PyGSSAPI

PyGSSAPI provides both low-level and high level wrappers around the GSSAPI C libraries. While it focuses on the Kerberos mechanism, it should also be useable with other GSSAPI mechanisms that do not rely on mechanism-specific C values that cannot easily be translated into Python.

Requirements

• A working implementation of GSSAPI (such as from MIT Kerberos) which includes header files
• a C compiler (such as GCC)
• Cython (NEW, to compile from scratch)
• the flufl.enum Python package
• the nose package (for tests)
• the shouldbe package (for tests)

Installation

Easy Way

$ pip install pygssapi

From the Git Repo

$ git clone https://github.com/DirectXMan12/python-gssapi.git
$ python setup.py build
$ python setup.py install

Tests

I have written some tests of PyGSSAPI; they live in the gssapi.tests directory. Currently the basic gssapi.base commands and gssapi.client.BasicGSSClient have been tested. Before running the tests, a valid 'host/[FQDN]' (e.g. 'host/some.domain') must have been kinit-ed. If you run tox, it will do this for you (you will likely need to run tox with sudo).

$ sudo tox

or

$ sudo kinit host/some.domain -k
$ sudo setup.py nosetests

Structure

PyGSSAPI is composed of two parts: the low-level, C-style wrapper and the high-level, Python-style wrapper (which is a wrapper around the low-level API). Modules written in C are denoted by '(C)', whereas those written in Python are denoted '(Py)'

Low-Level API

The low-level API lives in gssapi.base. The methods contained therein are designed to match closely with the original GSSAPI C methods. They follow the given format:

• Names are camelCased versions of the C method names, with the gssapi_ prefix removed
• Parameters which use C int constants as enums have flufl.enum.IntEnum classes defined, and thus may be passed either the enum members or integers
• In cases where a specific constant is passed in the C API to represent a default value, None should be passed instead
• In cases where non-integer C constants are passed, flufl.enum.Enum classes are defined for common values
• Major and minor error codes are returned via gssapi.base.GSSError
• All other relevant output values are returned in a tuple in the return value of the method (in cases where a non-error major status code may be returned, an additional member of the tuple is provided)

Structure

gssapi : /

base : /

includes all sub-packages automatically

impl : (C)

core C-API methods

status_utils : (C)

utilities for dealing with status codes

types : (Py)

Enumerations and Exception Types

Examples

import gssapi.base as gb

TODO(sross): provide more examples

High-Level API

The high-level API lives directly under gssapi. The classes contained in each file are designed to provide a more Python, Object-Oriented view of GSSAPI. Currently, they are designed for the basic GSSAPI tasks, but will be expanded upon in the future.

Structure

gssapi : /

client : (Py)

basic clients

BasicGSSClient

a client capable of performing basic GSS negotiation/encryption

BasicSASLGSSClient

a helper class to simplify working with SASL GSSAPI

type_wrappers : (Py)

provides useful wrappers around some Python capsule objects

Examples

import gssapi.client as gss

client = gss.BasicGSSClient('vnc@some.host', security_type='encrypted')

init_token = client.setupBaseSecurityContext()
# send to server, get response back...
next_token = client.updateSecurityContext(server_resp)
# encrypt a message
msg_enc = client.encrypt('WARNING: this is secret')
# send the message, get response back...
msg_unenc = client.decrypt(server_encrypted_message)

# freeing of resources (such as deleting the security context and releasing
# the names) is handled automatically