Firewalls were not the first, but it was one of the most prominent solutions that network developers have come up with since the prevalence of connected computing over the last few decades. Servers then are the network hubs. They are a primary point of communication that any connected device would require to communicate with. But which type of server can function as a firewall?
Proxy servers functionally act as a firewall by being a computer’s entryway to the internet. It is the medium that establishes the link and sets access rules to the one requesting the data (client), and the source of that data (website, local network, etc.).
Why can’t other types of servers function as firewalls? How do servers actually work as a security checkpoint? How easy is it to use for regular users? All answers to that and more are below.
Can a Server Act as a Firewall?
Depending on its primary purpose, a server can effectively function as a firewall. Firewalls are, after all, just a type of system that protects a localized network from potentially unauthorized access. Regardless of whether it is hardware-based, software-based, or even cloud-based (web-hosted). They just need a set of access regulations, a sort of rule set that would determine if incoming or outgoing data traffic is legit or not.
Servers are built in the same nature, acting as the very first access point available for a specific network. All other devices or sources within the network have to communicate with the server in order to send and receive information.
That being said, servers don’t exactly regulate incoming and outgoing communications the same way as dedicated firewalls do by default. Web servers for example, simply act as hubs when accessing websites. Mail servers without any modifications only store and send mail through their known client network.
The server needs to be configured specifically as a checkpoint, or as an additional security layer for the local network, before it can effectively act as a firewall.
Which Server Can Act as Firewall?
By nature of a server’s basic design, virtually any type can be configured into a firewall. That being said, there are at least four that can be considered the most “efficient”, at least when dealing with incoming data:
Proxy servers are dedicated systems (software or hardware) that function as a gateway between a local device and a target destination on the internet. Because they inherently function as an intermediary of data exchange between these two points, any user can simply modify authorization levels from the client side if it is intended to be used as a firewall.
For example, the end user’s IP address can be hidden from the target destination, or filter out unwanted external traffic directed towards the same client. Any data will have to sit first through the proxy server, and would never have to be directly passed onto the end user. All potentially malicious online entities can be filtered out.
This natural additional barrier to digital entry makes proxy servers the prime choice when setting up a server-type firewall.
File Transfer Protocol servers, as its name suggests, are servers that facilitate the transfer of stored files to clients that communicate its request. The main computer that acts as the FTP server provides its dedicated address to establish a link. The protocol then dictates the method of delivery and how confirmation of the data transferred is made between the client and server.
An FTP server is also a good choice to function as a firewall because like proxy servers, it acts as a separate layer that sets rules on what kinds of data are allowed to pass through. Users can also control which connections are accepted, and can easily be configured to reject the rest.
When modified correctly, only authorized clients would then be able to get unrestricted access, basically fulfilling what a firewall normally does.
E-mail servers handle the delivery of e-mail messages over the internet or specific network. It can sift through the sent data and process the communication channels in an instant so that the messages can be received by end-users in almost real-time.
While not as wide in its configuration as proxy servers, every e-mail still has to pass through multiple mail servers when being processed. This creates yet another layer of security for data transfer, as each mail server can establish its own set of rules for accepting certain e-mail formats, and determine which senders are legitimate.
Yet again, both such functions demonstrate capabilities that very much define how firewalls are supposed to control internet traffic.
Print servers simply manage multiple printers over a local computer network. The objective is to allow printers to print any document regardless of where the file is on the network. In other words, the file never needs to be locally saved in a machine, as any computer can communicate with any printer to initiate the print command.
The management of printers on a network is by itself already an act of access authorization control. But add the temporary transfer of files on the list, and we now again have a firewall-like setup.
After all, you don’t just want any computer gaining access to any files just because it is connected to the same print server. You also don’t want any printer to just print (process) any document that gets passed to it without proper network permissions.