The first RSP connection shown in the rsp.log consistently fails on RHEL 6 remote systems

Products

• DX Unified Infrastructure Management (Nimsoft / UIM)

Issue/Introduction

We’re monitoring RHEL 6 systems using RSP 5.58+ and have noticed that the first connection recorded in the rsp.log always fails, but the second attempt with ssh1 works fine.

Note that the RSP probe does not trigger an alarm.

Why does the first connection consistently fail?

Here’s the rsp.log entry.

rsp: Connection failed for host <remoteserverexample>: kex error : no match for method server host key algo: server [ssh-rsa,ssh-dss], client [ssh-ed25519,ecdsa-sha2-nistp521,ecdsa-sha2-nistp384,ecdsa-sha2-nistp256,[email protected],[email protected],rsa-sha2-512,rsa-sha2-256]
rsp: Retry connecting with ssh1
rsp: connect_ssh:  user <username>
rsp: connect_ssh: host <remoteserverexample>
rsp: connect_ssh: timeout 30
rsp: connect_ssh: pass_less_ssh 1
rsp: connect_ssh: do ssh_connect for host <remoteserverexample>
rsp: Authentication success for host <remoteserverexample>

Environment

rsp 5.58+ and RHEL 6 remote systems

Resolution

When monitoring RHEL 6 systems, the first connection attempt by the RSP fails because the probe uses SSH2 for authentication, which isn’t supported by RHEL 6.