Veeam Backup & Replication
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When attempting to add a managed Linux server, you may receive one of the errors below.
Failed to negotiate key exchange algorithm Client encryption algorithm not found Server HMAC algorithm not found
Review the configuration of your /etc/ssh/sshd_config file and verify that at least one of the Ciphers, KexAlgorithms, and MACs listed below are present. You do not need to add all of the examples below, just make sure at least one from each is present.
Supported Key Exchange algorithms:
See the man page for your sshd_config file and/or query for the supported ciphers, key exchange algorithms, and keyed-hash message authentication codes using the following command:
If needed, modify the sshd_config file to add one of the supported entries. Then, to generate the newly added keys, run
and restart the sshd service on the machine (reboot works fine, too).
Some systems offer an option in the GUI to disable or re-enable SSH logon, but these do not always actually restart the daemon. Typically, it is best to restart the service using the command
service sshd restart
or your distribution’s equivalent.