ciscoconfparse2 is similar to an advanced grep and diff API for python; it should be used with text network configuration files (such as those from Arista, Cisco, Juniper, Palo Alto, etc). It is the next generation of ciscoconfparse, which was the primary development vehicle from 2007 until 2023.

ciscoconfparse2 can:

  • Audit existing router / switch / firewall / wlc configurations against a text configuration template

  • Retrieve portions of the configuration

  • Modify existing configurations

  • Build new configurations

The library examines a Cisco or JunOS-style configuration and breaks it into a set of linked parent / child relationships; each configuration line is stored in a different IOSCfgLine object.

ciscoconfparse2 overview

Figure 1. An Example of Parent-line / Child-line relationships

Then you issue queries against these relationships using a familiar family syntax model. Queries can either be in the form of a simple string, or you can use regular expressions. The API provides powerful query tools, including the ability to find all parents that have or do not have children matching a certain template.

The package also provides a set of methods to query and manipulate the IOSCfgLine objects themselves. This gives you a flexible mechanism to build your own custom queries, because the IOSCfgLine objects store all the parent / child hierarchy in them.

What’s new in ciscoconfparse2

I wrote the original ciscoconfparse in 2007 as literally my first Python project.

After many years of updates, ciscoconfparse grew too large. ciscoconfparse2:

  • Is tested against Python3.9+ (limited to Python 3.9+ due to python type annotation dynamics before 3.9)

  • Includes a CLI tool to grep / search for a variety of things from the CLI

  • Streamlines the API on a simpler user interface.

  • Removes legacy and flawed methods from the original (this could be a breaking change for old scripts).

  • Defaults ignore_blank_lines=False (this could be a breaking change for old scripts).

  • Adds the concept of change commits; this is a config-modification safety feature that ciscoconfparse lacks

  • Is better at handling multiple-child-level configurations (such as IOS XR and JunOS)

  • Can search for parents and children using an arbitrary-length list of ancestors

  • Adds an auto_commit keyword, which defaults True; however, many loading thousands of configuration lines could be slow with auto_commit=True.

  • Brings vast improvements to Cisco IOS diffs

  • Intentionally requires a different import statement to minimize confusion between them

As such, ciscoconfparse2 API is not the same; it uses different syntax than the original ciscoconfparse. However, the new syntax is less magical, and more pythonic.

The biggest difference in the two APIs is the multi-level search capability. To illustrate, assume we parse this fake multi-level configuration of interface features:

interface Ethernet0/0
interface Ethernet0/1
interface Serial1/0

The original ciscoconfparse could not find parameter01 on Ethernet0/1 without iterating in a loop (because two different interfaces have parameter01). However, ciscoconfparse2 can easily identify it by searching a list of elements with find_child_objects():

>>> from ciscoconfparse2 import CiscoConfParse
>>> # Assume we parsed the config into 'parse'
>>> parse
<CiscoConfParse: 9 lines / syntax: ios / comment delimiters: ['!'] / auto_indent_width: 1 / factory: False / ignore_blank_lines: False / encoding: 'UTF-8' / auto_commit: True>
>>> # Expect to see a list with single child here...
>>> parse.find_child_objects(["Ethernet", "feature01", "parameter"])
[<IOSCfgLine # 5 '  parameter01' (parent is # 4)>]

However, you can still get multiple children by using a less-specific regex:

>>> # Expect to see a list of two children here... search across
>>> # any Ethernet feature
>>> parse.find_child_objects(["Ethernet", "feature", "parameter"])
[<IOSCfgLine # 2 '  parameter01' (parent is # 1)>, <IOSCfgLine # 5 '  parameter01' (parent is # 4)>]

Finally, you can still get parent objects with find_parent_objects():

>>> parse.find_parent_objects(["Ethernet", "feature01", "parameter"])
[<IOSCfgLine # 3 'interface Ethernet0/1'>]

What is ciscoconfparse2 good for?

After several network evolutions, you may have a tangled mess of conflicting or misconfigured network devices. Misconfigurations of proxy-arp, static routes, FHRP timers, routing protocols, duplicated subnets, cdp, console passwords, or aaa schemes have a measurable affect on up time and beg for a tool to audit them. However, manually scrubbing configurations is a long and error-prone process.

Audits aren’t the only use for ciscoconfparse2. Let’s suppose you are working on a design and need a list of dot1q trunks on a switch with more than 400 interfaces. You can’t grep for them because you need the interface names of layer2 trunks; the interface name is stored on one line, and the trunk configuration is stored somewhere below the interface name. With ciscoconfparse, it’s really this easy…

>>> from ciscoconfparse2 import CiscoConfParse
>>> parse = CiscoConfParse('/tftpboot/largeConfig.conf', syntax='ios', factory=False)
>>> # Find parent interfaces that are configured with 'switchport trunk'
>>> dot1q_trunks = parse.find_parent_objects(["^interface", "switchport trunk"])
>>> for intf in dot1q_trunks:
...     print(intf)
<IOSCfgLine # 217 'interface GigabitEthernet1/1'>
<IOSCfgLine # 237 'interface GigabitEthernet1/2'>

This example:

  • Imports ciscoconfparse2

  • Searches a Cisco IOS configuration file stored in /tftpboot/largeConfig.conf

    • Use the default ‘ios’ syntax for the configuration file

    • Use the default ‘factory’ setting, which is disabled

  • Search for configuration lines which have:

    • The parent beginning with interface (and anything else on the config line); ^ is a special character that requests to anchor the string at the beginning of the config line.

    • A child of that parent configured with switchport trunk (and anything else on the config line)

The search found two configuration lines.

We don’t have Ciscos

Don’t let that stop you. CiscoConfParse parses anything that has a Cisco IOS style of configuration, which includes:

  • Cisco IOS, Cisco Nexus, Cisco IOS-XR, Cisco IOS-XE, Aironet OS, Cisco ASA, Cisco CatOS

  • Arista EOS

  • Brocade

  • HP Switches

  • Force 10 Switches

  • Dell PowerConnect Switches

  • Extreme Networks

  • Enterasys

You can also parse brace-delimited configurations into a Cisco IOS style, which means that CiscoConfParse understands these configurations too:

  • Juniper Networks Junos, and Screenos

  • Palo Alto Networks Firewall configurations

  • F5 Networks configurations