Hi, I have just activated my first sw probe, on a dedicated CentOS7 VM, id 1000408. Out of habit, I did configure CentOS the way I usually configure my servers, notably by running OpenSSH on a non-default port and by activating only the ed25519 host key in sshd_config. I noticed 3 issues after having let the atlas-probe service run for a while, which included a couple of service restarts : 1. The SOS History table for the probe on the probe web page was not being populated with any data after the restarts. 2. The ./status/ssh_err.txt file showed the following message: « RSA host key for IP address '178.63.8.31' not in list of known hosts. » 3. I tried to set up a test one-off measurement using my sw probe by manually selecting its ID on the measurement setup screen, but it would not register the probe. I also noted after 12+ hours that no UDM was active for the probe from other users (from my experience with a hardware probe I have been operating for a while, it should be put at use by the network pretty quickly unless I am too impatient here ;-) ). My first action was to revert OpenSSH to default settings (use port 22, activate the RSA host key). This apparently contributed to solving problem 1 as the SOS History data started to appear on subsequent service restarts. Concerning the SSH error logged for the probe, the RSA Key for 'ctr-fsn01.atlas.ripe.net' was present in /var/atlas-probe/.ssh/known_hosts, but there was no entry in the file for a key for the corresponding IP address 178.63.8.31. I tried to add it to the probe known_hosts file but it disappeared after restarting the service. I guess the file is overwritten on service restart. I then added an entry for the RSA key for the IP address in the global /etc/ssh/ssh_known_hosts. The SSH error disappeared from the probe log file on the following service restart. So problem 2 solved for me, but that raises the question of whether there is a key missing for the probe known_hosts file for that IP address ? Now I am left with problem 3 and I have no clue as to why I can’t create a UDM which uses my sw probe ID. The built-in measurements seem to work fine if I read the probe web page info correctly. Any help welcome. Thierry