portscanner.py

#!/usr/bin/env python3
"""PortScanner - simple TCP connect scanner (demo)
Usage: python3 portscanner.py <host> [start_port] [end_port]
"""
import sys, socket, time
def scan(host, start=1, end=1024, timeout=0.2):
    open_ports=[]
    for p in range(start, end+1):
        try:
            s=socket.socket()
            s.settimeout(timeout)
            s.connect((host,p))
            s.close()
            open_ports.append(p)
        except: pass
    return open_ports
def main():
    if len(sys.argv)<2:
        print('Usage: python3 portscanner.py <host> [start] [end]'); return
    host=sys.argv[1]
    s=int(sys.argv[2]) if len(sys.argv)>2 else 1
    e=int(sys.argv[3]) if len(sys.argv)>3 else 512
    t0=time.time()
    r=scan(host,s,e)
    print('Open ports:', r)
    print('Elapsed:', round(time.time()-t0,2), 's')
if __name__=='__main__': main()