Forward Proxy vs. Reverse Proxy Servers

A forward proxy regulates client access to the internet, enhancing security and policy enforcement within an internal network. A reverse proxy, on the other hand, manages external requests to servers, offering load balancing and concealing server identities for added security. While forward proxies protect internal clients, reverse proxies safeguard servers from external access and threats.
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Forward Proxy vs. Reverse Proxy. What's the Difference?

A forward proxy acts on behalf of clients, controlling access to internet resources, enhancing security, and enforcing policies. Conversely, a reverse proxy serves on behalf of servers, managing requests from external clients, providing load balancing, and increasing security by concealing server identities. Forward proxies protect internal network clients; reverse proxies safeguard servers from external threats.

The primary purpose of a proxy service (the kind of service both provide) is to act on behalf of another machine. In our case, forward and reverse proxies aim to act on behalf of another machine — a client, web server, or other backend server. In this case, the proxy acts as a middleman.

The Forward Proxy

When people talk about a proxy server (often called a "proxy"), they often refer to a forward proxy. Let me explain what this particular server does.

A forward proxy provides proxy services to a client or a group of clients. Often, these clients belong to a shared internal network like the one shown below.

forward proxy

When one of these clients makes a connection attempt to that file transfer server on the Internet, its requests have to pass through the forward proxy first.

A request can be allowed or denied depending on the forward proxy's settings. If allowed, the request is forwarded to the firewall and the file transfer server. From the point of view of the file transfer server, it is the proxy server that issued the request, not the client. So, when the server responds, it addresses its response to the proxy.

But then, when the forward proxy receives the response, it recognizes it as a response to the request that went through earlier. And so it then sends that response to the client that made the request.

Because proxy servers can keep track of requests, responses, sources, and their destinations, different clients can send out various requests to different servers through the forward proxy, and the proxy will intermediate for all of them. Again, some requests will be allowed, while some will be denied.

As you can see, the proxy can serve as a single access point and control, making it easier for you to enforce authentication, SSL encryption, or other security policies. A forward proxy is typically used with a firewall to enhance an internal network's security by controlling traffic originating from internal network clients directed at Internet hosts. Thus, from a security standpoint, a forward proxy is primarily aimed at enforcing security on client computers in your private network.

But then, client computers aren't always the only ones you find in your internal network. Sometimes, you also have servers. When those servers have to provide services to external clients (for example, field staff who need to access files from your FTP server), a more appropriate solution would be a reverse proxy.

The Reverse Proxy

What is a reverse proxy? As its name implies, a reverse proxy does the exact opposite of what a forward proxy does. While a forward proxy proxy is on behalf of clients (or requesting hosts), and a reverse proxy proxy is on behalf of servers. A reverse proxy accepts requests from external clients for servers behind it, as shown below.

reverse proxy

In the example above, the reverse proxy is providing file transfer services. The client is oblivious to the file transfer servers behind the proxy providing those services. In effect, where a forward proxy hides clients' identities, a reverse proxy hides the identities of servers.

An Internet-based attacker would find it considerably more challenging to acquire data found in those file transfer servers than if he didn't have to deal with a reverse proxy. This is why reverse proxy servers like JSCAPE MFT Gateway are suitable for complying with data-impacting regulations like PCI-DSS.

Just like forward proxy servers, reverse proxies also provide a single point of access and control. You typically set it up to work alongside one or two firewalls to control traffic and requests directed to your internal servers.

In most cases, reverse proxy servers also act as load balancers for the servers behind them. Load balancers are crucial in providing high availability to network services that receive large requests. When a reverse proxy performs load balancing, it distributes incoming requests to a cluster of servers, all providing the same service. So, for instance, a reverse proxy load balancing FTP services will have a cluster of FTP servers behind it and will manage server load to prevent bottlenecks and delays.

Both proxy servers relay requests and responses between clients and destination machines. But in the case of reverse proxy servers, client requests that go through them commonly originate over TCP/IP connections. In contrast, in the case of forward proxies, client requests usually come from the internal network behind them.

Forward Proxy vs. Reverse Proxy Summary

This post discussed the main differences between forward and reverse proxy servers.

To keep it simple:

  • To protect clients in your internal network, put them behind a forward proxy.
  • If you intend to protect servers, put them behind a reverse proxy.

    Ready to enhance your network security and simplify your file transfer process? Explore how JSCAPE MFT Server can streamline your operations with a comprehensive managed file transfer solution. Schedule your free demo today and see how easy it is to set up forward or reverse proxies tailored to your needs.

Managed file transfer solutions such as JSCAPE MFT Server and MFT SaaS make it easy to set up proxy servers in your DMZ. Plus, JSCAPE can handle multiple protocols from a single server. This helps simplify your file transfer environment by enabling you to consolidate and manage all file transfers and trading partners from a single location.

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JSCAPE also provides broad functionality to help simplify and optimize your file transfer environment, including data loss protection, caching for HTTP/S content, and the ability to connect to virtually any web server with JSCAPE's REST API.