Let’s skim through proxy servers !

What exactly is a proxy server ?

To begin with — what is a proxy ? It’s someone that has the authority to do some act on your behalf. Remember proxy attendance in school ? I’m pretty sure you did it for a friend or two in school & then the professor caught you & then … fun times haha !

So then what’s a proxy server ? It’s basically a computer on the internet — let’s call it computer A whose IP address is known by you or anyone who is sending the request to another computer B. So this computer A will make a request to computer B on your behalf , collect the response and send it back to you! That’s it!

Now there is a forward proxy and a reverse proxy.

What is a forward proxy ?

Forward proxy & proxy is the same thing. It’s used interchangeably. It is used by client on the client side eg: web browser. They are used to control traffic that leave the network. If you are at work on the corporate network and try to access say instagram or facebook or Netflix and you can’t access such sites — that would be because of the forward proxy. It sits between user and the internet.

What are the benefits of this forward proxy ?

• caching — detailed post about caching coming soon ..
• acts as a firewall
• helps manage all requests at one place
• security — prevents from cyber attacks etc , encryption decryption of the request that goes through , IP addresses are masked

Examples of forward proxy:

• TOR (The Onion Router)

What is reverse proxy ?

Same idea as forward proxy but on the server side instead! It protects the server instead of protecting the client. So if there is any request that comes from the internet that wants to hit any of your servers it would hit the reverse proxy first and then that reverse proxy would decide how to forward that request to the servers.

What are the benefits of reverse proxy ?

• Pretty much same as the forward proxy but additional feature is load balancing — article on that coming soon !
• helps in compressing requests that are going from the network to and fro thus reducing the bandwidth.

Examples of reverse proxy:

• nginx is usually set up as a reverse proxy — separate article coming soon !

Which layer of the OSI model do proxies work on?

Most of the time the proxy concept refers to application layer or layer 7 which is most common though they do work on layer 4 & above. But some operate on layer 3 as well which is known as NAT ie network address translation.

Now you might ask what is the difference between a reverse proxy & a load balancer ? Reasonable question ! Simple answer is that:

• load balancer is a reverse proxy by definition! But it has a more specific purpose in terms of handling giant loads due to heavy requests.