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What's a Proxy Server?

When I configure various internet applications, they often ask
for something called a “Proxy Server”. I’ve apparently never needed it, since
everything seems to work without configuring a proxy server. But does have me
wondering – just what is a proxy server?

A proxy is a stand-in for you – someone who does something on your behalf. A
proxy server is a kind of stand in for your computer.

The questions that raises of course would be how, and … why?

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A good example, and the one you probably see the most, is a web proxy. When
configured to use a proxy, your web browser contacts the proxy server for each
web access instead of going directly to the target server on the internet. The
proxy server then turns around and makes the “real” request of the web server.
The proxy server gets the response, and then passes it back to you.

So why go through that extra layer?

A proxy server is designed to understand, and act on the data that’s going
across it. For example a company’s web proxy server might be where access to
certain sites is blocked. It might track the surfing activities of employees or
scan the returned web pages for viruses.

A proxy also hides the computers behind it. For example a company’s web
proxy may look like only one or two machines to the outside world, but in fact
there may be several hundred employees surfing the web through it.

Proxy servers can also cache data. If everyone behind a proxy is requesting
the same data over and over again, a proxy might elect to keep a local copy,
and not bother getting it from the internet for every request.

Since you might also be wondering, some of the functions of a proxy are
similar to a NAT router or a firewall. The biggest of several differences is
that a proxy server actually understands the data that it’s acting on. NAT
routers and firewalls typically only understand details of where the data is
going to or coming from, but not what it contains.

As you’ve already noticed, in most cases proxy servers are not used by
typical internet users. There are certain situations … usually corporate, and
certain ISPs that require their use. The good news is that it’s uncommon enough
that if you do require it, it should be part of the setup information
provided by your company or ISP.

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38 comments on “What's a Proxy Server?”

  1. hi,
    i just want to ask you to tell how to use a proxy server to fool a firewall. i mean how to use it so that i can access all the sites i want from my work palce for example?

    Reply
  2. Hi, I got a question…
    What is proxy traffic? I was reading some search engine forums and they said that “proxy traffic” is “bad”…and that some of them block proxy traffic… how’s that? how can you tell? what is it?
    Thanks a lot, most useful site…

    Reply
  3. MSN messenger will no longer load on my computer because it says “Your Proxy Server appears to be offline, or your proxy settings are invalid” how do I fix this situation as I have tried many things. Please help. Thanks

    Reply
  4. My msn keeps coming up with a troubleshoot window everytime i try and login in msn and it says it could be due to improper proxy or firewall settings can someone pls email me and tell me what this means and how i can just get msn back bcos i have tried many things and nothing worls that i hav tried. thnx

    Reply
  5. By connecting through a proxy server does that mean that my ISP will only be able to traceroute my surfing activity up to the proxy server ?

    thank you

    Reply
  6. i have a question i didnt find anywhere yet, how do i change my proxy? because i have to use a US proxy to view a video on the web and i cant watch it here in canada 10 miles away from us line…silly. anyway
    thank for helping me!

    Reply
  7. if i am behind a proxy server..such as in a university lan…then if i access my email such as hotmail….are my emails being stored on the proxy server…and can someone actually go through them later on???

    Reply
  8. It says my proxy server is offline when i try to log in.
    Then it says take the test to see if your able to actually connect to the internet.
    It then says, you can now successfully sign in to msn.
    But doesnt.
    Nothing works all because of this proxy server setting.
    Can you please tell me how to fix this thing?
    thanks.

    Reply
  9. You can see what proxies you have by typing ‘tracert 154.178.143.145’ in DOS. Or you can use ‘tracert http://www.address.com‘ A handy wee tip I read about in a PC magazine once along with ‘ping’. Good stuff to know.

    Reply
  10. My friend said that I could enter blocked sites in my country if I change my proxy server to a foreign country’s one? Is that true?

    Reply
  11. you gata help me. each time i go to gaiaonline.com it says im goin tof ast and i think it thinks im a bot. i went on help rooms and some girl bipassed it by using a proxy server (the gaia problem is getting very common) but pleas tell me how to download the proxy server to bipass it or find out how i can play gaia without downloading the proxy server. whatever you do, you jsut gata help me man! please.

    if you can help ill like psot it all over enternet and thousands of people will be very happy.

    my email is:
    [Email Address Removed]

    Reply
  12. hi leo
    i keep getting, applet encountered a programming error.
    i clear the cache and relaunch firefox, then it tell me you may have a caching proxy between you and our web server how do i check the proxy setting for my browser?

    Reply
  13. are there any free mac applications that unblock proxys, like the ones used to block msn on school wifi or something like that?

    Reply
  14. @Gina
    I assume you’re talking about web proxies as proxy servers internal to a network should be able to be trusted. A web proxy server wouldn’t be any more harmful to your OS than any other web site you visit. There may be some rogue ones that try to infect your computer with malware, but they are not dangerous in and of themselves.

    Reply

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