What is this?

This knowledgebase contains questions and answers about PRTG Network Monitor and network monitoring in general.

Learn more

PRTG Network Monitor

Intuitive to Use. Easy to manage.
More than 500,000 users rely on Paessler PRTG every day. Find out how you can reduce cost, increase QoS and ease planning, as well.

Free Download

Top Tags


View all Tags

Intermittent login fails with host key algo mismatch in 0.2% of cases

Votes:

0

I get the following consistently, but rarely:

Oct 17 09:54:10 nonprod-view sshd[2856338]: Unable to negotiate with 80.XXX.XXX.XXX port 16849: no matching host key type found. Their offer: ssh-rsa [preauth]

A few seconds before or after, login succeeds. How do I investigate further? PRTG: 22.3.79.2108+, SSH: OpenSSH from current Ubuntu 22.04

host-key openssh ssh

Created on Oct 17, 2022 8:37:38 AM



1 Reply

Votes:

1

Hello Ralph,

I'd recommend to setup a WireShark capture on the probe host with a host 80.XXX.XXX.XXX capture (not display) filter.

This way you can wait for the failed authentication to compare a successful attempt with anon successful one.

no matching host key type found is pretty straight forward, I'm curious if the device rejects the attempts by not offering the appropriate host keys.

Kind regards,
Felix Saure, Tech Support Team

Created on Oct 18, 2022 5:45:35 AM by Felix Saure [Paessler Support]




Disclaimer: The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.