PySubnetTree - A Python Module for CIDR Lookups.

The PySubnetTree package provides a Python data structure SubnetTree which maps subnets given in CIDR notation to Python objects. Lookups are performed by longest-prefix matching.

Simple example which associates CIDR prefixes with strings:

>>> import SubnetTree
>>> t = SubnetTree.SubnetTree()
>>> t["10.1.0.0/16"] = "Network 1"
>>> t["10.1.42.0/24"] = "Network 1, Subnet 42"
>>> t["10.2.0.0/16"] = "Network 2"
>>> print t["10.1.42.1"]
Network 1, Subnet 42
>>> print t["10.1.43.1"]
Network 1
>>> print "10.1.42.1" in t
True
>>> print "10.1.43.1" in t
True
>>> print "10.20.1.1" in t
False
>>> print t["10.20.1.1"]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "SubnetTree.py", line 67, in __getitem__
    def __getitem__(*args): return _SubnetTree.SubnetTree___getitem__(*args)
KeyError: '10.20.1.1'

CIDR prefixes are given as strings. Single addresses can alternatively also be passed in as integers as, e.g., returned by socket.inet_aton.

A SubnetTree also provides methods insert(prefix,object=None) for insertion of prefixes (object can be skipped to use the tree like a set), and remove(prefix) for removing entries (remove performs an exact match rather than longest-prefix).

Internally, the CIDR prefixes of a SubnetTree are managed by a Patricia tree data structure and lookups are therefore efficient even for large number of prefixes.

PySubnetTree comes with BSD license.

Download pysubnettree-0.12.tar.gz.

This packages requires Python 2.4 or newer.

Installation is pretty simple:

> python setup.py install