Python Script to Telnet Cisco Devices

As it is quite common to telnet into a router and run script to gather statistics or modify configurations. And python now is quite popular script. So today i wrote a script implementing logging in a cisco router and running command lines.

Below is the class, it is still simple as lots of exceptions i haven't taken into consideration. But it works well in most cases, i publish here and if have time i will try update it.

import telnetlib,time

TELNET_SLEEP_TIME = 1
class RouterDevice:
    host="localhost"    port=23    telnet = telnetlib.Telnet()
    #telnet.set_debuglevel(1000)    def __init__(self, host, port):
        self.host=host
        self.port=port

    def login(self, username, password):
        self.telnet.open(self.host, self.port, 1000)
        self.telnet.write("\n\n")
        time.sleep(TELNET_SLEEP_TIME)
        login_str = self.telnet.read_very_eager()
        print login_str,
        if login_str.endswith("Username: "):
            self.telnet.write(username+"\n")
            time.sleep(TELNET_SLEEP_TIME)
            login_str = self.telnet.read_very_eager()
            print login_str
        if login_str.endswith("Password: "):
            self.telnet.write(password+"\n")
            time.sleep(TELNET_SLEEP_TIME)
            login_str =  self.telnet.read_very_eager()
            print login_str
        if login_str.endswith("#"):
            return True        else:
            return False
    def command(self, cli):
        self.telnet.write(cli)
        time.sleep(TELNET_SLEEP_TIME)
        return self.telnet.read_very_eager()

    def close(self):
        print self.command("end\n"),
        print self.command("quit\n"),
        self.telnet.close()

Below is the demo on how to use the class

router1 = RouterDevice("localhost",30001)
if router1.login("cisco","cisco"):
    print router1.command("config terminal\n"),
    print router1.command("show running\n"),
router1.close()

I will keep publishing more and more useful knowledge on IP networking and also scripts. If you like please share this blog and follow me:)