What's the difference between proxy and firewall?

Question

What's the difference between proxy and firewall? And can we integrate a nat or pat into a proxy or firewall?

Solution 1

A Proxy Server is a device that:

acts as an intermediary for requests from clients seeking resources from other servers.

A Firewall is a device that is:

designed to permit or deny network transmissions based upon a set of rules

The former just lets all traffic through regardless of source or destination and is a way of routing requests through known gateways and is often used to allow companies to log network traffic for example.

A proxy may include a firewall as part of it's functionality but it doesn't have to.

I would expect that Network Address Translation (NAT) and Port Address Translation (PAT) - which is basically the same thing - would be functionality that could be built in, but NAPT is more used on routers etc. to:

However it is common to hide an entire IP address space, usually consisting of private IP addresses, behind a single IP address (or in some cases a small group of IP addresses) in another (usually public) address space.

Solution 2

Proxies are used explicitly, for example a browser is configured to forward http requests to a proxy. A firewall is used implicitly, for example to drop some network connections. NAT works at the network level. NAT uses the same mechanisms as a stateful firewall to let a few machines appear with a single external IP address. Conceptually that makes NAT closer to a firewall. On the other hand the fact that a NAT rewrites packets (changing ports and addresses) is similar to a proxy changing ports and addresses and adjusting headers before relaying a request.

Solution 3

And can we integrate a nat or pat into a proxy or firewall?

Yes, Microsoft's Threat Management Gateway (TMG) is an example of a proxy & firewall wrapped into one.

Comments

[samia]

ok! can we integrate a nat/pat into a proxy or firewall?

[ChrisF]

@samia - probably, but I'm not sure what "pat" stands for.

[Matthew]

Hi uSlackr - could you revise answer to explain the differences?

[Matthew]

@Chris - pat is port address translation.

[ChrisF]

@Matt - cheers.

[samia]

@Chrisf (Port Adress Translation) like a nat(Network @ Transltion) used to associate a public adress to private ones to allow access on internet! becoz in our machines we have private @ and to access internet we need a public one!!! That's why a nat/pat are used for ;)

[Rory Alsop]

@samia - you don't need PAT as such. NATing will do what you need with almost all firewall scenarios

[MaQleod]

NAT/PAT is something a router does, not a proxy or firewall. A firewall can block and open ports, the router actually does the traffic direction that you see with NAT/PAT.

[samia]

@Rory: sorry but having a nat in such company is not enough to translate all private @!I think we need a pat to identify the location of a node in a network using its port otherwise when receiving a msg to send it to an x internal machine a nat cannot identify the destination??? If i'm wrong say to me please!

[Rory Alsop]

Unless you have a very strange port lockdown on your machines NAT will absolutely do what you need. PAT is more for when you have a specific port restriction, but not commonly used the way you are describing

[samia]

thank u! How to make an internal or a private network more secure, efficient and functional? Do we have to configurate all these equipmnt : PAT/NAT,Proxy,Firewall...???

[samia]

I can't underestand what you mean? could u pleaz repeate what's the difference between these 2 eqpmnt that you see?

[Tobu]

@Xenoactive This kind of thing needs a different name. The HTTP spec defines proxies as used explicitly, and transparent proxies as proxies that don't alter the requests at all.

[Matthew]

good point, I will change the vote.