FusionAuth Cloud instances may or may not have static egress IP addresses; please open a support ticket with your instance name to learn more.

VPC peering is not currently supported, though that issue is the right one to follow for future developments.

You can also use an LDAP proxy to solve this issue.

FusionAuth -> LDAP proxy -> AD

where the LDAP proxy is in the DMZ and AD is configured to only talk to internal network values or the LDAP proxy.

Here's a StackOverflow post with more details.

FusionAuth has a bunch of import scripts, but one that you are probably most interested in is the CSV importer, which takes a CSV file and then calls the user import API.

Here's the link: https://github.com/FusionAuth/fusionauth-import-scripts/tree/main/csv

Of course, LDIF is not CSV.

Instead of using a CSV gem to get the list of users and their attributes, use a gem that can read LDIF. Here's a candidate. https://www.rubydoc.info/gems/ruby-ldap/0.9.19/LDAP%2FLDIF.parse_file but I'm not sure what the state of the art for ruby LDIF parsing is nowadays.

If you pursue this, please submit a PR to that repo because there may be other folks who want to import users from LDIF

An alternative would be to have them manipulate the LDIF file into CSV and import that using the csv importer. See https://www.google.com/search?client=firefox-b-1-d&q=ldif+to+csv for some examples on how to do the LDIF->CSV transformation.