Allow crawlers to scrape and index forum but only allow access via login?

Is it possible to allow crawlers to scrape and index forum but only allow access via login?

In other words, we would like the content to be indexed and found in searches, but the only way you can get to it is if you have a username/password.

is this doable? i apologize if this is posted in the wrong place, wasn’t sure where to put it.

No. Google won’t allow this; it is a violation of their terms.