There are multiple ways to configure content access in Dev Portal, but the two main ways are to use either the Drupal Content Access module or the Taxonomy Access Control module.
We also have an article on how to use role based access control on SmartDocs documentation.
Content Access Module
The Content Access module allows you to configure permissions per content type or page by role or author. For example, since all blog content is one content type, you can easily control access to your blog by setting read access to a "blog readers" role, or create a "blog editors" role that can only edit and create blog entries in Dev Portal.
The problem is that Content Access works on content type, so it is hard to do something like lock down one forum since all forum posts are the same content type. You can configure the module to allow you to configure access control on each individual node, but that means if you wanted to lock down only part of your documentation (which is usually just a "Basic Node" content type), then you would need to go to each node (page) you want to restrict and configure the permissions.
Pros
Cons
Learn more at: http://community.apigee.com/articles/2121/content-access-control-on-developer-portal.html
Taxonomy Access Module
The Taxonomy Access Module works great for restricting access to nodes (pages) any way you want, but it takes more work. You will need to understand Drupal taxonomies and spend some time configuring the module.
However, if you need to lock down only part of a content type such as documentation or forums, this module will fit better than Content Access Module.
Pros
Cons
Learn more at: http://community.apigee.com/content/kbentry/2383/content-access-control-on-developer-portal-using-t....