I recently pressed a G7 MicroServer back into service, and disccovered that I couldn’t connect to it over SSH. This seemed odd given that I am quite certain I remember doing so before. A quick nmap scan showed that the ssh port was definitely open on the ILO:

Starting Nmap 6.40 ( http://nmap.org ) at 2020-06-07 23:06 BST
Nmap scan report for 192.168.0.2
Host is up (0.0086s latency).
Not shown: 992 closed ports
PORT STATE SERVICE
22/tcp open ssh
80/tcp open http
111/tcp open rpcbind
427/tcp open svrloc
443/tcp open https
2068/tcp open advocentkvm
5988/tcp open wbem-http
5989/tcp open wbem-https

Increasing verbosity on ssh connection (ssh -v), yielded some interesting insight, specifically:

debug1: match: OpenSSH_5.2 pat OpenSSH_5* compat 0x0c000000

So it could in fact be that more modern ssh tries to connect with ciphers and protocol options that the now relatively ancient OpenSSH 5.2 doesn’t quite understand. So I quickly grabbed OpenSSH 5.2 portable, built it and tried with that, and – success! Doing it again with verbosity turned up showed what ciphers and MACs were used. I added the following to my ~/.ssh/config:

Host 192.168.0.2
    Ciphers aes128-ctr
    MACs hmac-md5

And lo and behold, ssh-ing to the ILO from recent ssh on EL8 now works!

Hopefully this will save somebody some time in the future, or prevent them from throwing away what is still a perfectly usable microserver.