If you have Koha and VuFind installed on separate systems, you can use the MySQL GRANT command to allow VuFind to read the Koha database. More details here:
So, for example, assuming Koha is on server1 (with a database named koha) and VuFind is on server2, you could do something like this:
1.) Log into Koha database as an administrator.
2.) Run SQL: GRANT SELECT ON koha.* TO ‘vufind’@’server2’ IDENTIFIED BY ‘vufind_password’;
3.) Edit web/conf/Koha.ini on your VuFind server and fill in the [Catalog] section appropriately. Using this example, host would be ‘server1’, username would be ‘vufind’ and password would be ‘vufind_password’
(Obviously, this is just an example – you’ll have to figure out server names and database names based on your current configuration, and you can pick any username/password you like for restricting the access).
Does that help?