How can I allow an IP in webmin so I could connect to MySQL with specific user? I could do it in cPanel by adding that IP but in Virtualmin I think it's related to Host permissions or User Permissions.
You can certainly do this in Virtualmin, although access is generally configured on a per-domain basis.
To set it up for existing domains, do the following :
If you want all new domains to get acesss from 192.168.0.% by default, go to System Settings -> Server Templates -> Default Settings -> MySQL Database, and fill in the 'Allowed MySQL client hosts' field with 192.168.0.%
I admit that this is a fairly complex process, which is why I plan to add a more user-friendly single-page form for managing MySQL remote hosts to in the next Virtualmin release.
I enabled this feature in virtualmin owner limits:
and works fine.