client keepalive

client/index.js

@@ -9,6 +9,7 @@ const net = require('net');
 const { Tun } = require('tuntap2');
 const { encrypt, decrypt } = require('../encryption');
 const IP = require('ip-packet');
+const { randomFill, randomFillSync } = require('crypto');
 const sock = dgram.createSocket('udp4');
 
 const tun = new Tun();
@@ -79,4 +80,24 @@ function authenticateAndCheck() {
     }, 2000);
 }
 
+function keepAlive() {
+    var buff = Buffer.alloc(64);
+    randomFillSync(buff);
+    buff[0] = 0x60; // actually you can send anything just make sure that buff[0] >> 4 !== 4
+    sock.send(
+        encrypt(
+            buff,
+            config.privateKey,
+            config.iv,
+            config.algorithm
+        ),
+        config.port,
+        config.endpoint
+    );
+}
+
 authenticateAndCheck();
+
+setInterval(() => {
+    keepAlive();
+}, 15000);