[Pmwiki-users] Preventing "comment spam"

[Patrick R. Michaud]

On Wed, Jan 19, 2005 at 11:12:28PM +1300, Robin wrote:
> On Wednesday 19 January 2005 21:25, Thomas -Balu- Walter wrote:
> > Thats the same problem with simply not linking unapproved URLs. The
> > reason why we do that is to avoid helping them improve their page
> > ranking.
> But it is really easy to see non-linked URL from a linked one, whereas a 
> rel="nofollow" one isn't obvious unless you look at the source.

True, but given that Google's announcement is getting a lot of play
on slashdot and other forums, spammers will undoubtedly know about it
soon.  This doesn't necessarily mean they'll stop spamming -- they may
have other motives for doing it besides Google page ranks, but it
substantially reduces the incentives for doing so.

> > The solution will be the quantitiy of Wikis implementing this. If all
> > PmWikis will have this enabled in the future they will quickly learn
> > that this trick does not work anymore.
> This might be true, too.

I think so.  In fact, I think that any wiki that doesn't implement 
rel="nofollow" will soon be the focus of spammers' efforts, which is
why PmWiki will need to enable it as the default for all links.

> >         - rel="nofollow" for all external links (default)
> >         - rel="nofollow" for unapproved external links
> >         - no rel="nofollow" at all
> >         - not linking unapproved external links at all
> Having these as options might well be a good thing, with the default as you 
> suggest (on all wikis), in order to discourage people from attacking PmWiki.

All of these options are presently available in PmWiki v2:

1. rel="nofollow" for all external links (new default for beta20)
      $UrlLinkFmt = 
        "<a class='urllink' href='\$LinkUrl' rel='nofollow'>\$LinkText</a>";

2. rel="nofollow" for unapproved external links only
      $UnapprovedLinkFmt =
        "<a class='apprlink' href='\$LinkUrl' rel='nofollow'>\$LinkText</a>";

3. no rel="nofollow" at all (default for beta19 and earlier)
      $UrlLinkFmt = 
        "<a class='urllink' href='\$LinkUrl'>\$LinkText</a>";

4. not linking unapproved external links at all
      $UnapprovedLinkFmt = "\$LinkText";

Personally, on pmwiki.org I'm going to do #2 -- i.e., rel="nofollow"
for unapproved external links only, because I want approved links
to gain the page rank benefit of having been listed on my site.  I'll
probably also add an icon or marker after the unapproved links that
lets them be quickly approved (via the appropriate password).

There's also a fifth category of links -- those that are generated
via the InterMap.  It's my feeling that InterMap links should not
receive the rel="nofollow", as those sites have already been approved
by the site maintainer.  But that will come in another release.

In PmWiki v1, one can add rel="nofollow" to external links via:

      $UrlLinkFmt = 
        "<a class='urllink' href='\$Url' rel='nofollow'>\$LinkText</a>";

I'll be doing this to the wiki-v1 site on pmwiki.org.

Pm