Remote control with telnetlib (Python recipe)

Remote control with telnetlib (Python recipe)

Send commands to one or more logins using Python’s standard telnetlib module.

auto_telnet.py - remote control via telnet

import os, sys, string, telnetlib
from getpass import getpass

class AutoTelnet:
def init(self, user_list, cmd_list, **kw):
self.host = kw.get(‘host’, ‘localhost’)
self.timeout = kw.get(‘timeout’, 600)
self.command_prompt = kw.get(‘command_prompt’, “$ “)
self.passwd = {}
for user in user_list:
self.passwd[user] = getpass(“Enter user ‘%s’ password: “ % user)
self.telnet = telnetlib.Telnet()
for user in user_list:
self.telnet.open(self.host)
ok = self.action(user, cmd_list)
if not ok:
print “Unable to process:”, user
self.telnet.close()

def action(self, user, cmd_list):
    t = self.telnet
    t.write("\n")
    login_prompt = "login: "
    response = t.read_until(login_prompt, 5)
    if string.count(response, login_prompt):
        print response
    else:
        return 0
    password_prompt = "Password:"
    t.write("%s\n" % user)
    response = t.read_until(password_prompt, 3)
    if string.count(response, password_prompt):
        print response
    else:
        return 0
    t.write("%s\n" % self.passwd[user])
    response = t.read_until(self.command_prompt, 5)
    if not string.count(response, self.command_prompt):
        return 0
    for cmd in cmd_list:
        t.write("%s\n" % cmd)
        response = t.read_until(self.command_prompt, self.timeout)
        if not string.count(response, self.command_prompt):
            return 0
        print response
    return 1

if name == ‘main‘:
basename = os.path.splitext(os.path.basename(sys.argv[0]))[0]
logname = os.environ.get(“LOGNAME”, os.environ.get(“USERNAME”))
host = ‘localhost’
import getopt
optlist, user_list = getopt.getopt(sys.argv[1:], ‘c:f:h:’)
usage = “””
usage: %s [-h host] [-f cmdfile] [-c “command”] user1 user2 …
-c command
-f command file
-h host (default: ‘%s’)

Example: %s -c “echo $HOME” %s
“”” % (basename, host, basename, logname)
if len(sys.argv) < 2:
print usage
sys.exit(1)
cmd_list = []
for (opt, optarg) in optlist:
if opt == ‘-f’:
for r in open(optarg).readlines():
if string.rstrip(r):
cmd_list.append(r)
elif opt == ‘-c’:
command = optarg
if command[0] == ‘“‘ and command[-1] == ‘“‘:
command = command[1:-1]
cmd_list.append(command)
elif opt == ‘-h’:
host = optarg
autoTelnet = AutoTelnet(user_list, cmd_list, host=host)

Python’s telnetlib permits users to easily automate access to telnet servers, even from non-Unix machines.

As an alternative to the popen() functions, telnetlib is probably a handy technique to have in your sysadmin toolbox.

Production code will generally be more robust, but this example should be enough to get anyone started in the right direction.