在 telnetlib 超时后让 python 3 代码继续

Question

I'm trying til load a file with IP addresses, telnet to them, send some commands and save the output.I got it working and the output looks as expected.

My problem is, if there is an IP address in the file that in unreachable and telnetlib times out. Then the complete script stops. I would like to ignore the IP address that timed out and continue with the rest of the file.

#!/usr/bin/env python3

import pexpect
import getpass
import telnetlib
import socket

ipfile = input("Enter site (IP address file): ")
user = input("Enter username: ")
password = getpass.getpass("Enter password")
outputfile = ((ipfile)+".output")

f = open(outputfile, 'w')
f.write("")
f.close()

with open(ipfile) as ips:
   all_ips = [x.rstrip() for x in ips] # get all ips in a list and strip newline
for ip in all_ips:
   tn = telnetlib.Telnet(ip,23,2)
   tn.read_until(b"Username: ")
   tn.write(user.encode('ascii') + b"\n")
   if password:
     tn.read_until(b"Password: ")
     tn.write(password.encode('ascii') + b"\n")
     tn.write(b"term len 0\n")
     tn.write(b"sh inven\n")
     tn.write(b"logout\n")
#    print(tn.read_all().decode('ascii'))
     with open(outputfile,"ab") as f: #write to a file
       f.write(tn.read_all())                     

The error I get is

    Traceback (most recent call last):
  File "./test4.py", line 22, in <module>
    tn = telnetlib.Telnet(ip,  23,2)
  File "/usr/lib/python3.5/telnetlib.py", line 218, in __init__
    self.open(host, port, timeout)
  File "/usr/lib/python3.5/telnetlib.py", line 234, in open
    self.sock = socket.create_connection((host, port), timeout)
  File "/usr/lib/python3.5/socket.py", line 711, in create_connection
raise err
  File "/usr/lib/python3.5/socket.py", line 702, in create_connection
    sock.connect(sa)
socket.timeout: timed out

Answer 1

If you specifically want to catch a socket timeout you can do the following...

import socket
import telnetlib

ip = '127.0.0.1'

try:
    tn = telnetlib.Telnet(ip, 23, 2)
except socket.timeout:
    print("connection time out caught.")
    # handle error cases here...

Answer 2

I think I got it.

#!/usr/bin/env python3

import pexpect
import getpass
import telnetlib
import socket

ipfile = input("Enter site (IP address file): ")
user = input("Enter username: ")
password = getpass.getpass("Enter password: ")
outputfile = ((ipfile)+".output")

f = open(outputfile, 'w')
f.write("")
f.close()

with open(ipfile) as ips:
   all_ips = [x.rstrip() for x in ips] # get all ips in a list and strip newline
for ip in all_ips:
 try:
    tn = telnetlib.Telnet(ip,23,2)
    tn.read_until(b"Username: ")
    tn.write(user.encode('ascii') + b"\n")
    if password:
     tn.read_until(b"Password: ")
     tn.write(password.encode('ascii') + b"\n")
     tn.write(b"term len 0\n")
     tn.write(b"sh inven\n")
     tn.write(b"logout\n")
#    print(tn.read_all().decode('ascii'))
     with open(outputfile,"ab") as f: #write to a fil
       f.write(tn.read_all())
 except socket.timeout:
    print((ip)+" timeout")