when virsh trying to connect to remote server by tcp protocl,

 

virsh -c qemu+tcp://host/system

 

it will shows:

error: unable to connect to server at 'host:16509': Connection refused
error: failed to connect to the hypervisor

To fix it,

1. change /etc/libvirt/libvirtd.conf

listen_tls = 0

listen_tcp=1

auth_tcp="none"

2. change /etc/default/libvirtd

libvirt_opts="-l"

3. reboot libvirtd

/etc/init.d/libvirtd restart

4. check tcp ports

netstat -lntp | grep libvirtd

ps aux | grep libvirtd