[ Python 範例代碼 ] Testing TCP connections

Source From Here 
Here’s a quick snippet of python code that attempts to establish a TCP connection and reports whether it was successful or not. Netcat is a lot better suited for this role, but sometimes you may not be able to install it. In these situations this little script can come in handy: 

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1. #!/usr/bin/env python  
2.   
3. import socket  
4. import time  
5. from time import sleep  
6.   
7. HOST=""  
8. PORT=""  
9. TIMEOUT=1.0  
10. WAIT = 1  
11.   
12. while True:  
13.     try:  
14.         s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)  
15.         s.settimeout(TIMEOUT)  
16.         s.connect((HOST, PORT))  
17.         print "[%s] Connection established" % time.strftime("%H:%M:%S")  
18.         time.sleep(1)  
19.         s.close()  
20.     except:  
21.         print "[%s] Cannot connect" % time.strftime("%H:%M:%S")  
22.         sleep(WAIT)  # Sleep in sec before retry  

Supplement 
* Python Stdlib - socket — Low-level networking interface 
* [ Python 文章收集 ] 時間信息的獲取與表示簡介 
* [Python Std Library] Data Types : datetime — Basic date and time types