Hot Copy creates an instant point-in-time snapshot of any block device while the system is running without interrupting applications or requiring the use of LVM. As block level changes are made to the real device, hot copy makes a backup copy of the changed block. The changed blocks are efficiently stored in unused space on your hard disk. These stored changed blocks maintain a point-in-time snapshot and space is only needed when you make changes to the real device. You can even write to your snapshots.
ctunnel is a program for tunneling and proxying TCP or UDP connections via a cryptographic tunnel. ctunnel can be used to secure any existing TCP or UDP based protocol, such as HTTP, Telnet, FTP, RSH, MySQL, VNC, DNS, XDMCP, NFS, etc. You can also chain or bounce connections to any number of intermediary hosts.
ipt_pkd is an iptables extension implementing port knock detection with SPA (single packet authorization). This project provides 3 parts: the kernel module ipt_pkd, the iptables user space module libipt_pkd.so, and a user space client knock program. For the knock packet, it uses a UDP packet sent to a random port that contains a SHA-256 of a timestamp, small header, random bytes, and a shared key. ipt_pkd checks the time window of the packet and does the SHA-256 to verify the packet. The shared key is never sent.
Raven's System Stats allows users to collect detailed information about an operating system, including kernel architecture, distro, operating system, kernel version, glibc version, name of login shell, number of CPUs, CPU description, hyperthreading support, CPU MHz, CPU cache, bogomips, used and total RAM, used and total swap, filesystem size and type, uptime, unique users logged in, total login shells, currently running processes, total processes since bootup, load average, X resolution, and the number of X servers running.
Grml is a live system (live CD) based on Debian. It includes a collection of GNU/Linux software especially for system administrators and users of texttools. It provides automatic hardware detection and its default shell is the zsh. You can use it e.g. as a rescue system, for analyzing systems/networks, or as a working environment. It is not necessary to install anything to a hard disk; you don't even need a hard disk to run it. Due to on-the-fly decompression, it includes more than 2 GB of software and documentation on the CD.