i needed to connect to a juniper network connect vpn, but i didn't know the exact format of username, realm, hostname, and i wasn't sure exactly which password. this script uses Pexpect to try all combinations until it works.

juniper_brute_force.py

#!/usr/bin/env python2
# must be run from your ~/.juniper_networks otherwise you get:
# Failed to load the ncui library.\nQuitting.
# see also http://htnhan.blogspot.com/2013/07/juniper-network-connect-on-arch-linux.html

import pexpect
import time
from itertools import product
hosts = ['']
users = ['youruser' , '..']
realms = ['-r foo', ..]
passes = ['']

error_104 = 'ncapp> Failed to connect/authenticate with IVE. Error 104'
error_hostname = 'Error unable to resolve host'
def test(combo):
    host = combo[0]
    user = combo[1]
    realm = combo[2]
    passw = combo[3]

    cmd = "/opt/bin32-jre/bin/java -jar NC.jar -h %s -u %s -f <key>.der %s -L 5" % (host, user, realm)
    print "TESTING", cmd
    child = pexpect.spawn (cmd)
    child.expect ('Password:')
    time.sleep(0.1)
    child.sendline (passw)
    index = child.expect([error_104, pexpect.EOF, error_hostname])
    if index == 0:
        print error_104
    elif index == 1:
        print 'DUNNO!! what happend. output:'
        print child.before
    elif index == 2:
        print error_hostname
for i, combo in enumerate(product(hosts, users, realms, passes)):
    print "TESTING %i" % i, combo
    test(combo)