GNU Mach is the microkernel upon which a GNU Hurd system is based. It provides an Inter Process Communication (IPC) mechanism which the Hurd uses to define interfaces for implementing in a distributed multi-server fashion the services a traditional operating system kernel provides. Mach is particularly well-suited for SMP and network cluster techniques. Thread support is provided at the kernel level, and the kernel itself takes advantage of that. Network transparency at the IPC level makes resources of the system available across machine boundaries.
The GNU Hurd is the GNU project's replacement for the Unix kernel. The Hurd is a collection of servers that run on the Mach microkernel to implement file systems, network protocols, file access control, and other features that are implemented by the Unix kernel or similar kernels (such as Linux).
Libchop is a set of utilities and library for data backup and distributed storage. Its main application is chop-backup, an encrypted backup program that supports data integrity checks, versioning at little cost, distribution among several sites, selective sharing of stored data, adaptive compression, and more. The library itself, which chop-backup builds upon, implements storage techniques such as content-based addressing, content hash keys, Merkle trees, similarity detection, and lossless compression. It makes it easy to combine them in different ways. The ‘chop-archiver’ and ‘chop-block-server’ tools, illustrated in the manual, provide direct access to these facilities from the command line. It is written in C and has Guile (Scheme) bindings.
fakechroot provides a fake chroot environment to programs. A fake chroot allows you to run programs which require root privileges on an unprivileged user account. For example, you can create a Debian bootstrap or a development environment and build packages inside a chroot'ed system using a standard non-root user account. You can then use the apt-get command to install other packages without root privileges.