LDMud is a virtual machine, a telnet server and a compiler for the LPC language. It is a direct descendent of the original LPMud gamedriver.
LDMud is licensed as open source but may not be used for monetary gain. All new contributions are published under the terms of the 2-clause BSD license, but as long as there are components from the original LPMud driver in the LDMud source, the condition of the original driver that it may not be used for monetary gain whatsoever stays in effect. For details see COPYRIGHT.
Note that each driver implements its own LPC dialect that may not be compatible with the others.