nbdkit is a toolkit for creating NBD servers.
The key features are:
* Multithreaded NBD server written in C with good performance.
* Minimal dependencies for the basic server.
* Liberal license (BSD) allows nbdkit to be linked to proprietary
libraries or included in proprietary code.
* Well-documented, simple plugin API with a stable ABI guarantee.
Lets you export unconventional block devices easily.
* You can write plugins in C, Go, Lua, Perl, Python, OCaml, Ruby,
Rust, shell script or Tcl.
* Filters can be stacked in front of plugins to transform the output.