Pull/Test credential would fail for Cisco devices

Products

• VMware Smart Assurance
• Network Observability

Issue/Introduction

Pull/Test credential would fail for Cisco devices i.e for Cisco 17.x version and above as 'ip ssh bulk-mode' is enabled.

Below error is seen:

commmgr.log:

Server sent disconnect message type 2(protocol error): "Corrupted ETM-MAC on input

Device log:

%SSH-3-BAD_PACK_LEN: Bad packet length 770621782

Environment

NCM - 10.1.x/24.3.x

Cause

ip ssh bulk-mode is supported from putty version 0.69 however NCM 10.1.13 has putty version 0.68 hence device is rejecting NCM connection. 

Resolution

NCM 24.3.10 has higher putty version ie version 0.81, recommendation is to upgrade NCM so that command 'ip ssh bulk-mode' would be supported. 

As a workaround, disable 'ip ssh bulk mode' at device end and try pull job in NCM for problematic device, it should work. 

 

Additional Information

This putty release in NCM 24.3.10 support OpenSSH 9.x version.

Reference : What's New in 24.3.10