EJBCA to SignServer Peering uses port 443 (SSL/TLS) for communication. This connection is initiated from the EJBCA server to the SignServer node and needs to only go one way but allow return communication.
Create a security group that allows for TLS traffic within the VPCs. In this example, the VPC internal address space is 172.16.0.0/16 in US-East-1. Create a Security Group called Allow All TLS Traffic with the following rules:
This will allow any connections outbound to any address and any inbound connection on port 443 from any address on the 172.16.0.0/16 subnet. The same rule in the other VPC will also need the same rule configured. These rules may be tightened as required for the organization.
Apply these Security Groups to the EJBCA Cloud and SignServer Cloud Nodes in each of the VPCs. Right-click the node, select Networking and then Change Security Groups:
Apply the security group to the instances so that they can communicate with each other:
In the node details there is a link to View Inbound Rules. The associated IPs should be set up according to the following example (modified for your IP ranges subnets):
