diff --git a/README.md b/README.md
index 540c8b0..90e8754 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,7 @@
 # UdpSockerServer
 
-This program listen on an ip for UDP message and print them.
+This program listen on an ip for UDP message and print them. You can configure it to forward a message from an address
+to another, are blacklist a list of address.
 
 ## Build
 
@@ -21,6 +22,30 @@ cargo run
 
 Go to release and download the .exe file, then run it. A version for linux will be available soon.
 
+## Configuration
+
+You have a config.json file, like this: 
+````
+{
+  "forwarding": [
+    {
+      "from": "127.0.0.1:58545",
+      "to": "127.0.0.1:12346",
+      "doReverse": true
+    }
+  ],
+  "blacklist": [
+    "127.0.0.1:11111",
+    "127.0.0.1:55527"
+  ]
+}
+````
+
+The blacklist field is easy to understand: all addresses written are ignored by the server.
+The forwarding field is a list of object indicating that if the server receive a message from the address at "from" field
+it should send it back to "to" address. The doReverse field, if set to true, will permit that when we a message from "to" address,
+it is sent to "from" address.
+
 ## Authors
 
 @Namularbre