How can I know if a certain port is open/closed on linux ubuntu, not a remote system, using python? How can I list these open ports in python?
- Netstat: Is there a way to integrate netstat output with python?
You can using the socket module to simply check if a port is open or not.
It would look something like this.
import socket
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
result = sock.connect_ex(('127.0.0.1',80))
if result == 0:
print "Port is open"
else:
print "Port is not open"
sock.close()
If you want to use this in a more general context, you should make sure, that the socket that you open also gets closed. So the check should be more like this:
import socket
from contextlib import closing
def check_socket(host, port):
with closing(socket.socket(socket.AF_INET, socket.SOCK_STREAM)) as sock:
if sock.connect_ex((host, port)) == 0:
print "Port is open"
else:
print "Port is not open"
For me the examples above would hang if the port wasn't open. Line 4 shows use of settimeout to prevent hanging
import socket
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.settimeout(2) #2 Second Timeout
result = sock.connect_ex(('127.0.0.1',80))
if result == 0:
print 'port OPEN'
else:
print 'port CLOSED, connect_ex returned: '+str(result)
If you only care about the local machine, you can rely on the psutil package. You can either:
Check all ports used by a specific pid:
proc = psutil.Process(pid) print proc.connections()Check all ports used on the local machine:
print psutil.net_connections()
It works on Windows too.
Netstat tool simply parses some /proc files like /proc/net/tcp and combines it with other files contents. Yep, it's highly platform specific, but for Linux-only solution you can stick with it. Linux kernel documentation describes these files in details so you can find there how to read them.
Please also notice your question is too ambiguous because "port" could also mean serial port (/dev/ttyS* and analogs), parallel port, etc.; I've reused understanding from another answer this is network port but I'd ask you to formulate your questions more accurately.
In case when you probing TCP ports with intention to listen on it, it’s better to actually call listen. The approach with tring to connect don’t 'see' client ports of established connections, because nobody listen on its. But these ports cannot be used to listen on its.
import socket
def check_port(port, rais=True):
""" True -- it's possible to listen on this port for TCP/IPv4 or TCP/IPv6
connections. False -- otherwise.
"""
try:
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.bind(('127.0.0.1', port))
sock.listen(5)
sock.close()
sock = socket.socket(socket.AF_INET6, socket.SOCK_STREAM)
sock.bind(('::1', port))
sock.listen(5)
sock.close()
except socket.error as e:
return False
if rais:
raise RuntimeError(
"The server is already running on port {0}".format(port))
return True
Just added to mrjandro's solution a quick hack to get rid of simple connection errors / timeouts.
You can adjust the threshold changing max_error_count variable value and add notifications of any sort.
import socket
max_error_count = 10
def increase_error_count():
# Quick hack to handle false Port not open errors
with open('ErrorCount.log') as f:
for line in f:
error_count = line
error_count = int(error_count)
print "Error counter: " + str(error_count)
file = open('ErrorCount.log', 'w')
file.write(str(error_count + 1))
file.close()
if error_count == max_error_count:
# Send email, pushover, slack or do any other fancy stuff
print "Sending out notification"
# Reset error counter so it won't flood you with notifications
file = open('ErrorCount.log', 'w')
file.write('0')
file.close()
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.settimeout(2)
result = sock.connect_ex(('127.0.0.1',80))
if result == 0:
print "Port is open"
else:
print "Port is not open"
increase_error_count()
And here you find a Python 3 compatible version (just fixed print syntax):
import socket
max_error_count = 10
def increase_error_count():
# Quick hack to handle false Port not open errors
with open('ErrorCount.log') as f:
for line in f:
error_count = line
error_count = int(error_count)
print ("Error counter: " + str(error_count))
file = open('ErrorCount.log', 'w')
file.write(str(error_count + 1))
file.close()
if error_count == max_error_count:
# Send email, pushover, slack or do any other fancy stuff
print ("Sending out notification")
# Reset error counter so it won't flood you with notifications
file = open('ErrorCount.log', 'w')
file.write('0')
file.close()
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.settimeout(2)
result = sock.connect_ex(('127.0.0.1',80))
if result == 0:
print ("Port is open")
else:
print ("Port is not open")
increase_error_count()
Please check Michael answer and vote for it. It is the right way to check open ports. Netstat and other tools are not any use if you are developing services or daemons. For instance, I am crating modbus TCP server and client services for an industrial network. The services can listen to any port, but the question is whether that port is open? The program is going to be used in different places, and I cannot check them all manually, so this is what I did:
from contextlib import closing
import socket
class example:
def __init__():
self.machine_ip = socket.gethostbyname(socket.gethostname())
self.ready:bool = self.check_socket()
def check_socket(self)->bool:
result:bool = True
with closing(socket.socket(socket.AF_INET, socket.SOCK_STREAM)) as sock:
modbus_tcp_port:int = 502
if not sock.connect_ex((self.machine_ip, modbus_tcp_port)) == 0:
result = False
return result
Here's a fast multi-threaded port scanner:
from time import sleep
import socket, ipaddress, threading
max_threads = 50
final = {}
def check_port(ip, port):
try:
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) # TCP
#sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) # UDP
socket.setdefaulttimeout(2.0) # seconds (float)
result = sock.connect_ex((ip,port))
if result == 0:
# print ("Port is open")
final[ip] = "OPEN"
else:
# print ("Port is closed/filtered")
final[ip] = "CLOSED"
sock.close()
except:
pass
port = 80
for ip in ipaddress.IPv4Network('192.168.1.0/24'):
threading.Thread(target=check_port, args=[str(ip), port]).start()
#sleep(0.1)
# limit the number of threads.
while threading.active_count() > max_threads :
sleep(1)
print(final)
来源：https://stackoverflow.com/questions/19196105/how-to-check-if-a-network-port-is-open-on-linux