OpenQRM uses dropbear for the communication and exchange of messages between the server and the appliances. When something goes wrong in this communication OpenQRM can’t function correctly. It can’t access the applicances for status updates and commands. These communication problems are often caused by a misconfiguration in dropbear. The most seen problem is a misconfiguration in the the public and private dropbear key.

The keys should be synchronized between the server and the appliance. On the server grep the public key with the following command:

[root@localhost log]# /usr/lib/openqrm/bin/dropbearkey -t rsa -f /usr/lib/openqrm/etc/dropbear/dropbear_rsa_host_key -y
Public key portion is:
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAAAgwCBvwSO7vBBL2avDMds...pVn root@localhost.localdomain
Fingerprint: md5 65:ca:5b:3b:05:c3:61:6d:fb:75:2f:c0:d2:7e:02:cf

Copy the ssh-rsa public key in /root/.ssh/authorized_keys on the appliance.

Now communication should be established.

OpenQRM event log with example of error message caused by communication problem:

openqrm-cmd-queue ERROR executing command with token 64d478dcac6670e5fb000e7c4954863b : /usr/lib/openqrm/bin/dbclient



Aug 26 23:19:45 localhost httpd: openQRM resource-monitor: (update_info) Processing statistics from resource 2
Aug 26 23:19:48 localhost logger: openQRM-cmd-queu: Running Command with token 64d478dcac6670e5fb000e7c4954863b 1. retry : /usr/lib/openqrm/bin/dbclient -I 0 -K 10 -y -i /usr/lib/openqrm/etc/dropbear/dropbear_rsa_host_key -p 1667 root@192.168.42.243 "/usr/lib/openqrm/bin/openqrm-cmd /usr/lib/openqrm/plugins/xen/bin/openqrm-xen post_vm_list -u openqrm -p openqrm"
Aug 26 23:19:52 localhost logger: openQRM-cmd-queu: ERROR executing command with token 64d478dcac6670e5fb000e7c4954863b 2. retry : /usr/lib/openqrm/bin/dbclient -I 0 -K 10 -y -i /usr/lib/openqrm/etc/dropbear/dropbear_rsa_host_key -p 1667 root@192.168.42.243 "/usr/lib/openqrm/bin/openqrm-cmd /usr/lib/openqrm/plugins/xen/bin/openqrm-xen post_vm_list -u openqrm -p openqrm" -----
Aug 26 23:19:52 localhost logger: Host '192.168.42.243' key accepted unconditionally.
Aug 26 23:19:52 localhost logger: (fingerprint md5 64:d5:c7:8e:7a:11:08:3f:43:bc:3c:2b:bf:4a:c8:ce)
Aug 26 23:19:52 localhost logger: root@192.168.42.243's password: root@192.168.42.243's password: root@192.168.42.243's password: root@192.168.42.243's password: root@192.168.42.243's password: root@192.168.42.243's password: root@192.168.42.243's password: root@192.168.42.243's password: root@192.168.42.243's password: root@192.168.42.243's password: /usr/lib/openqrm/bin/dbclient: connection to root@192.168.42.243:1667 exited: remote closed the connection