Failed to connect to the source server by SSH: Incompatible ssh server (no acceptable macs)

Refers to:

  • Plesk 12.5 for Linux
  • Plesk Onyx for Linux

Created:

2016-11-16 13:11:45 UTC

Modified:

2017-02-05 16:40:41 UTC

1

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Failed to connect to the source server by SSH: Incompatible ssh server (no acceptable macs)

Symptoms

  1. Migration fails with error:

    [INFO] START: Check connections
    [ERROR] Failed to perform action: Check connections
    Error while checking connection settings: 'Failed to connect to the source server by SSH: Incompatible ssh server (no acceptable macs)'
    Migration was stopped.
  2. Source server is connected through Paramiko implementation of SSH2

  3. SSH is configured without Paramiko preferred MACs on source server:

    # grep MAC /etc/ssh/sshd_config
    MACs hmac-sha2-512,hmac-sha2-256,hmac-ripemd160

Cause

Such behavior is known as software issue with id #PMT-2360 and will be fixed in further product updates.

Workaround:

Paramiko prefers following MACs : hmac-sha1 , hmac-md5 , hmac-sha1-96 , hmac-md5-96 .

  1. Add string of MACs above to /etc/ssh/sshd_config , for example:

    # vi /etc/ssh/sshd_config
    MACs hmac-sha1,hmac-md5,hmac-sha1-96,hmac-md5-96
  2. Restart SSH server:

    # service sshd restart
  3. Start migration again.

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