SSH accessibility check of multiple cisco router and save the output in a file

import paramiko
import time
import sys
import logging
import socket

remote_conn_pre = paramiko.SSHClient()
remote_conn_pre.set_missing_host_key_policy(paramiko.AutoAddPolicy())

f= open("output.txt","w+")

ips = [i.strip() for i in open("ip.txt")]

import logging
logging.getLogger('paramiko.transport').setLevel(logging.DEBUG)
paramiko.util.log_to_file("logs")

for ip in ips:
    try:
        remote_conn_pre.connect(ip, username='test', password='test', timeout=4, look_for_keys=False, allow_agent=False)
        remote_conn = remote_conn_pre.invoke_shell()
        print (ip + ' === Device Reachable')
        f.write(ip + ' === Device Reachable'"\n")
        time.sleep(2)
    except paramiko.AuthenticationException:
        print ip + ' === Bad credentials'
        f.write(ip + ' === Bad credentials'"\n")
        time.sleep(2)
    except paramiko.SSHException:
        print ip + ' === Issues with ssh service'
        f.write(ip + ' === Issues with ssh service'"\n")
        time.sleep(2)
    except socket.error:
        print ip + ' === Device unreachable'
        f.write(ip + ' === Device unreachable'"\n")
        time.sleep(2)
f.close()