• https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Virtualization_Host_Configuration_and_Guest_Installation_Guide/sect-Virtualization_Host_Configuration_and_Guest_Installation_Guide-Host_Installation-Installing_KVM_packages_on_an_existing_Red_Hat_Enterprise_Linux_system.html

[root@localhost ~]# yum groupinstall Virtualization
[root@localhost ~]# yum groupinstall "Virtualization Client"

[root@localhost ~]# service libvirtd status

[root@localhost ~]# qemu-img create -f qcow2 /vm/kvm/pfsense.qcow2 10G


[root@localhost iso]# virt-install --vcpus=1 --ram=1024 --name=pfsense --file=/vm/kvm/pfsense.qcow2 --cdrom=/vm/iso/pfSense-CE-2.3.2-RELEASE-amd64.iso --hvm --vnc --network bridge:virbr0

[root@localhost ~]# brctl show
bridge name	bridge id		STP enabled	interfaces
virbr0		8000.5254005d4f0b	yes		virbr0-nic
							vnet0
[root@localhost ~]# ip addr
...
3: virbr0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP qlen 1000
    link/ether 52:54:00:5d:4e:0a brd ff:ff:ff:ff:ff:ff
    inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0
       valid_lft forever preferred_lft forever
4: virbr0-nic: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast master virbr0 state DOWN qlen 1000
    link/ether 52:54:00:5d:4e:0a brd ff:ff:ff:ff:ff:ff
6: vnet0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master virbr0 state UNKNOWN qlen 1000
    link/ether fe:54:00:ad:70:82 brd ff:ff:ff:ff:ff:ff
    inet6 fe80::fc54:ff:fead:7082/64 scope link 
       valid_lft forever preferred_lft forever



[root@localhost ~]# nmap -sP 192.168.122.0/24

Starting Nmap 6.40 ( http://nmap.org ) at 2016-12-18 13:04 CET
Nmap scan report for 192.168.122.148
Host is up (0.00021s latency).
MAC Address: 52:54:00:AD:70:82 (QEMU Virtual NIC)
Nmap scan report for 192.168.122.1
Host is up.
Nmap done: 256 IP addresses (2 hosts up) scanned in 4.68 seconds
[root@localhost ~]# nmap 192.168.122.148

Starting Nmap 6.40 ( http://nmap.org ) at 2016-12-18 13:05 CET
Nmap scan report for 192.168.122.148
Host is up (0.00030s latency).
Not shown: 997 filtered ports
PORT    STATE SERVICE
22/tcp  open  ssh
80/tcp  open  http
443/tcp open  https
MAC Address: 52:54:00:AD:70:82 (QEMU Virtual NIC)

https://wiki.libvirt.org/page/VirtualNetworking

[root@localhost ~]# virsh net-dumpxml default
<network>
  <name>default</name>
  <uuid>048b8b48-18f5-4100-a708-c19df66bfabd</uuid>
  <forward mode='nat'>
    <nat>
      <port start='1024' end='65535'/>
    </nat>
  </forward>
  <bridge name='virbr0' stp='on' delay='0'/>
  <mac address='52:54:00:5d:4f:0b'/>
  <ip address='192.168.122.1' netmask='255.255.255.0'>
    <dhcp>
      <range start='192.168.122.2' end='192.168.122.254'/>
    </dhcp>
  </ip>
</network>

locatio of xml file

[root@localhost ~]# ls  /etc/libvirt/qemu/networks/
autostart  default.xml