Prevent User Change Password - User Portal

Hi,

Is it possible to remove the option for a user to change their password from the user portal? Or at least enforce complexity? I can't trust my users to not set their password to "password"

I've searched for any info on customising the portal, can't find anything.

It would be nice to also remove other options also like smtp quarantine and internet usage - just have client download and clientless bookmarks.

Thanks for any help.