From Vertubleu

nuttcp - network performance measurements

nuttcp is an easy TCP/UDP network testing tool.

It permits measuring network throughput between 2 peers running nuttcp. It is available as a package in Ubuntu (apt-get install nuttcp), or compiled from the source provided here: http://wcisd.hpc.mil/nuttcp/Nuttcp-HOWTO.html

(I tested version 5.5.5)

Some sample command lines:

nuttcp -R10m IP@

nuttcp -i1 -w100g IP@