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What is " a PROXY SERVER? "

Posted on 2008-10-04
Medium Priority
Last Modified: 2013-11-13

1. This is related to a "PROXY SERVER"
2. My questions: (Please FIRSTLY explain it with your own WORDINGS, and then provide the "Links"), i) Is a proxy server a PART of DHCP Server? (That provides the IP address to the client), ii) Or is it PART of the DNS Server? (That do the Name Resolution), iii) What is this "Proxy Server?" (The Function, The Purpose, etc), iv) What is the difference between This Proxy Server and a DHCP Relay Agent?, v) How to configure this "Proxy Server?"
3. Thank you

Question by:tjie
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LVL 13

Assisted Solution

leegclystvale earned 600 total points
ID: 22641967
A proxy server is something that is between you and where you want to get. ie, the internet. It is a server that can have rules when you type an address, it can refuse your request for the internet, it can allow your request depending on what it is. A proxy server usually has ISA installed and by this you can have rules to allow or disallow or redirect requests from users wanting a certain address on the internet.
In your internet connections settings, you specify a proxy server so that any requests for the internet go through that server first and any rules you setup will apply before they get to the big bad internet.
Hope that helps
LVL 13

Assisted Solution

leegclystvale earned 600 total points
ID: 22641977
A DHCP server just gives computers IP addresses, subnet mask and default gateway usually. A relay will just serve as a proxy for a dedicated DHCP server for exqmple it will pass the info from one DHCP server to another DHCP server that's acting as a relay to the clients.
This usually happens when the clients are ina  different location and still need to use the DHCP server in another location across a router.
LVL 13

Expert Comment

ID: 22641984
What do you want a proxy server for? You need to specify what you want to do and then solutions to your request will follow. If we don't know what you want to do, we can't give you an answer.
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Accepted Solution

placebo69a earned 800 total points
ID: 22642026
Let me try and put this as simply as possible:
A proxy server is a server other computers use to access the internet. This is good because that way all the internet communication on a network is going out of a single machine, instead of each computer having to get there on its own which clutters the network.
Proxy servers also have cache (memory) so that if a computer using the proxy makes the same request as another computer using the proxy it doesn't have to go search the internet to answer the request, saving time and bandwidth.
Proxy servers are also good for bypassing firewalls. Most firewalls block all ports except a few and sometimes you need to go around the firewall to access a certain port. For instance if you want to play a MUD you need to be able to use the telnet port (23). But if your firewall is blocking the telnet port you can use a proxy instead and it will use the telnet port for you, while your computer talks to it on a more standard port (with better chances of not being blocked by a firewall) such as 80, 8080, or 3128.
Proxy servers are not a part of DHCP or DNS servers.
You can configure a proxy server in two simple ways:
  1. Download proxy server software and install it on the computer you want to use as a proxy server.
  2. Access your router using a web browser and set up a proxy server using the router options - This only works if your router has this option
You can find links to free proxy server software here.
Let me know if this helped. :)

Author Comment

ID: 22642297
Hi Placebo69a,

1. Per your explanation, it seems that the Proxy server is a third party software, right ?

2.  Does  Windows 2003 server have the capability to be a proxy server? (I mean without installing the 3rd party software)

3. Thank you

LVL 70

Assisted Solution

KCTS earned 600 total points
ID: 22642370
There are many types of Proxy Server, the commonest being an internet proxy.
The way in which this works is that the client computer contacts the proxy server, then the proxy server requests pages from the internet on the clients behalf, then returns them to the client. This provides a number of advantages - the proxy server for example can be set up to block access to certian sites for certian clients, it can also cache pages so that pages requessted by one client can be cached on the server and can be delived directlt to subsequent clients.

Windows 2003 does not have a proxy server built in - but Microsoft ISA server  is a proxy server (and firewall), that can be installed on a 2003 server to give it these capabilities. Others are avaibale (eg SQUID)

You ask has a proxy server got anything to do with DHCP - well in short no, but there is something called a DHCP Relay agent (part of routing and remote access built into Server 2003), which does act like a DHCP proxy, intercepting DHCP requests from clients on one subnet and directiing the request to a DHCP server on another subnet. This is required whre DHCP broadcast packets are unable to travese subnets as the routers do not comply to RFC 1542 (or the function has been disabled)

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