problem in skiping a line in the text file

I have a code which takes backup from my cisco switches. It reads a text file containing switches’ IPs line by line, connect to each IP and takes backup from that switch. Here is the code:

import sys
import time
import paramiko 
import os
import cmd
import datetime

now = datetime.datetime.now()
user = input("Enter username:")
password = input("Enter Paswd:")
enable_password = input("Enter enable pswd:")
port=22
f0 = open('myswitches.txt')
for ip in f0.readlines():
       ip = ip.strip()
       filename_prefix ='/Users/apple/Documents' + ip 
       ssh = paramiko.SSHClient()
       ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
       ssh.connect(ip,port, user, password, look_for_keys=False)
       chan = ssh.invoke_shell()
       time.sleep(2)
       chan.send('enable\n')
       chan.send(enable_password +'\n')
       time.sleep(1)
       chan.send('term len 0\n')
       time.sleep(1)
       chan.send('sh run\n')
       time.sleep(20)
       output = chan.recv(999999)
       filename = "%s_%.2i%.2i%i_%.2i%.2i%.2i" % (ip,now.year,now.month,now.day,now.hour,now.minute,now.second)
       f1 = open(filename, 'a')
       f1.write(output.decode("utf-8") )
       f1.close()
       ssh.close() 
       f0.close()

The problem is that if the credentials of a switch is different, I receive this error and the program terminates. Here is the error:

paramiko.ssh_exception.AuthenticationException: Authentication failed.

How can I change this code so that in case the credentials of a switch is different, skip that line of the text file and try the next switch.

>Solution :

You can use try-except clause, like this:

from paramiko.ssh_exception import AuthenticationException

for ip in f0.readlines():
    try:
        ip = ip.strip()
        # The rest of the code
        # ...
    except AuthenticationException:
        print("Skipped")