diff --git a/backend/src/main.js b/backend/src/main.js
index 69f4ef9..b45f94c 100644
--- a/backend/src/main.js
+++ b/backend/src/main.js
@@ -4,7 +4,6 @@ const ukey = require("./FakeUKey")
 const cors = require('cors');
 const { killPortProcess } = require('kill-port-process');
 
-
 const app = express();
 // const port = 3000;
 const port = 8090;
@@ -47,18 +46,19 @@ app.post('/do', (req, res) => {
 
 
 (async () => {
+    // long running process running on a given port(s), e.g. a http-server
+    // takes a number, number[], string or string[]
+    // single port
+    await killPortProcess(8090);
 
-    try {
-        await killPortProcess(port);
-    } catch (e) {
-
-    }
-
-
-
-    app.listen(port, () => {
+    app.listen(port, "127.0.0.1", () => {
         console.log(`Server is running on port ${port}`);
+    }).on('error', (err) => {
+        if (err.code === 'ECONNREFUSED') {
+            console.log('端口监听失败。');
+        }
     });
-
 })();
 
+
+