Python Radius is a pure python 2.7.x radius client which supports two important extension RFCs:

The Message-Authenticator extension - authenticating a radius packet using an MD5 HMAC

and

Use of Status-Server Packets in the Remote Authentication Dial In User Service (RADIUS) Protocol - checking a radius server is alive without generating spurious log entries.

import radius

with radius.connect(('10.0.0.1', 1812), 'secret') as connection:
    print connection.ping()
    print connection.authenticate('username', 'password')