Security in MPSoC is gaining an increasing attention since several years. Digital convergence is one of the numerous reasons explaining such a focus on embedded systems as much sensitive and secret data are now stored, manipulated and exchanged in these systems. Most solutions are currently built at the software level; we believe hardware enhancements also play a major role in system protection. One strategic point is the communication layer as all data goes through it. Monitoring and controlling communications enable to fend off attacks before system corruption. In this work, we propose an efficient solution with several hardware enhancements to secure data exchanges in a bus-based MPSoC. Our approach relies on low complexity distributed firewalls connected to all critical IPs of the system. Designers can deploy different security policies (access right, data format, authentication, confidentiality) in order to protect the system in a flexible way. To illustrate the benefit of such a solution, implementations are discussed for different MPSoCs implemented on Xilinx Virtex-6 FPGAs. Results demonstrate a reduction up to 33% in terms of latency overhead compared to existing efforts.