diff --git a/.env.example b/.env.example
index b55a826..1ef3d70 100644
--- a/.env.example
+++ b/.env.example
@@ -2,3 +2,6 @@ DATABASE_URL="postgresql://postgres:postgres@localhost:5432/mtc_reverse_proxy?sc
 PORT=4000
 FRONTEND_ORIGINS="http://localhost:5173,http://127.0.0.1:5173"
 REVERSE_PROXY_TIMEOUT_MS=15000
+
+# key for the Hestia-Nginx-Reverse-Proxy agents (same on every server)
+AGENT_API_KEY=
diff --git a/src/routes.js b/src/routes.js
index b63a5ec..c516219 100644
--- a/src/routes.js
+++ b/src/routes.js
@@ -421,6 +421,7 @@ router.post("/services/:id/reverse-proxy", async (req, res, next) => {
       method,
       headers: {
         "content-type": "application/json",
+        ...(gateway && process.env.AGENT_API_KEY ? { "x-api-key": process.env.AGENT_API_KEY } : {}),
       },
       body: method === "GET" ? undefined : JSON.stringify(body || {}),
       signal: controller.signal,