Can python read Server names from a file

Question

Can python read Servernames / IP_addresses from a file rather than giving Servernames One by One, i did searched but did not find anything about it. I have below Script but this only takes the Single IP address or Server_name at a time. Wold appreciate any inputs..

This is for Linux and Pyhton version 2.6

#!/usr/bin/env python
import sys
sys.stderr = open('/dev/null')       # Silence silly warnings from paramiko
import paramiko as pm
sys.stderr = sys.__stderr__
import os

class AllowAllKeys(pm.MissingHostKeyPolicy):
    def missing_host_key(self, client, hostname, key):
        return

HOST = '192.1.10.1'
USER = 'karn'
PASSWORD = 'mypass'

client = pm.SSHClient()
client.load_system_host_keys()
client.load_host_keys(os.path.expanduser('~/.ssh/known_hosts'))
client.set_missing_host_key_policy(AllowAllKeys())
client.connect(HOST, username=USER, password=PASSWORD)

channel = client.invoke_shell()
stdin = channel.makefile('wb')
stdout = channel.makefile('rb')

stdin.write('''
hostname
uname -a
uptime
who
exit
''')
print stdout.read()

stdout.close()
stdin.close()
client.close()

Note: I want python to read the file which contains either Servers names or ip address in a squence .. example as below..

#  cat ServerList.txt
Server1
Server2
Server3
......

OR
# cat ServerList2
192.168.1.1
192.168.1.2
....

Below code is working now..appreciate your help guys

#!/usr/bin/python
import fileinput
import sys
import paramiko as pm
import os

sys.stderr = open('/dev/null')       # Silence silly warnings from paramiko
sys.stderr = sys.__stderr__


class AllowAllKeys(pm.MissingHostKeyPolicy):
    def missing_host_key(self, client, hostname, key):
        return

with open('/home/karn/PYTHN/host.txt', 'r') as f:
    for host in f:
        HOSTN = host.rstrip()
        USER = 'myuser'
        PASSWORD = 'mypass'

        client = pm.SSHClient()
        client.load_system_host_keys()
        client.load_host_keys(os.path.expanduser('~/.ssh/known_hosts'))
        client.set_missing_host_key_policy(AllowAllKeys())
        client.connect( HOSTN, username=USER, password=PASSWORD )

        channel = client.invoke_shell()
        stdin = channel.makefile('wb')
        stdout = channel.makefile('rb')

        stdin.write('''
        hostname
        lsb_release -a
        exit
        ''')
        print stdout.read()

        stdout.close()
        stdin.close()
        client.close()

Answer 1

You could use a csv file with 3 columns, one for HOST , USER and PASSWORD . Here are the official examples . In your code you'd for loop over the rows and extract the 3 fields in each row like in the example.

Answer 2

Here is an example for you, where I'd get Hostname and IP addresses from /etc/hosts :

with open ('/etc/hosts', 'r') as hosts:
   for line in hosts:
       l = line.split()
       if len(l) > 1:
          IP = l[0].rstrip()
          print IP
          Hostname = l[1].rstrip()
          print Hostname

Using with open makes sure that your file gets handled and closed properly by python.

Then read each line. It comes as a string, split() will return an array. Since I read from /etc/hosts, my first element is the IP address, second is the hostname. I use rstrip to make sure no extra characters get in the way.

From there you need to adapt whatever your file looks like.

Answer 3

after opening your file and reading each line, you can also try and extract by using a regex.

if you know your ip range:

matchIP = re.compile(r"192\.168\.1\.\d{0,225}$") #

and same with your server names