Read [archwiki](https://wiki.archlinux.org/index.php/Libvirt) and set libvirtd.conf:
```
listen_tls = 0
listen_tcp = 1
tcp_port = "16509"
listen_addr = "0.0.0.0"
auth_tcp = "none"
```
If requiring auth, set `auth_tcp = "sasl"` and read <https://github.com/retspen/webvirtmgr/wiki/Setup-TCP-authorization>
DO NOT use systemd service (it always crash with `--listen parameter not permitted with systemd activation sockets`). Directly run `sudo libvirtd --listen`