threads/sockets quick question.

this script should create individual threads to scan a range of IP
addresses, but it doesnt, it simple ... does nothing. it doesnt hang
over anything, the thread is not being executed, any ideas anyone?
It's because of the bugs. Nothing happens because

threading < MAX_THREADS

is always false. You are comparing a module to an int. Next,
you never create any instances of scanThread. Next the local
variables of scan() are not visible in scanThread.run().
--
--Bryan

import socket
import threading
import traceback
MAX_THREADS = 50
class scanThread(threading.Thread):
def run(self):
try:
ss = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
ss.connect((ip, port_counter))
print "%s | %d OPEN" % (ip, port_counter)
ss.close()
print "scanned: ",port_counter,"\n"
except:
traceback.print_exc()
# end class -------------------
def scan(ip, begin, end):
port_counter = 0
for port_counter in range(begin, end):
while threading < MAX_THREADS:
scanThread().start()
# end function -------------------
scan("localhost", 0, 10000)

Next, you never create any instances of scanThread.

BO> ed wrote:

this script should create individual threads to scan a range of IP
addresses, but it doesnt, it simple ... does nothing. it doesnt hang
over anything, the thread is not being executed, any ideas anyone?

BO> It's because of the bugs. Nothing happens because BO> threading < MAX_THREADS BO> is always false. You are comparing a module to an int. Next,
BO> you never create any instances of scanThread. Next the local
BO> variables of scan() are not visible in scanThread.run().

import socket
import threading
import traceback
class scanThread(threading.Thread):
def run(self):
try:
ss = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
ss.connect((ip, port_counter))
print "%s | %d OPEN" % (ip, port_counter)
ss.close()
print "scanned: ",port_counter,"\n"
except:
traceback.print_exc()
# end class -------------------
def scan(ip, thebegin, theend):
global ip
global thebegin
global theend
port_counter = 0
All meaningless...

port_counter is redefined in the /for/ loop itself, so there is no
need to preset it to 0.

/global/ only makes items from OUTSIDE a function visible within the
function -- but your items ARE visible inside since they are the
arguments passed in... The class has no visibility to them.

The other problem I see is that... Depending on how the scheduler
operates, you could easily have port_counter CHANGE value between the
creation of the task, and the task actually trying to access it. Of
course, since IP and port_counter are not visible within the task, you
are attempting create a connection on (None, None).
for port_counter in range(thebegin, theend):
scanThread().start()
# end function -------------------
scan("localhost", 0, 10000)

How would I handle this? Pseudo-code (I don't have time to really
create this)...
job_queue = Queue.Queue(max_threads)

for j in range(max_threads):
#create and start a thread

for p in range(theBegin, theEnd):
job_queue.put((ip, p))

for j in range(max_threads):
job_queue.put("DIE!")
-=-=-=-=-
And each thread basically consists of:

global job_queue
while True:
param = job_queue.get()
if param == "DIE!": break
try:
ss = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
ss.connect(param)
print "%s | %d OPEN" % param
ss.close()
print "scanned: %s \n" % param[1]
except:
traceback.print_exc()

In words: Create a global communication channel (the queue) from
which each task obtains its next assignment. Create all 50 (or whatever
limit you define) tasks -- each task will wait until an entry is
available on the queue, then process that entry, exiting if the entry is
the shutdown criteria. Main process then shoves assignments onto the
queue as fast as it can (up to the backlog limit -- you could have 50
tasks doing connections, and the main could have the next 50 assignments
queued). Finally, queue up enough shutdown messages so that each task is
assured of receiving at one.
-- ================================================== ============ <
wl*****@ix.netcom.com | Wulfraed Dennis Lee Bieber KD6MOG <
wu******@dm.net | Bestiaria Support Staff <
================================================== ============ <
Home Page: <http://www.dm.net/~wulfraed/> <
Overflow Page: <http://wlfraed.home.netcom.com/> <

import socket
import threading
import traceback def scan(ip, thebegin, theend):
global ip
global thebegin
global theend
Making parameters global is a bad idea (I think). Moreover, thebegin and
theend aren't used in scanThread. And port_counter still isn't passed.
Better give all required data as parameters to the scanThread constructor.

Something like:

class scanThread(threading.Thread):
def __init__(self, ip, port):
self.ip, self.port = ip, port
def run(self):
... use self.ip and self.port instead of ip and port_counter
port_counter = 0
for port_counter in range(thebegin, theend):
scanThread().start() scanThread(ip, port_number).start() # end function -------------------
scan("localhost", 0, 10000)

Bryan Olson wrote:

Next, you never create any instances of scanThread.

one would think that the "scanThread()" part of

scanThread().start()

would do exactly that.

localhost | 135 OPEN
scanned: 135

Traceback (most recent call last):
File "E:/*******.py", line 16, in -toplevel-
thread.start_new_thread(scan, (ip, port))
error: can't start new thread
localhost | 1027 OPEN scanned: 1027
localhost | 1029 OPEN
scanned: 1029

From where do you get port_counter in method run() of scanThread? (this

this script should create individual threads to scan a range of IP
addresses, but it doesnt, it simple ... does nothing. it doesnt hang
over anything, the thread is not being executed, any ideas anyone?
[SNIP]
while threading < MAX_THREADS:
scanThread().start()

import threading
MAX_THREADS = 50
threading < MAX_THREADS