Nofollow METATAG

There are 2 methods for what you want :

1. I suggest that you use a robots.txt file in your uie forum root:
   

   User agent : * 
   Disalow: /
   

   (If you want this for all spiders and for the entire site)

   Or you can specify per spider settings and per directory or file name in your drupal root:
   eg:

   User-agent: *
   Disallow: file.html
   

   User-agent: *
   Disallow: /forum/
   

   User-agent: googlebot
   or
   User-agent: WebCrawler

   and finally our list could look this way ( general example - adapt it to what your drupal site needs):

   User-agent: *
   Disallow:
   Disallow: /cgi-bin/
   Disallow: /images/
   Disallow: /forum/
   User-agent: Googlebot
   Disallow:
   User-agent: Googlebot-Image
   Disallow: /
   User-agent: MSNBot
   Disallow:
   User-agent: Teoma
   Disallow: /
   User-agent: Gigabot
   Disallow: /
   User-agent: Scrubby
   Disallow: /
   User-agent: Robozilla
   Disallow:
   

   PS: If your Drupal setup has aliases for all nodes (mostly happens when you use path and pathauto both) then add Disallow: /node/ to your robots.txt. Nodes with aliases are accessible from 2 URIs: the default URI and the aliased URI. Search engine bots will discover both over a period of time and this might lead to penalisation for duplicate content as well as twice as much crawling as is really required.

2. have you tried the module meta tags, also known as nodewords (http://drupal.org/project/nodewords) ?

   With this module you can setup, among other things, Default robots meta tag: :

   The ROBOTS meta tag offers a simple mechanism to indicate to web robots and crawlers wether the page should be indexed (INDEX or NOINDEX) and whether links on the page should be followed (FOLLOW or NOFOLLOW). Here you can enter the default robots meta tag to use for all pages. If unsure, select "ALL=INDEX,FOLLOW".

   and

   Select the meta tags you want to be able to edit on the edit page of nodes, terms and vocabularies.

Did this solution work?

I like nodewords since it lets you choose the description metatag, but it forces to choose between some combinations of indexing and following for the whole site, which seems to be a problem when you want to selectively add nofollow tags. Does anybody know a good approach to this issue?