# yum install -y virt-install qemu libvirt kvm seabios qemu-kvm

# systemctl enable --now libvirtd

# virsh net-list
 Name                 State      Autostart     Persistent
----------------------------------------------------------
 default              active     yes           yes

# virsh net-destroy default
Network default destroyed

# virsh net-undefine default
Network default has been undefined

# diff -u /etc/sysconfig/libvirtd{,.orig}
--- /etc/sysconfig/libvirtd     2019-06-29 04:51:15.601536416 +0000
+++ /etc/sysconfig/libvirtd.orig        2019-06-29 04:50:34.197483618 +0000
@@ -6,7 +6,7 @@

 # Listen for TCP/IP connections
 # NB. must setup TLS/SSL keys prior to using this
-LIBVIRTD_ARGS="--listen"
+#LIBVIRTD_ARGS="--listen"

# diff -u /etc/libvirt/libvirtd.conf{,.orig}
--- /etc/libvirt/libvirtd.conf  2019-06-29 04:52:59.835812187 +0000
+++ /etc/libvirt/libvirtd.conf.orig     2019-06-29 04:52:37.898775202 +0000
@@ -491,5 +491,3 @@
 # potential infinite waits blocking libvirt.
 #
 #ovs_timeout = 5
-listen_tls = 0
-listen_tcp = 1

# diff -u /etc/sasl2/libvirt.conf{,.orig}
--- /etc/sasl2/libvirt.conf     2019-06-29 05:27:42.096793960 +0000
+++ /etc/sasl2/libvirt.conf.orig        2019-06-29 04:55:13.358973492 +0000
@@ -18,7 +18,7 @@
 # To use GSSAPI requires that a libvirtd service principal is
 # added to the Kerberos server for each host running libvirtd.
 # This principal needs to be exported to the keytab file listed below
-mech_list: digest-md5
+mech_list: gssapi

 # If using a TLS socket or UNIX socket only, it is possible to
 # enable plugins which don't provide session encryption. The
@@ -37,9 +37,9 @@
 # instead need KRB5_KTNAME env var.
 # For modern Linux, and other OS, this should be sufficient
 #
-# keytab: /etc/libvirt/krb5.tab
+keytab: /etc/libvirt/krb5.tab

 # If using scram-sha-1 for username/passwds, then this is the file
 # containing the passwds. Use 'saslpasswd2 -a libvirt [username]'
 # to add entries, and 'sasldblistusers2 -f [sasldb_path]' to browse it
-sasldb_path: /etc/libvirt/passwd.db
+#sasldb_path: /etc/libvirt/passwd.db

# yum install cyrus-sasl-md5

# saslpasswd2 -a libvirt root
Password:
Again (for verification):

# sasldblistusers2 -f /etc/libvirt/passwd.db
root@test.example.net: userPassword

# systemctl restart libvirtd

# virsh -c qemu+tcp://localhost/system nodeinfo
Please enter your authentication name: root
Please enter your password:
CPU model:           x86_64
CPU(s):              48
CPU frequency:       2300 MHz
CPU socket(s):       1
Core(s) per socket:  12
Thread(s) per core:  2
NUMA cell(s):        2
Memory size:         134089036 KiB

# yum install cyrus-sasl-md5

# virsh -c qemu+tcp://192.168.0.74/system nodeinfo
Please enter your authentication name: root
Please enter your password:
CPU model:           x86_64
CPU(s):              24
CPU frequency:       2933 MHz
CPU socket(s):       1
Core(s) per socket:  6
Thread(s) per core:  2
NUMA cell(s):        2
Memory size:         67098420 KiB

# diff /etc/libvirt/libvirtd.conf{,.orig}
494,496d493
< listen_tls = 0
< listen_tcp = 1
< auth_tcp = "none"

# systemctl restart libvirtd

# virsh -c qemu+tcp://localhost/system nodeinfo
CPU model:           x86_64
CPU(s):              48
CPU frequency:       2300 MHz
CPU socket(s):       1
Core(s) per socket:  12
Thread(s) per core:  2
NUMA cell(s):        2
Memory size:         134089036 KiB

# ls -al /dev/kvm
0 crw------- 1 root root 10, 232 Jun 29 08:53 /dev/kvm

# chown root:kvm /dev/kvm

# chmod 660 /dev/kvm

# ls -al /dev/kvm
0 crw-rw---- 1 root kvm 10, 232 Jun 29 08:53 /dev/kvm