Bust Banner Ads with Proxy Auto Configuration
This is a simple change to the configuration of your web browser,
setting it such that it avoids making connections to
banner advertisement servers and avoids downloading ad images.
If your browser can't connect to the advertisement server,
it can't show you the ad image.
The trick behind this is that it uses a mechanism
already built into most recent browsers
(Chrome, IE, Firefox, Netscape, Mozilla, and Opera)
and available on most platforms (Windows, Mac, UNIX).
Simply download and save no-ads.zip.
Extract the no-ads.pac file from the ZIP archive.
It is a plain text file. Open it with an editor or text viewer,
and read the instructions it contains.
(hint: to open the file on Windows, right-click it and select
Open With, and choose wordpad - do not use notepad)
I've created a
where people can discuss no-ads.pac and proxy auto configuration.
(this replaces the network54 forum, which remains as an archive)
for every URL it was about to load.
The purpose of this mechanism is to automatically and dynamically determine
an appropriate HTTP proxy,
where such a proxy might be dependent upon the URL involved.
Mozilla has the
My use of Proxy Auto Configuration is to avoid using a proxy.
URLs of known anoying images are sent off to a
black-hole proxy server
which swallows the request (and prevents the image from being loaded).
URLs of actual content are unaffected, and directly handled by the broswer.
(For what it's worth, I came up with this concept back in 1996 when I was looking at
In general, it works with all browsers these days, since they all implement
Proxy Auto-Config files.
Please post updates and corrections to
the web forum.
Adding URLs to block is easy. It will be obvious once you look at no-ads.pac.
The industrious can even find
a search engine
and directly add those URLs to the blocked list
(if you do, announce your work
in the web forum).
Yes! (See the directions inside the no-ads.pac file)
This was working in Chrome 50. (I've not checked since then).
- IMPORTANT! (2017)
Similar to Firefox 51, newer Chrome strips the path from the url parameter being passed to the PAC script (in the name of security).
You need to enabel this special preference for no-ads to work:
PacHttpsUrlStrippingEnabled to false.
(untested by me)
- Mozilla, Firefox
It works perfectly with all versions of Mozilla from 1.0 and up,
and with Firefox 1.0 and up.
- IMPORTANT! (2017)
As of Firefox 51, it strips the path from the url parameter being passed to the PAC script (in the name of security).
That breaks the basic mechanism that no-ads depends upon.
See this message in the forum for more details.
It should work if you set the preference (under about:config)
network.proxy.autoconfig_url.include_path to true
Alert! this setting is broken in FF51, but fixed in FF52 (released March 2017).
Mozilla older than 1.4 (and Netscape older than 7)
require a black hole proxy.
Newer versions of those browsers (and Firexox) implement
Proxy auto-config failover,
which allows them to utilize no-ads.pac without a black hole proxy.
- Netscape Navigator
It works with recent Mozilla-based Netscape browsers (6.x and 7.x)
(I've not tested it, but I have many reports of success).
It works with all versions of Netscape Navigator from 2.0
(when I started using this trick)
up to and including 4.0x and 4.7x
(but you should not be using those old browsers anymore).
This will not work on versions of Navigator prior to 4.0
(and may not work on pre-6.x versions of Netscape).
For those old browsers,
use the last version of no-ads without RegExps.
- Internet Explorer
Microsoft added Proxy Auto Config to Internet Explorer
(their documentation on this used to be at
but Microsoft has removed it).
I have tested with IE versions 4, 5, 5.5, and 6.
I've stopped testing with IE as of IE8.
With IE5 and later, you can load the PAC file from a file: URL
This form works: file://c:/no-ads.pac.
For all versions of IE, you must correct the security settings.
Under Tools->Internet Options, select the Security tab.
Select Local intranet and then click the Sites box.
Then, remove the check mark next to the
include all sites that bypass the proxy server option.
For IE5.5 and later,
you must disable the Auto Proxy Caching mechanism,
as it defeats the ability to to block ad images on servers that also serve
To prevent this, add the registry key described in MS KB article
To make it easy, you can just download and click on this registry file:
Details: This sets the EnableAutoProxyResultCache registry key for the current user.
It also (thanks to InvisiBill)
adds a new group and checkbox to the IE's Internet Options
Advanced tab, that allow you to easily change the setting in the future.
You must run it once for each user
on your system using no-ads, as this is a per-user setting
(the same key doesn't work under HKLM).
- Microsoft Edge
- Other browsers
(like Gecko and Webkit-based browsers),
then this should work.
If you try a browser not listed here, please
post an update on the web forum.
It will also work if you already need to use a Proxy Auto Config file,
although that's a little tricky to setup at this time.
See this thread in the old forum.
If you use a ad-removing proxy
then (by definition), all of your content
must go through the proxy filter.
This might slow down the loading of pages,
or cause other problems as the proxy is always running.
The Proxy Auto Config mechanism avoids this by avoiding a
proxy altogether for the content you actually care about.
Some people use an /etc/hosts (or on Windows, hosts.txt)
file to map hostnames of ad image servers to a non-responding address.
The downside to this is that it cannot be used
for a server that serves both ad and non-ad content.
no-ads can block such hosts easily, but it can also just as
easily block some content on those hosts, not all of it,
since no-ads can block based upon the URL, not just the hostname.
Try this test page.
If you can see the picture of me, then no-ads isn't working.
If the picture is blocked, then no-ads is working..
You can also try these test URLs:
If your browser displays Yahoo's Sorry the page was not found,
then no-ads isn't working.
If you are having problems getting no-ads to work,
post a message in the web forum.
The simplest black-hole proxy is one that doesn't even exist.
If you use an address on your local host,
then the request will fail immediately.
This is how no-ads.pac is configured by default,
so if you don't mind seeing a missing image
icon for each image that has been blocked,
you have nothing to change or configure.
This works with Mozilla 1.4, Netscape 7.1, and all versions of IE.
For other browsers, you will need an actual black-hole proxy that somehow
denies every request given to it. It can either return a HTTP 501 error code,
or server up a replacement image for the blocked ad image.
Here are some options:
There isn't a provision to deactive no-ads for just one site.
However, you can deactivate no-ads for your current browser process.
(This was contributed by Sean Burke)
- My simple noproxy shell script
that acts as a blackhole proxy.
It is invoked (on UNIX) via inetd (or equivalent). It can be configured to
return an image,
a redirect to an image,
or an HTTP error code ("501 No Ads Accepted").
Sample images include a clear (blank) image, or a no-ads logo.
Stephen Ostermiller made this image for noproxy that makes it
obvious something was blocked,
and scales well: noproxy.blocked.gif
- Sean Burke has a black-hole script written in Perl (UNIX; can be made to work on Windows)
- Larry Wang has a black-hole program for Windows (and he also offers the source code)
Mozilla always uses one process for all windows/tabs.
IE uses one process per invocation: if you use open in a new window,
the new window is controlled by the same process; but if you click on IE
on the desktop, you get a new process.
Use these special links to deactivate or re-activate no-ads for the current browser process.
Hint: drag these links to your browser's Link or Personal toolbar.
Sorry, I will not be updating these versions:
No-ads is not a popup stopper. But, it does stop some popups
And on other popups, it doesn't stop the popup window from appearing,
but it stops your browser from loading the content.
Required for Netscape 2.x, 3.x, and possibly 4.x.
Possibly needed for IE4.x.
alert and var statements.
Required for IE3.
Personally, I use FireFox and I enable the
Block Unrequested Popup Windows option.
I mostly never see any popup advertisements.