CiscoConfParse Tutorial

Search your Cisco configurations with Python
Code repo on github
Documentation
Author: Mike Pennington <mike@pennington.net>
Date: 2019-02-25
This presentation created with landslide

Presenter Notes

Installation

Assume you're running linux and already have pip installed
The next command will download and install the latest version from pypi
Python2.7 - pip install -U ciscoconfparse
Python3.x - pip3 install -U ciscoconfparse

Presenter Notes

Example Configuration

The following examples will use this configuration:

! filename:exampleswitch.conf
!
hostname ExampleSwitch
!
interface GigabitEthernet 1/1
 switchport mode trunk
 shutdown
!
interface GigabitEthernet 1/2
 switchport mode access
 switchport access vlan 20
 switchport nonegotiate
 no cdp enable
!
interface GigabitEthernet 1/3
 no switchport
 ip address 192.0.2.1 255.255.255.0

Presenter Notes

Example: Find interfaces

Use find_objects() to give us a list of interface objects:

from ciscoconfparse import CiscoConfParse

# Parse the config into objects
parse = CiscoConfParse('exampleswitch.conf', syntax='ios')

# Iterate over all the interface objects
for intf_obj in parse.find_objects('^interface'):
    print("ciscoconfparse object: " + intf_obj)

Output:

ciscoconfparse object: <IOSCfgLine # 4 'interface GigabitEthernet 1/1'>
ciscoconfparse object: <IOSCfgLine # 8 'interface GigabitEthernet 1/2'>
ciscoconfparse object: <IOSCfgLine # 14 'interface GigabitEthernet 1/3'>

Presenter Notes

Example: Use object properties

Use intf_obj.children to iterate over an object's children:

from ciscoconfparse import CiscoConfParse

parse = CiscoConfParse('exampleswitch.conf', sytax='ios')

# Choose the first interface (parent) object
for intf_obj in parse.find_objects('^interface')[0:1]:
    print("Parent obj: " + str(intf_obj))

    # Iterate over all the child objects of that parent object
    for c_obj in intf_obj.children:
        print("Child obj :    " + str(c_obj))

Output:

Parent obj: <IOSCfgLine # 4 'interface GigabitEthernet 1/1'>
Child obj :    <IOSCfgLine # 5 ' switchport mode trunk' (parent is # 4)>
Child obj :    <IOSCfgLine # 6 ' shutdown' (parent is # 4)>

Presenter Notes

Example: Use object properties

Use intf_obj.text to get the object's configuration text

from ciscoconfparse import CiscoConfParse

parse = CiscoConfParse('exampleswitch.conf', syntax='ios')

# Choose the first interface (parent) object
for intf_obj in parse.find_objects('^interface')[0:1]:
    print(intf_obj.text)

Output:

interface GigabitEthernet 1/1

Presenter Notes

Example: Find shutdown interfaces

Use find_objects_w_child() to give us a list of shutdown interfaces:

from ciscoconfparse import CiscoConfParse

parse = CiscoConfParse('exampleswitch.conf', syntax='ios')

for intf_obj in parse.find_objects_w_child('^interface', '^\s+shutdown'):
    print("Shutdown: " + intf_obj.text)

Output:

Shutdown: interface GigabitEthernet1/1

Presenter Notes

Example: Extract an interface address

Use `re_match_iter_typed()` to extract values with a regex match group

from ciscoconfparse import CiscoConfParse

parse = CiscoConfParse('exampleswitch.conf', syntax='ios')

intf_obj = parse.find_objects('interface\s+GigabitEthernet1\/3$')

# Search children of GigabitEthernet1/3 for a regex match and return 
# the value matched in regex match group 1.  If there is no match, return a
# default value: ''
intf_ip_addr = intf_obj.re_match_iter_typed(
    r'ip\saddress\s(\d+\.\d+\.\d+\.\d+)\s', result_type=str,
    group=1, default='')
print("ip addr: " + intf_ip_addr)

Output:

ip addr: 192.0.2.1

Presenter Notes

Using `factory=True`

Parsing with CiscoConfParse('exampleswitch.conf', syntax='ios', factory=True) gives you more information
See next slide for an example

Presenter Notes

Example: `factory=True`

parsing with `factory=True` automatically extracts interface values

>>> from ciscoconfparse import CiscoConfParse
>>> parse = CiscoConfParse('exampleswitch', syntax='ios', factory=True)
>>> intf = parse.find_objects('interface\sGigabitEthernet0/3$')[0]
>>> intf
<IOSIntfLine # 14 'GigabitEthernet1/3' info: '192.0.2.1/24'>
>>> intf.name
'GigabitEthernet1/3'
>>> intf.ipv4_addr
'192.0.2.1'
>>> intf.ipv4_netmask
'255.255.255.0
>>>

Presenter Notes

`factory=True`: Important caveats

Parsing with factory=True is BETA functionality
Read the source code for documentation
Only Cisco IOS, Cisco NXOS, and Cisco ASA have custom parsers
Functionality is limited and I'm slowly adding more
I might change the APIs whenever I want to
If you care about things changing, then don't use factory=True

Presenter Notes

Modify configs

[mpenning@localhost]$ python
Python 2.7.3 (default, Mar 14 2014, 11:57:14) 
[GCC 4.7.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>
>>> from ciscoconfparse import CiscoConfParse
>>> parse = CiscoConfParse('/path/to/the/config', syntax='ios')
>>>
>>> # Standardize switchport configs with 0.5% broadcast storm control
>>> parse.replace_children(r'^interface\s\S+?thernet', 
...     r'broadcast\slevel\s\S+', 'broadcast level 0.5')
...
[' storm-control broadcast level 0.5']
>>>
>>> # Now save the new version...
>>> parse.save_as('/path/to/the/newconfig')

Presenter Notes

Diff configs

>>> from ciscoconfparse import CiscoConfParse
>>> BASELINE = """!
... interface GigabitEthernet0/1
...  ip address 10.0.0.1 255.255.255.0
... !""".splitlines()
>>> REQUIRED_CONFIG = """!
... interface GigabitEthernet0/1
...  ip address 172.16.1.1 255.255.255.0
...  no ip proxy-arp
... !""".splitlines()
>>> parse = CiscoConfParse(BASELINE)
>>>
>>> # Build diffs to convert the BASELINE to the REQUIRED config
>>> print '\n'.join(parse.sync_diff(REQUIRED_CONFIG, ''))
interface GigabitEthernet0/1
 no ip address 10.0.0.1 255.255.255.0
interface GigabitEthernet0/1
 ip address 172.16.1.1 255.255.255.0
 no ip proxy-arp
>>>

Presenter Notes

Notes about diffs

The diffs use python's standard difflib
As you may have noticed, the diffs are kindof dumb... We didn't need to delete the ip address before adding another one. We did't need to configure interface GigabitEthernet0/1 twice.

Presenter Notes

Cisco Ranges

CiscoRange() can help you iterate over ranges of values

>>> from ciscoconfparse.ccp_util import CiscoRange
>>> intfs = CiscoRange('Gi1/0/1-5')
>>> for ii in intfs:
...     print ii
...
Gi1/0/1
Gi1/0/2
Gi1/0/3
Gi1/0/4
Gi1/0/5
>>> 'Gi1/0/2' in intfs
True
>>> 'Gi1/0/8' in intfs
False
>>>

Presenter Notes

DNS Lookups

Most people need DNS for their router and switch addresses
Thus, it's helpful to have DNS functionality in CiscoConfParse
DNS lookup support: Use dns_query()

Presenter Notes

DNS Query Example

>>> from ciscoconfparse.ccp_util import dns_query
>>> dns_query('www.pennington.net', 'A', '4.2.2.2')
set([<DNSResponse 'A' result_str='65.19.187.2'>])
>>> answer = dns_query('www.pennington.net', 'A', '4.2.2.2')
>>> str(answer.pop())
'65.19.187.2'
>>>

Presenter Notes

Parsing Junos

Is it possible? Yes (after Github issue #17)
Be aware that this will convert your Junos configuration to a Cisco-IOS style
See next slide for an example

Presenter Notes

Parsing Junos (example)

>>> from ciscoconfparse import CiscoConfParse
>>> parse = CiscoConfParse('configs/sample_01.junos', syntax='junos', 
...     comment='#!')
>>> print '\n'.join(parse.ioscfg[0:5])
!# Last commit: 2015-06-28 13:00:59 CST by mpenning
system
    host-name TEST01_EX
    domain-name pennington.net
    domain-search [ pennington.net lab.pennington.net ]
>>>

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Help	h

Use re_match_iter_typed() to extract values with a regex match group

parsing with factory=True automatically extracts interface values

Table of Contents

Help

Use `re_match_iter_typed()` to extract values with a regex match group

parsing with `factory=True` automatically extracts interface values