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rel=nofollow attribute to links

Google proposes an interesting scheme to defeat blog/wiki spam that is gaining adoption:

From now on, when Google sees the attribute (rel="nofollow") on hyperlinks, those links won't get any credit when we rank websites in our search results


So, we should implement it. The question is how to add this to some class of users (visitors) and not some others? (regular users). Do we enforec it only in the Comment Plugin, or at each save?

-- ColasNahaboo - 19 Jan 2005

Assuming we would add 'nofollow' to the external links in comments submitted by comment plugin, or by TWikiGuest, this sounds like a good idea. To make this easier to configure, maybe we need a $publicMode setting in TWiki.cfg so that email address spam munging and comment spam features are auto-enabled? Somewhat like $useLocale, without which the I18N settings are ignored.

I'd also like to see a comment blocking approach since it's possible that the comment spammers will not know or care that TWiki has a Google search rank limiting feature such as this - they will probably just spam all Wikis and blogs regardless, although Google seem to have got key bloggers to sign on which may mean it becomes a de facto standard.

-- RichardDonkin - 20 Jan 2005

An approach could be to remove most html tags on saves, and add the nofollow, via a per-web setting. This would promote having on public sites articles in one web, writable only by trusted users, and %INCLUDE-int comment topics from a public web with this safety setting. Do somebody see a drawback to this scheme (on saving in "unsafe" webs, the conversion would be disabled for TWiki Admins)

-- ColasNahaboo - 20 Jan 2005

Why not, after all other processing, check every external link in rendered html against a list that maps domains to follow/nofollow and add the rel="nofollow" attribute accordingly. If the domain isn't on the list add it as nofollow, and then TWiki admins could periodically check the list for new additions and change any they recognise as safe to follow.

It could also be used to monitor if spam is being added and bad domains could be tracked down and removed. You could even allow admins to mark domains in the list as nosave so that from then on save operations will fail if they contain the domain.

-- SamHasler - 21 Jan 2005

Interesting idea but the domain list sounds like a lot of maintenance for the admin - would be better if we could find a Perl module used by blogs that has regularly updated list of URLs used in WikiSpam, and then just build some code around that.

-- RichardDonkin - 21 Jan 2005

Ward pointed me to a related way of fighting WikiSpam: http://c2.com/cgi/wiki?WikiWikiSystemNotice. The idea is to tell the search engine not to index recently updated topics. The time is set such that people monitoring the contributions can remove spam before search engines pick it up.

How about combining those two ideas? Here is how: TWiki adds a rel="nofollow" to all external links if the topic has been updated recently. That can be made configurable in TWiki.cfg, e.g. $noFollowTime set to the number of hours the nofollow is added to external links, or set to 0 to disable.

On the other hand, should that go into the core code? Arguably not since the target users use TWiki behind firewall. This could be done in a Plugin at the end of the rendering, e.g. by the endRenderingHandler. Since it is related to the BlackListPlugin it could be added there, configurable with a NOFOLLOW_TIME Plugin setting.

-- PeterThoeny - 21 Jan 2005

http://google-blog.dirson.com/rel-nofollow.php lists tools supporting the nofollow attribute.

-- PeterThoeny - 21 Jan 2005

The BlackListPlugin supports now the rel="nofollow" parameter. The latest Plugin version is installed on TWiki.org. Any topic that is one day old will have the "nofollow" parameter added to external URLs. Look at the HTML source of a recently edited topic / older topic to see.

-- PeterThoeny - 22 Jan 2005

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Topic revision: r9 - 2005-01-25 - SamHasler
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