Add option to configure the network address when using DHCP

README.md

@@ -488,6 +488,13 @@ An examples of network interface definitions:
     test_vm1.vm.network :private_network, :ip => "10.20.30.40"
   end
 
+  # Private network using DHCP and a custom network
+  config.vm.define :test_vm1 do |test_vm1|
+    test_vm1.vm.network :private_network,
+      :type => "dhcp",
+      :libvirt__network_address => '10.20.30.0'
+  end
+
   # Private network. Point to Point between 2 Guest OS using a TCP tunnel
   # Guest 1
   config.vm.define :test_vm1 do |test_vm1|
@@ -556,6 +563,7 @@ starts with `libvirt__` string. Here is a list of those options:
   network 'default' is used.
 * `:libvirt__netmask` - Used only together with `:ip` option. Default is
   '255.255.255.0'.
+* `:libvirt__network_address` - Used only when `:type` is set to `dhcp`. Only `/24` subnet is supported. Default is `172.28.128.0`.
 * `:libvirt__host_ip` - Address to use for the host (not guest).  Default is
   first possible address (after network address).
 * `:libvirt__dhcp_enabled` - If DHCP will offer addresses, or not. Used only

lib/vagrant-libvirt/action/create_networks.rb

@@ -240,8 +240,10 @@ module VagrantPlugins
         end
 
         def handle_dhcp_private_network(env)
-          net_address = '172.28.128.0'
+          net_address = @options[:libvirt__network_address]
+          net_address = '172.28.128.0' unless net_address
           network = lookup_network_by_ip(net_address)
+
           @interface_network = network if network
 
           # Do we need to create new network?