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CiscoConfParse Tutorial

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

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

Example: Find interfaces

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

!python
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'>

Example: Use object properties

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

!python
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)>

Example: Use object properties

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

!python
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

Example: Find shutdown interfaces

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

!python
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

Example: Extract an interface address

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

!python
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

Using factory=True

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

Example: factory=True

parsing with factory=True automatically extracts interface values

!python
>>> 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
>>>

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

Modify configs

!python
[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')

Diff configs

!python
>>> 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
>>>

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.

Cisco Ranges

CiscoRange() can help you iterate over ranges of values

!python
>>> 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
>>>

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()

DNS Query Example

!python
>>> 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'
>>>

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

Parsing Junos (example)

!python
>>> 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 ]
>>>