Create a password file with a hard to guess name like ~/.htpass87s9adf with usernames and passwords using the commands

htpasswd -B USERNAME PASSWORD PASSWORDFILE
chmod o+r PASSWORDFILE

Create a file .htaccess using and adapting the following content. In the lines Allow from you can add IP addresses which will have access without password authentication.

Options -Indexes

AuthName "Authorisation required"
AuthUserFile /home/user/PASSWORDFILE
AuthGroupFile /dev/null
AuthType Basic
require valid-user

Order deny,allow
Deny from all

Allow from x.y.z.w
Allow from .......

Satisfy Any

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