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tac_plus/tacacs-F4.0.4.28/do_auth.py

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#!/usr/bin/python
# Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved
# Program I threw together to do the things tac_plus won't
# It allows very granular control. Please visit tacacs.org as
# this is continually updated
# History:
# Version 1.1
# Simple typo - a stray 's' botched a deny statement
# Version 1.2
# Did you know a firewall doesn't end it's commands with a <cr>?
# Version 1.3
# Needs a default user. If most of your users have the same access,
# and you have a default access in tac_plus.conf, you need it here as
# well.
# Version 1.4
# CRS doesn't send $address when in conf t
# Added -fix_crs_bug as as simple/stupid workaround
# Version 1.5
# Mistake in the example, thanks to aojea
# Version 1.6
# Added support for other services besides service=shell
# (ie - they work, by they match on IP/Source only. If you have examples of
# pairs other than cmd to match on, please bring them to my attention)
# Version 1.7
# Fixed reression
# Support for replacing av pairs
# Version 1.8
# Nexus support (tac_pair format different)
# Version 1.9
# Better Nexus Support
# Only send roles to Nexus
# Better av pair replacement
# TO DO (If anybody bothers to request them)
# Possible web front end - simple cgi shouldn't be too hard to write
# More work on tac_pairs - sniff wlc traffic
# Write a better option parser to ignore options not sent (See CRS Bug)
'''
do_auth.py [-options]
Version 1.9
do_auth is a python program I wrote to work as an authorization script for
tacacs to allow greater flexability in tacacs authentication. It allows
a user to be part of many predefined groups that can allow different
access to different devices based on ip, user, and source address.
Do not play with do_auth untill you have a firm grasp on tac_plus!
-u Username. Mandatory. $user
-i Ip address of user. Optional. If not specified, all host_ entries
are ignored and can be omitted. $address
**Note: If you use IOS-XR, you MUST add -fix_crs_bug after $address
due to a bug in IOS-XR
-d Device address. Optional. If not specified, all device_ entries
are ignored and can be omitted. $name
-f Config Filename. Default is do_auth.ini.
-l Logfile. Default is log.txt.
-D Debug mode. Allows you to call the program without reading
from stdin. Useful to test your configuration before going
live. Sets a default command of "show users wides".
Groups are assigned to users in the [users] section. A user must
be assigned to one or more groups, one per line. Groups are defined
in brackets, but can be any name. Each group can have up to 6 options
as defined below.
host_deny Deny any user coming from this host. Optional.
host_allow Allow users from this range. Mandatory if
-i is specified.
device_deny Deny any device with this IP. Optional.
device_permit Allow this range. Mandatory if -d is specified
command_deny Deny these commands. Optional.
command_permit Allow these commands. Mandatory.
av_pairs list of av pairs to replace if found. Optional - be careful
The options are parsed in order till a match is found. Obviously,
for login, the commands section is not parsed. If a match is not
found, or a deny is found, we move on to the next group. At the
end, we have an implicit deny if no groups match.
An simple example is as follows.
[users]
homer =
simpson_group
television_group
stimpy =
television_group
[simpson_group]
host_deny =
1.1.1.1
1.1.1.2
host_allow =
1.1.1.*
device_permit =
10.1.1.*
command_permit =
.*
[television_group]
host_allow =
.*
device_permit =
.*
command_permit =
show.*
Example tacacs line: after authorization "/usr/bin/python
/root/do_auth.pyc -i $address -fix_crs_bug -u $user -d $name -l /root/log.txt
-f /root/do_auth.ini"
(that's one line)
Example av_pair:
The following example will replace any priv-lvl with priv-lvl=1 ONLY if passed.
Think of "av_pairs" as a find/replace function.
av_pairs =
priv-lvl=1
Brocade has a brocade-privlvl which I like. It maps priv-lvl to
brocade-privlvl, but priv-lvl=1 results in interface privileges. Here
is an example of how to map to brocade-privlvl=5 which has no modification
rights. Unfortunately, it does require you to put in the IP's of your gear.
The following group would go before other groups:
[brocade_readonly]
host_allow =
.*
device_permit =
192.168.1.*
command_permit =
.*
av_pairs =
priv-lvl,brocade-privlvl=5
You could also put "priv-lvl=15,brocade-privlvl=5" or whatever your
tac_plus deamon is passing; as long as it's a match it accomplished the same
thing. In this example, we essentially replace the whole av_pair resulting
in the user having only read access. Alternatively, a good "disable account"
can be created by simpley doing:
av_pairs =
brocade-privlvl=5
This results in the brocades having read/only, and the Cisco's go into disable
because they don't understand it. (We're assuming that the user has no enable
account or the priv-lvl is pointless) You could also add a shell role for nexus,
which we will discuss next. (shell:roles="network-admin")
NEXUS - Due to a slight change in the nexus, do_auth is able to
discern if a device is a nexus or not. In tac_plus, do the following:
service = exec {
priv-lvl = 1
shell:roles=\"\\"network-operator\\""
idletime = 3
timeout = 15
}
after authorization <do_auth yada yada>
This configuration does NOT work without do_auth. However, WITH do_auth,
do_auth will only send shell:roles to Nexus switches, allowing your
other gear to work correctly. Simply put av_pairs in your do_auth, and
it will figure it out for you. (If not, it won't touch them. The logic is
simple: If (av_pairs in .ini): Then (do_stuff), Else (exit(2)- Don't modify 'em!))
Roles can also be modified in a do_auth group, as below:
av_pairs =
priv-lvl=15
shell:roles="network-admin"
Also of note, you MUST USE DOUBLE QUOTES to get tac_plus to correctly
pass "network-operator" in the service example above. UNLESS you are
modifying the key with do_auth in av_pairs - it will fix the quotes.
BUGS: You must know your regular expressions. If you enter a bad
expression, such as *. instead of .*, python re will freak out and
not evaluate the expression. (Thought about netaddr, but would you
really install it?)
CAVEATS: One group can not take away what another group grants via deny.
If a match is not found, it will go on to the next group. If a deny is
matched, it will go on to the next group.
Order is crucial - the groups should go from more specific to less
specific. In the above example, if television_group was put before
simpson_group, simpson_group would never be called because
televsion_group catches everything in device_permit.
HELP: If somebody has a WLC or other unknown network equipment, I
require some testing/sniffing done - thanks!!
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License version 3 or any
later version as published by the Free Software Foundation,
http://www.gnu.org/
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
Written by Dan Schmidt - Please visit tacacs.org to check for updates.
'''
from __future__ import print_function
from future import standard_library
standard_library.install_aliases()
from builtins import str
import sys,re,getopt,configparser
from time import strftime
# I really don't want to deal with these exceptions more than once
# filename is only used in log statements
def get_attribute(config, the_section, the_option, log_file, filename):
if not config.has_section(the_section):
log_file.write(strftime("%Y-%m-%d %H:%M:%S: ")
+ "Error: Section '%s' does not exist in %s\n"
% (the_section, filename))
sys.exit(1)
if not config.has_option(the_section, the_option):
log_file.write(strftime("%Y-%m-%d %H:%M:%S: ")
+ "Error: Option '%s' does not exist in section %s in file %s\n"
% (the_option, the_section, filename))
sys.exit(1)
#Should not have any exceptions - BUT, just in case
try:
attributes = config.get(the_section, the_option)
except configparser.NoSectionError:
log_file.write(strftime("%Y-%m-%d %H:%M:%S: ")
+ "Error: Section '%s' Doesn't Exist!\n"
% (the_section))
sys.exit(1)
except configparser.DuplicateSectionError:
log_file.write(strftime("%Y-%m-%d %H:%M:%S: ")
+ "Error: Duplicate section '%s'\n"
% (the_section))
sys.exit(1)
except configparser.NoOptionError:
log_file.write(strftime("%Y-%m-%d %H:%M:%S: ")
+ "Error: '%s' not found in section '%s\n'"
% (the_option, the_section))
sys.exit(1)
#To do: finish exceptions.
except configparser.ParsingError:
log_file.write(strftime("%Y-%m-%d %H:%M:%S: ")
+ "Error: Can't parse file '%s'! (You got me)\n"
% (filename))
sys.exit(1)
attributes = attributes.split('\n')
#Strip empty lines
attributes2 = []
for line in attributes:
if line:
attributes2.append(line)
return attributes2
# Can't make it part of get_attribute... oh well...
# We need someway to check to see if a username exists with out exit(1)
def check_username(config, log_file, user_name):
if not config.has_section('users'):
log_file.write(strftime("%Y-%m-%d %H:%M:%S: ")
+ "Error: users section doesn't exist!")
sys.exit(1)
if config.has_option('users', user_name):
return True
else:
return False
# If match item in our_list, true, else false
# Example - if deny section has a match for 10.1.1.1,
# return True, else False
# If the section doesn't exist, we assume an
# impicity deny/false
def match_it(the_section, the_option, match_item, config, log_file, filename):
if config.has_option(the_section,the_option):
our_list = get_attribute(config, the_section, the_option, log_file, filename)
for item in our_list:
#p = re.compile(item) Not necessary - we're only using it once
if re.match(item,match_item):
return True
return False
def main():
#Defaults
filename = "do_auth.ini"
log_name = "log.txt"
user_name = ""
ip_addr = ""
device = ""
is_debug = False
argv = sys.argv
try:
optlist, args = getopt.getopt(sys.argv[1:], 'i:u:f:l:d:?:D', ['fix_crs_bug','?', '-?', 'help', 'Help'])
except getopt.GetoptError as err:
print(str(err))
print(__doc__)
sys.exit(1)
for (i, j) in optlist:
if i == '-i':
ip_addr = j
elif i == '-u':
user_name = j
elif i == '-f':
filename = j
elif i == '-l':
log_name = j
elif i == '-d':
device = j
elif i in ('?', '-?', 'help', 'Help'):
print(__doc__)
sys.exit(1)
elif i == '-D':
is_debug = True
else:
print('Unknown option:', i)
sys.exit(1)
if len(argv) < 7:
print(__doc__)
sys.exit(1)
log_file = open (log_name, "a")
#DEBUG! We at least got CALLED
# log_file.write('Hello World!' + '\n')
#read AV pairs
av_pairs = []
if not (is_debug):
for line in sys.stdin:
av_pairs.append(line)
else:
#Default Debug command is "show users wide"
#Later versions will allow this to be set
av_pairs.append("service=shell\n")
av_pairs.append("cmd=show\n")
av_pairs.append("cmd-arg=users\n")
av_pairs.append("cmd-arg=wide\n")
av_pairs.append("cmd-arg=<cr>\n")
#DEBUG - print tac pairs
# for item in av_pairs:
# log_file.write(item)
# Function to make cmd's readable
# Not very good, but will do for now
# I don't use any other service other than shell to test!
the_command = ""
return_pairs = ""
if (av_pairs[0] == "service=shell\n"):
if av_pairs[1] == ("cmd=\n"): # #&*@ Nexus!
if len(av_pairs) > 2:
#DEBUG
# log_file.write('Nexus pairs found\n')
return_pairs = av_pairs[2:] #strip the "cmd=" for consistency
#Commands - Concatenate to a readable command
elif av_pairs[1].startswith("cmd="):
our_command = av_pairs[1].split("=")
the_command = our_command[1].strip('\n')
if len(av_pairs) > 2:
i = 2
our_command = av_pairs[i].split("=")
while not (our_command[1] == "<cr>\n"):
the_command = the_command + " " + our_command[1].strip('\n')
i = i + 1
if i == len(av_pairs): # Firewalls don't give a <cr>!!
break
our_command = av_pairs[i].split("=")
#DEBUG - We got the command
#log_file.write(the_command + '\n')
#Login - Get av_pairs to pass back to tac_plus
elif av_pairs[1].startswith("cmd*"): #Anybody know why it's "cmd*"?
if len(av_pairs) > 2:
return_pairs = av_pairs[2:] #You MUST strip the "cmd*" av-pair
# Definately not a Nexus, so strip any nexus pair
for item in return_pairs:
if item.startswith("shell:roles"):
return_pairs.remove(item)
else:
return_pairs = av_pairs
if not user_name:
log_file.write(strftime("%Y-%m-%d %H:%M:%S: ")
+ "Error: No username entered!\n")
sys.exit(1)
config = configparser.SafeConfigParser()
if not (filename in config.read(filename)):
log_file.write(strftime("%Y-%m-%d %H:%M:%S: ")
+ "Error: Can't open/parse '%s'\n"
% (filename))
sys.exit(1)
the_section = "users"
# If the user doesn't exist, just use the default settings
# Kind of a hack, but it works because we only get_attribute on user_name once.
# We have the : in there which we can use to split if required
if not check_username(config, log_file, user_name):
user_name = (user_name + ":(default)")
groups = get_attribute(config, "users", "default", log_file, filename)
else:
groups = get_attribute(config, "users", user_name, log_file, filename)
for this_group in groups:
if ip_addr:
if match_it(this_group, "host_deny", ip_addr, config, log_file, filename):
if this_group == groups[-1]:
log_file.write(strftime("%Y-%m-%d %H:%M:%S: ")
+ "User '%s' denied from source '%s' in '%s'->'%s'\n"
% (user_name, ip_addr, this_group, "host_deny"))
sys.exit(1)
else:
# HUM... afterthought. We need it to continue if more groups exist
continue
if not match_it(this_group, "host_allow", ip_addr, config, log_file, filename):
#Stupid IOS-XR
if ip_addr == "-fix_crs_bug":
pass
elif this_group == groups[-1]:
log_file.write(strftime("%Y-%m-%d %H:%M:%S: ")
+ "User '%s' not allowed from source '%s' in '%s'->'%s'\n"
% (user_name, ip_addr, this_group, "host_allow"))
sys.exit(1)
else:
continue
if device:
if match_it(this_group, "device_deny", device, config, log_file, filename):
if this_group == groups[-1]:
log_file.write(strftime("%Y-%m-%d %H:%M:%S: ")
+ "User '%s' denied access to device '%s' in '%s'->'%s'\n"
% (user_name, device, this_group, "device_deny"))
sys.exit(1)
else:
continue
if not match_it(this_group, "device_permit", device, config, log_file, filename):
if this_group == groups[-1]:
log_file.write(strftime("%Y-%m-%d %H:%M:%S: ")
+ "User '%s' not allowed access to device '%s' in '%s'->'%s'\n"
% (user_name, device, this_group, "device_permit"))
sys.exit(1)
else:
continue
# Attempt to modify return pairs
want_tac_pairs = False
if config.has_option(this_group, "av_pairs"):
temp_av_pairs = get_attribute(config, this_group, "av_pairs", log_file, filename)
i = 0
for item in return_pairs:
splt = item.split('=')
if len(splt) > 1:
#DEBUG
#for thing in splt:
# log_file.write('Thing:' + thing + '\n')
for item2 in temp_av_pairs:
item2 = item2.strip()
if item2.find(',') > -1:
splt2 = item2.split(',')
if len(splt2) > 1:
#splt3 = splt2[0].split('=')
if splt[0].find(splt2[0]) > -1:
want_tac_pairs = True
return_pairs[i] = ('%s' % splt2[1])
else:
splt2 = item2.split('=')
if len(splt2) > 1:
if splt[0] == splt2[0].strip(): # strip needed?
want_tac_pairs = True
#DEBUG
#log_file.write("Replacing pairs %s=%s\n" %
# (splt2[0].strip(),
# splt2[1].strip()))
return_pairs[i] = ('%s=%s' % (splt2[0].strip(),
splt2[1].strip()))
i = i + 1
# The previous 4 statements are to deny, it we passed them, proceed
# If we are logging in, return pairs, if not, go no to check the command
# Yes, simply printing them is how you return them
# First, let's make sure we're doing service = shell. If not, just
# allow it. I currently have little knowledge of cmd's sent by other
# services which is why this code is a little klugy.
if return_pairs:
splt = av_pairs[0].split('=') # Removed service in return_pairs
if len(splt) > 1:
if not splt[1].strip() == 'shell':
log_file.write(strftime("%Y-%m-%d %H:%M:%S: ")
+ "User '%s' granted non-shell access to device '%s' in group '%s' from '%s'\n"
% (user_name, device, this_group, ip_addr))
return_pairs = av_pairs[2:] # Cut the first two?
for item in return_pairs:
#DEBUG
# log_file.write("Returning:%s\n" % item.strip())
print(item.strip('\n'))
if want_tac_pairs:
#DEBUG
# log_file.write("Exiting status 2\n")
sys.exit(2)
else:
#DEBUG
# log_file.write("Exiting status 0\n")
sys.exit(0) # Don't even TRY to mess with the tac pairs
#Proceed with shell stuff
if not len(the_command) > 0:
#DEBUG
# log_file.write("not len(the_command) > 0\n")
for item in return_pairs:
#DEBUG
# log_file.write("Returning:%s\n" % item.strip())
print(item.strip('\n'))
log_file.write(strftime("%Y-%m-%d %H:%M:%S: ")
+ "User '%s' granted access to device '%s' in group '%s' from '%s'\n"
% (user_name, device, this_group, ip_addr))
sys.exit(2)
else: # Check command
if match_it(this_group, "command_deny", the_command, config, log_file, filename):
if this_group == groups[-1]:
log_file.write(strftime("%Y-%m-%d %H:%M:%S: ")
+ "User '%s' denied command '%s' to device '%s' in '%s'->'%s'\n"
% (user_name, the_command, device, this_group, "command_deny"))
sys.exit(1)
else:
continue
elif match_it(this_group, "command_permit", the_command, config, log_file, filename):
log_file.write(strftime("%Y-%m-%d %H:%M:%S: ")
+ "User '%s' allowed command '%s' to device '%s' in '%s'->'%s'\n"
% (user_name, the_command, device, this_group, "command_permit"))
sys.exit(0)
else: #exit & log if last group
if this_group == groups[-1]:
log_file.write(strftime("%Y-%m-%d %H:%M:%S: ")
+ "User '%s' not allowed command '%s' to device '%s' in any group\n"
% (user_name, the_command, device))
#Can't... remember why I added this given the implicit deny
sys.exit(1)
else:
continue
#implicit deny at the end
log_file.write(strftime("%Y-%m-%d %H:%M:%S: ")
+ "User '%s' not allowed access to device '%s' from '%s' in any group\n"
% (user_name, device, ip_addr))
sys.exit(1)
if __name__ == "__main__":
main()
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