Under Options > Discusssion, Comment Moderation you can set comments to be moderated if they contain 1 or more links. Not quite a ban, but would keep such comments from appearing on your blog before removing them.
Thread Starter
shimmy
(@shimmy)
Is there a way to ban them all and not to let them in moderation at all
Best I can suggest is, on that same Options page, enter:
href
in the Comment Blacklist field. Any comment with that in the content (which would be needed for a proper <a> link) would be marked as spam. If you use a spam utility plugin like Akismet, that can then take care of them for you (in the sense of deleting them from the database).
Or add “http” to that block list.
I wouldn’t use ‘http’ as the blacklist feature hits the comment author url as well (and adding it would assure nearly all comments end up blacklisted).