Most people have heard about firewalls, whether from movies or real life experiences. Proxy servers are still a bit of a mythical concept to most. Yet, in some sense, both a firewall and a proxy server are very similar.
On the other hand, both a firewall and proxy server can do entirely different things. Both provide security against network threats, but the former only blocks unauthorized access attempts while a proxy server sits as a mediator between a computer and the internet. It may sound confusing at first, but we will be doing our best to clear up all the mystique surrounding these two concepts.
What is a proxy server?
Proxy servers are essentially half-way points for internet traffic. Instead of sending network traffic directly to the destination, devices first send it to a proxy server, which then relays the information to the intended target. In the end, the source of the request is masked.
Proxies, however, are simply other machines. They may be household devices or servers in datacenters. Like any other machine, they have an IP address and assigned port numbers, both of which are used to connect to the proxy server.
In short, users first connect to the proxy server, which then connects to the destination server. As a result, it almost always thinks that the proxy server is the original connection source. A few important goals are achieved in this manner.
First, a proxy server limits the amount of data that can be acquired by the destination server. For example, the real IP address, outside of security exploits, won’t be revealed. Other data is harder to gather as well, making it a lot more difficult to track the user.
Proxy servers provide some measure of security through obfuscation. Since IP addresses are not revealed, gaining access to the machine isn’t easy. Of course, malware and other threats can still affect the original machine. But in these cases, both a firewall and proxy server can be bypassed.
Additionally, since a proxy server always has its own IP address, it has a perceived geographical location as well. Therefore, if a proxy server is a machine somewhere in Spain, it will seem that the connection is coming from that country. In turn, these geolocation changes can be used to improve anonymity and to access restricted content.
Finally, proxy servers, unlike some other connection intermediaries (e.g. VPNs), can be used to divert only application-specific traffic. In other words, if a proxy server is required only for a small part of the traffic coming out of a machine, it’s possible to narrow down their application.
Where proxies are used?
While network security is not the only use for a proxy server, it does play a formidable role in it. In fact, a firewall and proxy server can be combined to create a proxy firewall. While they are common, the use cases do not end here.
It can be used for numerous non-cybersecurity related applications. For example they are frequently used for automated data acquisition processes (i.e. web scraping). In turn, data acquired through proxies is used for other purposes such as price monitoring.
Yet, they remain a force to be reckoned with in cybersecurity. Regular companies may use a proxy server for email protection. Any email arriving to the confines of the internal network is scanned and a proxy server is used to visit outbound links. That way, emails are checked for malware and phishing links automatically.
Additionally, cybersecurity companies can use proxies for load testing. For most companies, servers need to stay up 24/7, but a large amount of traffic can bring them down.
While it usually happens naturally, unauthorized users can sometimes attempt to use a large amount of traffic to bring services down. In order to prevent that, cybersecurity companies schedule performance tests with a large amount of proxies to discover weak points in the infrastructure.
Finally, a proxy server can be used not only for local network tests. Since they are used for automated data collection, cybersecurity companies can utilize them for similar purposes. They frequently scan the entire internet to discover malicious entities infringing upon intellectual property or sharing data from leaks and breaches.
What is a firewall?
As mentioned above, a firewall and proxy server are similar, but do have their own important differences. Both are used for network security. Firewalls, however, are much more essential and are pretty much used only for that purpose.
Unlike a proxy server, however, a firewall works by blocking or allowing access to a machine through numerous means. There are no IP address changes involved (like with a web proxy).
Additionally, a firewall may be established on pretty much every possible level of computing. They can be implemented on a hardware and software level. They can be used to protect users on a public network or a private network. Essentially, they are more or less ubiquitous wherever public networks exist.
Since it’s meant to protect against network-based attacks, a firewall, simply put, filters data. It’s implemented through several methods, but all of them are intended to prevent those that try to gain unauthorized access to the machine.
How does a firewall work?
Firewalls can be separated into 4 primary types, each of which involves network protection. These types are: packet filtering firewalls, circuit-level gateways, application-level gateways, and UTM firewalls.
Packet filtering
These are the traditional firewalls we all know and love. They are implemented on the network layer and work by checking incoming packets. Data packets, simply put, are messages sent from one machine to another.
A data packet, however, contains more than the message (also known as the payload). A header is sent with each packet that has some metadata such as IP addresses of both the source and destination, port number, etc.
Packet filtering firewalls allow the implementation of rules that forbid or allow only certain types of headers to be passed on to the machine. If a header contains forbidden content (or does not contain permitted content), the packet is dropped and such an event is logged on the machine.
Circuit-level
These firewalls work on the session layer through the standard TCP/IP connection. Essentially, whenever a machine and a server connect, they exchange a handshake to confirm legitimacy. Circuit-level firewalls check these handshakes to protect against malicious attacks.
While they are extremely resource-efficient, they have no further protections. Circuit-level gateways offer no protection once a handshake is established. They do not check the contents of IP packets. If a connection is established, a malicious user can attack the machine on the IP packet level and bypass security.
Application-level
These are the proxy firewalls, which work on application and transport layer data. In other words, they work as a combination of packet filtering and circuit-level firewalls with some additional protection. As a result, the protection offered by application layer firewalls is often greater than any of the two alone.
They also provide fairly extensive logging and inspection capabilities, making it easier to perform data analysis and uncover possible issues. Additionally, since a proxy server is in use, they have their own IP and offer some anonymity.
Unfortunately, since it’s a multi-layered firewall that inspects both the handshake and the IP packets, it adversely affects network performance. Depending on usage that might make a proxy server based firewall less preferable.
Additionally, private users will usually have to acquire a proxy server in order to operate an application layer firewall. They could also choose to get a provider that grants the entire package of a firewall and a proxy server. In both cases, however, costs are increased.
UTM firewall
UTM (or Unified Threat Management) firewalls are the most advanced type of software. Truly, it’s not even a single piece of software. UTMs are usually packages that can include a firewall, proxy server, anti-virus, etc.
As they are unified, the security overhead generated is nearly complete. That makes them the preferred options for small-to-medium businesses as UTMs are offered by third party providers that take care of deployment and integration.
Unfortunately, they cannot provide the customization that might be necessary for larger businesses with more varied use cases. Additionally, that creates an additional security risk as it makes the buyer dependent on the third party.
Proxy server vs firewall: quick rundown
- Monitors all incoming and outgoing traffic on any local network
- Blocks illegitimate access attempts (such as IP spoofing)
- Filters data based on packets, IPs, or handshakes
- Involves network and transport layer data
- Protects internal networks from attacks
- More overhead
- Connects to an external client and communicates with a server
- Facilitates connections over a network
- Filters requests that are made to connect to the network
- Works on an application level
- Used for anonymity and to bypass restrictions
- Less overhead
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