Despite their common name, forward and reverse proxies couldn’t be more different in terms of their purpose, implementation, and the role they play in enterprise architectures.
The main difference between a reverse proxy and a forward proxy is that a forward proxy allows computers isolated on a private network to connect to the public internet, while a reverse proxy allows computers on the internet to access it on a private subnet.
What are forward proxies and reverse proxies?
Professional businesses, such as banks and insurance companies, and government agencies often place office computers used by corporate employees on a single, isolated, private network. This isolation protects corporate computers from outside attacks. It also restricts the ability for users to move data and files out of the protected subnet in nefarious ways.
However, it is almost impossible for employees in a modern workplace to do their job without some access to the internet. This is where the forward proxy comes into play.
A forward proxy accepts connections from computers on a private network and forwards those requests to the public Internet. It is the single point of exit for subnet users who want to access resources outside of their private network.
As the name suggests, a reverse proxy is the opposite of a forward proxy. The reverse proxy acts as a central entry point for external systems to access resources on a private subnet.
In an enterprise architecture, a reverse proxy acts as a public access point for users to access data and information stored on servers located on a private, isolated subnet.
For example, when users want to check their account balance, the bank’s login page is served by a web server acting as a reverse proxy. When users submit their username and password, the request goes back to the web server, which acts as a reverse proxy, sending the request through authentication servers, application servers, and database servers located behind different firewalls on isolated private networks. The reverse proxy then constructs a response based on the data returned from the servers located on the private subnet and sends that response back to the client on the public internet.
Reverse and forward proxy similarities
The main similarity between a forward and reverse proxy is that both protect devices connected to a private network from threats coming from the internet and other external networks.
Both forward and reverse proxies can restrict the types and sizes of files that pass through them and prohibit unauthenticated users from sending requests.
Both forward and reverse proxies can perform port and protocol switching, which can further obfuscate the access patterns used to access resources hidden behind them.
It is also possible to configure both a forward and reverse proxy using the same software.
For example, Nginx and Apache web server are both commonly used as reverse proxy in enterprise architectures. These two software components can also be configured to act as a forward proxy.
Reverse and Forward Proxy Differences
Despite the many similarities, the way an organization implements a forward proxy differs significantly from a reverse proxy.
A forwarding proxy is typically configured on an office worker’s laptop or desktop to provide secure access to the public Internet, whether at work locally or remotely logged into the private network. In addition, the forward proxy must be configured manually. Any computer that wants to access resources outside of the workstation’s private subnet must be configured with the IP address and port number of the network’s forwarding proxy.
In contrast to the forward proxy, a reverse proxy does not require any preconfigured clients. The reverse proxy server is publicly accessible.
A reverse proxy and a forward proxy both serve a common purpose in enterprise architectures: facilitating resource requests between private networks and the public Internet. However, they perform drastically different functions and serve decidedly different customers.
Forward proxies help users on a private subnet access the public internet. A reverse proxy allows requests from the public internet to access resources that are on an otherwise private subnet.