in both hardware and software. Software-based firewalls are a common place in many personal computer operating systems. Moreover, firewall components are contained in many routers. Conversely, many firewalls can perform functionality of routers as well. There are several types of firewalls. A Packet filter, as the name suggests, looks at packets entering or leaving the network and accepts or rejects based on the filtering rules. Firewalls that apply security mechanisms to specific applications, such as FTP and Telnet servers are called Application gateway proxies. Circuit-level gateway applies security mechanisms when UDP/TCP is used. A Proxy server itself can be used as a Firewall. Since it can intercept all messages entering and leaving the network, it can effectively hide the true network address.
When it comes to Proxy servers, they will typically evaluate a request from a client for a file/web page or any other resource, according to its filtering rules based on different criteria such as IP address or protocol. If the request is granted, the proxy will contact the actual server hosting the resource on behalf of the client. Sometimes a proxy server may maintain a cache, so that some client requests can be satisfied without actually communicating with the actual server. Furthermore a proxy server can alter the client’s request or the server’s response depending on the requirements of the network restrictions. Most proxies allow access to the World Wide Web and they are called Web proxies. A proxy server may have a large range of purposes, including, maintaining security by keeping its clients anonymous, providing fast access to resources by maintaining a cache, blocking undesired sites by applying access policy to network service or content and providing Internet usage report for companies by logging/auditing usage of employees. Furthermore, they can be used for bypassing security controls, scanning transmitted content for malware or outbound content and circumventing regional restrictions. If a proxy server passes communication both ways without modification it is usually called a gateway. A proxy server can be placed between the user and the server at various points including the user’s local computer.
So, it is clear that both Firewalls and Proxy servers are seemingly similar because they both apply security measure for networks, but they do have their differences. Usually Firewalls act in packet-level whereas proxies work at much higher levels such as the application layer of the network. Furthermore, by disabling the firewall, usually the LAN would have full Internet access, but if you disable the proxy server, there is no way to connect to the Internet.