diff --git a/Protocol.md b/Protocol.md
index c026080..7b07d35 100644
--- a/Protocol.md
+++ b/Protocol.md
@@ -120,4 +120,6 @@ Here, a client send a 'ping' request to a server and the server reply with a 'po
 
 Each command is described in a dedicated page
 
-- TODO
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+> Note: ID is always omitted in a command description but present in reality
+
+- [PING](https://eveldee.ddns.net:1342/Eveldee/PlantBox/wiki/Ping)
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