Update the MAAS proxy to only allow source addresses from the POD management network

Change-Id: Idb27386d284f294193248020a391a4cb17e0d0f1
(cherry picked from commit acd218afbc1751147572d9c37c1f62f00c78da73)
diff --git a/roles/maas/tasks/main.yml b/roles/maas/tasks/main.yml
index c5c4642..f9cae50 100644
--- a/roles/maas/tasks/main.yml
+++ b/roles/maas/tasks/main.yml
@@ -197,6 +197,21 @@
   tags:
     - switch_support
 
+- name: Disable Proxy Access To All
+  become: yes
+  replace:
+    dest: /usr/share/maas/maas-proxy.conf
+    regexp: '^(acl localnet src all.*)$'
+    replace: '# \1'
+
+- name: Only Allow Proxy Access To POD Management Network
+  become: yes
+  lineinfile:
+    insertafter: '^# acl localnet src all'
+    line: "acl localnet src {{ networks.management }} # Only allow the POD management network to use proxy"
+    dest: /usr/share/maas/maas-proxy.conf
+    state: present
+
 - name: Restart MAAS Services
   become: yes
   service: