Server joined to AWS Managed Directory Services need outbound port 445?

This address space is used by AWS for many services and they mention it in several documents.

Pretty sure it’s related as that addresses space is reserved and IP addresses are not being issued on the internet. Similar to RFC1918. These are bogon address space.

If you google aws 198.19 you will get many hits regarding this reserved space they use.

https://docs.aws.amazon.com/workspaces/latest/adminguide/workspaces-port-requirements.html

https://docs.aws.amazon.com/vpc/latest/userguide/vpc-cidr-blocks.html

https://docs.aws.amazon.com/fsx/latest/WindowsGuide/self-manage-prereqs.html

Yes, those IPs belong to AWS Managed Directory Services. From this document:

https://docs.aws.amazon.com/directoryservice/latest/admin-guide/ms_ad_getting_started_prereqs.html

AWS Directory Service uses a two VPC structure. The EC2 instances which make up your directory run outside of your AWS account, and are managed by AWS. They have two network adapters, ETH0 and ETH1. ETH0 is the management adapter, and exists outside of your account. ETH1 is created within your account.

The management IP range of your directory's ETH0 network is 198.18.0.0/15.