I'm installing service on the cloud machine and I was wondering on port vulnerabilities for my customers.
My service which lives on server A (often on a customer site) needs to access server B (lives in a cloud) through port 1234. On server B there's a service running on port 1234, but customer often wants to block access to it as non standard port. Server A doesn't have a service running on that port, but still needs to be able to communicate on it.
Is there a vulnerability of opening port, which is used to establish connection with another service? If you scan a machine A, the port would be open, but there's nothing running on it.
Typical solution would be enabling port 1234 between IP A and IP B, but in cloud, we can't guarantee the IP addresses.