Access method didn't change since you asked for 12.1.2. Credentials are dba and initial admin password.
You'll find the database schema for 12.1.5 here:
Symantec Endpoint Protection 12.1.5 database schema (see "Attachments")
https://support.symantec.com/en_US/article.DOC7660.html
Unfortunately, I don't know how Lankeeper works, so I'm not able to provide detailed tips.
HTH!