Need to proxy or redirect a specific web address (but not others) so that all clients seem to originate from the same IP address

Posted on 2011-02-18
Last Modified: 2012-05-11
Hi, my company subscribes to a web site that limits access by IP address and we have clients located around the US that need to access it. These users are not on a common network, rather on home or SOHO connections.

I would like to set up a proxy, redirector, or other that I can point my users to so that they can access this one specific site from the "proxy" (thus the same IP address) and not use the proxy / redirector for the rest of their browsing...nor use it for any applications that require Internet Access.

It seems in IE (and other browsers) that if you set the proxy, all web browsing must go thru the assigned server (not what we want).

Would a so-called "anonymous redirector" accomplish this - where we format the web URL in such a way that the redirector points to the final web address and uses the redirector's internal IP as the originating address?

Any thoughts or suggestions?
Question by:kc10boom
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Expert Comment

ID: 34926589
Caveat:  Check the EULA of the web site you are using to see if what you want to do is permitted.

You need to look into using proxy.pac or wpad.dat files which are the files used to "automatically configure" the proxy settings for the browsers.  You can set up the file to go DIRECT for everything except this website and to use the proxy for the website.  You will probably still leave "tracks" that you are using a proxy so you still need to check the EULA of the web site.  

The .pac file will be similar to:

function FindProxyForURL(url, host)
    if (dnsDomainIs(host, "website_to_use_proxy"))
              return "PROXY <ip_or_fqdn_of_proxy>:<port_number_of_proxy>";
    return “DIRECT”;

For more see these sites or "Google" for proxy.pac or wpad.dat.

Author Comment

ID: 34928960
Hi, I'll research the links you sent over.... for the EULA, that isn't a problem.... it is just that the site restricts access via IP address and we would have so many differnent addresses (most running Dynamic addressing) that it would be overly difficult to manage....we need to use a single IP to connect to the web server.....

Would your solution work for Safari, IE, Firefox, etc? Our users have several browsers to select from....


Author Comment

ID: 34929052
Hi McCracky,

so your example says:

function FindProxyForURL(url, host)
    if (dnsDomainIs(host, "website_to_use_proxy")) -This would be the one site to use the proxy for?
              return "PROXY <ip_or_fqdn_of_proxy>:<port_number_of_proxy>"; - our Proxy web address and port?
    return “DIRECT”; - everything other than the one site goes direct??

I didn't see in the documentation where to place this PAC file or how to call it.... also, I assume it would work with both MS and MAC and all flavors or browser?

Thanks in advance for your additional comments.....
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LVL 12

Expert Comment

ID: 34930868
Your comments are correct above.  

It depends how you want to roll it out to get it to work.  It should work for any browser.

You usually put the proxy.pac file on a webserver somewhere.  MS redifined things for wpad.dat and wants it at the address:

For firefox, for example, in the proxy settings you have two choices:
- Automatic proxy configuration URL
- Auto-detect proxy settings for this network.

The first you put in the direct link to the file (e.g. http://domain.tld/proxy.pac)

The second takes the MS definitions and looks for the "wpad.dat" file at the root of the webserver of the domain of the machine.  If DHCP tells the machine it is part of, then the browsers should look for a link like to find it.  I usually made a proxy.pac file and a link to wpad.dat at the root of the webserver.

Author Comment

ID: 34965324
Hi, sorry about the delay....I've been traveling the last few days....

It seems from your comments above, that this file would need to reside on a web site that all my users would go to. Right now, they are spread out with different Internet providers and do not go thru the same network so this might be difficult.....

Question, would it make sense to create a www site (such as that my users could go to via a browser.... then have that server redirect the traffic to this specific web address? Otherwise, I'm not quite sure how I could implement the suggestion you have above.... of course, I could be dense and am missing the obvious......

I'm hoping to avoid having my users utilize a central proxy for most of their browsing because I fear doing so will slow down their current web access speeds. Perhaps I'm worrying needlessly....
LVL 12

Accepted Solution

mccracky earned 500 total points
ID: 34965787
Well, yes (and no).

You need a simple web server at a specific address if you want to use "auto-detect proxy settings for this network" to work.  Let's try an example:

Assume someone has a computer that gets it's address through DHCP and the DHCP server tells it that it is part of the domain "".  According to the wpad spec, that browser set to auto-detect would look for the wpad.dat file in this order:
4. failing to find it at one of the places above, it will fall back to not using a proxy.

There is another specification to send out the automatic proxy configuration through DHCP, but it seems at the moment to not work in either Chrome or Firefox (don't know why they missed that one!)

So, to implement the above you need to set up a webserver at the appropriate address to serve the proxy file to the browser (all this is automatically done by the browser, the user doesn't need to surf to any specific place to pick up proxy settings.)

The other option is to set up one location at any arbitrary URL and put it manually in the proxy configuration URL of the browser.  

This page would be good reading for you:
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Expert Comment

by:James Murrell
ID: 36434055
This question has been classified as abandoned and is closed as part of the Cleanup Program. See the recommendation for more details.

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