diff --git a/shadowsocks-csharp/Data/abp.js b/shadowsocks-csharp/Data/abp.js
index 432a6385..7dd0246c 100644
--- a/shadowsocks-csharp/Data/abp.js
+++ b/shadowsocks-csharp/Data/abp.js
@@ -793,7 +793,22 @@ for (var i = 0; i < rules.length; i++) {
     defaultMatcher.add(Filter.fromText(rules[i]));
 }
 
+// PAC has no v6 support, it sucks
+var ip4Re = /^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$/
+
+var privateNet = [
+    ["10.0.0.0", "255.0.0.0"],
+    ["127.0.0.0", "255.0.0.0"],
+    ["172.16.0.0", "255.240.0.0"],
+    ["192.168.0.0", "255.255.0.0"],
+]
+
 function FindProxyForURL(url, host) {
+    if (host.match(ip4Re)) {
+        for (var i = 0; i < privateNet.length; i++) {
+            if (isInNet(host, privateNet[i][0], privateNet[i][1])) return direct;
+        }
+    }
     if (userrulesMatcher.matchesAny(url, host) instanceof BlockingFilter) {
         return proxy;
     }