Raise an error if host IP is not found

lib/vagrant/action/builtin/handle_forwarded_port_collisions.rb

@@ -271,7 +271,11 @@ module Vagrant
             end
           else
             # Do a regular check
-            is_port_open?(host_ip, host_port)
+            if test_host_ip == "0.0.0.0" || ipv4_addresses.include?(test_host_ip)
+              is_port_open?(test_host_ip, host_port)
+            else
+              raise Errors::ForwardPortHostIPNotFound
+            end
           end
         end
 

lib/vagrant/errors.rb

@@ -400,6 +400,10 @@ module Vagrant
       error_key(:auto_empty, "vagrant.actions.vm.forward_ports")
     end
 
+    class ForwardPortHostIPNotFound < VagrantError
+      error_key(:host_ip_not_found, "vagrant.actions.vm.forward_ports")
+    end
+
     class ForwardPortCollision < VagrantError
       error_key(:collision_error, "vagrant.actions.vm.forward_ports")
     end

templates/locales/en.yml

@@ -2321,6 +2321,10 @@ en:
           forwarding: Forwarding ports...
           forwarding_entry: |-
             %{guest_port} (guest) => %{host_port} (host) (adapter %{adapter})
+          host_ip_not_found:
+            You are trying to forward a host IP that does not exist. Please set `host_ip`
+            to the address of an existing IPv4 network interface, or remove the option
+            from your port forward configuration.
           non_nat: |-
             VirtualBox adapter #%{adapter} not configured as "NAT". Skipping port
             forwards on this adapter.

test/unit/vagrant/action/builtin/handle_forwarded_port_collisions_test.rb

@@ -177,9 +177,11 @@ describe Vagrant::Action::Builtin::HandleForwardedPortCollisions do
   describe "#port_check" do
     let(:host_ip){ "127.0.0.1" }
     let(:host_port){ 8080 }
+    let(:test_ips) { [ "127.0.0.1", "192.168.1.7" ] }
 
     before do
       instance.instance_variable_set(:@machine, machine)
+      allow(instance).to receive(:ipv4_addresses).and_return(test_ips)
     end
 
     it "should check if the port is open" do
@@ -187,13 +189,8 @@ describe Vagrant::Action::Builtin::HandleForwardedPortCollisions do
       instance.send(:port_check, host_ip, host_port)
     end
 
-    context "when host_ip is 0.0.0.0" do
+    context "when host ip is 0.0.0.0" do
       let(:host_ip) { "0.0.0.0" }
-      let(:test_ips) { [ "127.0.0.1", "192.168.1.7" ] }
-
-      before do
-        allow(instance).to receive(:ipv4_addresses).and_return(test_ips)
-      end
 
       context "on windows" do
         let(:guest) { :windows }
@@ -221,5 +218,13 @@ describe Vagrant::Action::Builtin::HandleForwardedPortCollisions do
         end
       end
     end
+
+    context "when host ip does not exist" do
+      let(:host_ip) { "127.0.0.2" }
+
+      it "should raise an error" do
+        expect{ instance.send(:port_check, host_ip, host_port) }.to raise_error(Vagrant::Errors::ForwardPortHostIPNotFound)
+      end
+    end
   end
 end