The support on cluster environments of "legacy protocols" is important to avoid rewriting the code of applications, but this support should not prevent to achieve the maximum communication performance. This paper addresses this issue by implementing the Berkeley sockets interface over the MMP message passing protocol, which is the lower layer of the Maestro2 cluster communication network. Experimental results show that MMP-Sockets offers a minimum latency of 25?s and a maximum throughput of 1250Mbps. These values correspond to a relative increase of 80% for the latency and a decrease of about 30% for the throughput, regarding to a communication based only on MMP. However, MMP-Sockets increases the compatibility and portability of developed applications.