Add proper regex to VPN graph URLs

coin/vpn/urls.py

@@ -7,6 +7,6 @@ urlpatterns = patterns(
     # the same as the "backend_name" of the model).
     url(r'^([0-9]+)$', VPNView.as_view(template_name="vpn/vpn.html"), name="openvpn_ldap"),
     url(r'^password/([0-9]+)$', VPNGeneratePasswordView.as_view(template_name="vpn/password.html"), name="generate_password"),
-    url(r'^graph/(?P<vpn_id>.+)/(?P<period>[a-z]+)$', get_graph, name="get_graph"),
-    url(r'^graph/(?P<vpn_id>.+)$', get_graph, name="get_graph"),
+    url(r'^graph/(?P<vpn_id>[0-9]+)/(?P<period>[a-z]+)$', get_graph, name="get_graph"),
+    url(r'^graph/(?P<vpn_id>[0-9]+)$', get_graph, name="get_graph"),
 )