diff --git a/Basis/Functions.py b/Basis/Functions.py
new file mode 100644
index 0000000..31bb79e
--- /dev/null
+++ b/Basis/Functions.py
@@ -0,0 +1,68 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+import time
+import random
+import socket
+from Basis.Logger import logging
+
+
+def genFlag(length: int = 12) -> str:  # generate random task flag
+    flag = ''
+    for i in range(0, length):
+        tmp = random.randint(0, 15)
+        if tmp >= 10:
+            flag += chr(tmp + 87) # a ~ f
+        else:
+            flag += str(tmp) # 0 ~ 9
+    logging.debug('generate new flag -> ' + flag)
+    return flag
+
+
+def getAvailablePort(rangeStart: int = 41952, rangeEnd: int = 65535) -> int:  # get a available port
+    if rangeStart > rangeEnd or rangeStart < 1 or rangeEnd > 65535:
+        raise RuntimeError('invalid port range')
+    while True:
+        port = random.randint(rangeStart, rangeEnd)  # choose randomly
+        if checkPortStatus(port):
+            logging.debug('get new port -> %i' % port)
+            return port
+        time.sleep(0.1) # wait for 100ms
+
+
+def checkPortStatus(port: int) -> bool:  # check if the port is occupied
+    ipv4Tcp = None
+    ipv4Udp = None
+    ipv6Tcp = None
+    ipv6Udp = None
+    try:
+        ipv4Tcp = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        ipv4Udp = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+        ipv4Tcp.bind(('0.0.0.0', port))
+        ipv4Udp.bind(('0.0.0.0', port))
+        ipv4Tcp.close()
+        ipv4Udp.close()
+        ipv6Tcp = socket.socket(socket.AF_INET6, socket.SOCK_STREAM)
+        ipv6Udp = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM)
+        ipv6Tcp.bind(('::', port))
+        ipv6Udp.bind(('::', port))
+        ipv6Tcp.close()
+        ipv6Udp.close()
+        logging.debug('check status of port %i -> available' % port)
+        return True  # IPv4 TCP / IPv4 UDP / IPv6 TCP / IPv6 UDP are normal
+    except:
+        logging.debug('check status of port %i -> occupied' % port)
+        return False
+    finally:  # close socket
+        try:
+            ipv4Tcp.close()
+        except: pass
+        try:
+            ipv4Udp.close()
+        except: pass
+        try:
+            ipv6Tcp.close()
+        except: pass
+        try:
+            ipv6Udp.close()
+        except: pass