"invalid protocol" while setting up connection parameters

Products

• Management Center - VA

Issue/Introduction

• "Invalid Protocol" seen over the connection parameters on Symantec Management Center while setup a connection and trying to connect/reconnect
• Issue happen for more than one device from Symantec Management Center
• There was no upgrade involved of Symantec Management Center or connected devices
• SSH Context Override was setup OK
• No specific logs in Symantec Management Center diagnostic logs
• Removing device from Symantec Management Center and adding back again did not help
• Regenerating SSH keys - (config)# device-communication ssh regenerate-key did not help
• Restarting Symantec Management Center services did not help
• Packet capture showed correct 3-TCP Way Handshake with successful Client/Server Key Exchange including sending some of the Encrypted packet (Client/Server)
  where you could see a RST from Symantec Management Center

Cause

Symantec Management Center - error - "Invalid Protocol"

Packet capture flow with the RST

Resolution

Management center has been hosted on Vmware NSX servers and there was a firewall rules blocking SSH connection.