L7 Classification and Policing in the pfSense Platform

Helder Pereira, André Ribeiro, Paulo Carvalho


Universidade do Minho
Departamento de Informática
P-4710-057 Braga, Portugal

Tel.: +351 253 604436
Fax.: +351 253 604471
E-mail: pmc at di.uminho.pt



Resumo

The typical paradigm of identifying network traffic resorting to IP packet fields or to a set of well-known ports is highly limitative. Due to profound ongoing changes in the way applications try to hide their true nature by, for instance, using non default communication ports, a new challenge is presented to the way traffic classification and policing is accomplished. We argue and demonstrate that applicationlayer inspection is a possible and convenient approach to derive the correct application protocol. This detection and classification process is of paramount importance to allow an efficient control of traffic entering the network. Taking pfSense as a case study, we extend its current layer 3 and 4 classification scheme with layer 7 (L7) capabilities, providing  a powerful solution to control traffic based on application patterns.
Through the use of L7 containers, the user can easily create a set of rules for inspection, which will drive lower-level traffic control. In addition, we propose and implement a mechanism to create automatically useful application inspection scenarios.differentiating incoming service calls.

CRC'2009, Oeiras Oct. 2010.