TransmissionService webservice endpoint is exposed to internet - Security Issue

TransmissionService webservice endpoint is exposed to internet and the SOAP header credentials is more like a Basic Authentication with (Username/Password) - If the credentials are compromised, anyone could post the message could cause DDoS for the webservice.

/GC3Services/TransmissionService/call

Within organization any one can post the messages and we will not be able to control.

This is not as per the security policy , it requires IP based restriction.

We have similar setup with our On prem - with firewall restrictions on the inbound traffic.

I see a documentation for the cloud console  - we need some guidance how this can be implemented for OTM Cloud