Is there any setting in phpBB or mod that stops people that have not register to see the full content?
Yes this is pretty easy to do,go to your Administration Control Panel,under Users and Groups you will see Groups’ forum permissions,there select Guests and click Go,then select all forums and Submit and for Role select No access.
Thats it,hope it helps
If you mean search engines,I dont think so,but if you want to be sure,you can always block search engines,but if you are referring to phpbb's search feature,no
To be honest I don't really understand what you mean,maybe Google indexed those forums,and Google is able to see the text,but for users to be able to see it,they need to register...
Could you further explain what you want phpbb to do ?
as per the permissions
bot permissions - this will set up the permissions for SE bots and spiders and if they can see the content of your forum then it will be indexed in search engine
guest permissions - they usually come from a search engine and there permissions can be setup separately so you can choose individually for each sections and forum that whether they can see the posts or not.
a simple tip for those who want to keep non subscribers from viewing and letting google index.
if google has an index of page then literally everyone in this world has access to it what to know how.
find a page which is for members only on google and click on the small cached link and voila there is your entire page in full glory staring back at you.
just wanted to add my two cents that there is no point in hidding stuff room people if yoou don't want to hide it from google also.
another advance trick which many uses is to change your useragent to googlebot effectively letting everyone think that its google who is viewing my website.