PICSRules

The PICSRule Project is being spearheaded by Ian H and is in development in the GRC Opt-Out newsgroup. For now, I'm only providing a repository for the files. I can't answer any technical questions about the files or their use. Please post questions to the GRC opt-out newsgroup or email me and I will forward your email to Ian.

The following is taken from a post by Ian H:

Subject: PICSRule file to block Doubleclick
Date: Fri, 4 Aug 2000 10:05:20 +1200
Newsgroups: optout

Content advisor CAN be used to block ad sites. However the popup problem remains. But the advantages of doing this are so great that I think it is worth persisting with it and trying to find a cure for the popup problem.

Check out the [doubleclick] file. The syntax is fairly self-explanatory. A PICSRule file MUST contain a name (I found that out the hard way). Note that !23 after an IP address sets a subnet mask to block all IP addresses that share the same initial 23 bits. The rest of it is pretty obvious.

Note that it blocks doubleclick in two ways - firstly by using wildcard matching on the URL itself which the hosts file cannot do, and secondly by blocking various IP ranges which the hosts file cannot do either.

The patterns were derived from looking at the doubleclick entries in the hosts file which we have all been using. In researching the IP ranges I was rather conservative, only blocking an IP block when I could definitely identify that all sites within it belonged to doubleclick. When I was uncertain I blocked only the single address.

In the course of looking for the IP addresses to block I discovered that about a third of the entries in the hosts file no longer exist. Doubleclick seems to rotate server names very rapidly. It has its own DNS servers relay1 and relay2 to which mail for the retired servers is redirected. I suspect it has some kind of automatic mechanism for advising web site owners to update their URL's when the server names change.

I invite those interested to test this system and help work the bugs out of it. To make this workable we need:

1. A solution to the popup problem.

2. *.prf files to block other offenders.

^ Top

PRF Files  

DIRECTIONS: Any simple editor (eg: Notepad) can be used. Copy the *.prf files and save each to a separate file with extension .prf. You can then import the files into content advisor and have a play with them.

^ Top