Can't add SMP server to the internet gateway Error: the underlying connection was closed: An unexpected error occurred on a send

Products

• IT Management Suite
• Client Management Suite

Issue/Introduction

When trying to add the SMP server to a new CEM gateway it would fail with an error:

The underlying connection was closed: An unexpected error occurred on a send.

Environment

ITMS 8.x

Cause

A firewall rule was blocking the traffic

Resolution

The firewall rule was modified to allow the traffic to the SMP server.  

In this case Wireshark showed three hops between the gateway and the SMP.  The TLS handshake started and when the client hello was sent it was immediately followed by a RST.  The time to live dropped by 1.  This indicated that a device in the middle was sending the reset.   After they reconfigured the firewall rule the problem was resolved.