Ksplice is practical technology for updating the Linux kernel without rebooting. It enables you to avoid the disruptive process of rebooting for kernel security updates and bugfixes. By making it easy to keep your systems up to date, Ksplice helps you avoid the security and stability risks of running out-of-date software.
LOMAC uses Low Water-Mark Mandatory Access Control to protect the integrity of processes and data from viruses, trojan horses, malicious remote users, and compromised network server daemons. The LOMAC loadable kernel module can be used to harden Linux systems without any changes to existing kernels, applications, or configuration files. Due to its simplicity, LOMAC itself requires no configuration, regardless of the users and applications present on the system. Although some features and fixes remain to be implemented, LOMAC presently provides sufficient protection to thwart some attacks, and is stable enough for everyday use.
LUFS is a hybrid userspace filesystem framework supporting many "exotic" filesystems (localfs, sshfs, ftpfs, httpfs, socketfs, freenetfs, and nutellafs) transparently for any application. It can be regarded as doing the same job as the VFS (virtual filesystem switch) in the kernel: it is a switch, distributing the filesystem calls to its supported filesystems. However, LUFS filesystems are implemented in userspace. This would be a drawback for local filesystems where the access speed is important, but proves to be a huge advantage for networked filesystems where the userland flexibility is most important.
L7-filter is a packet classifier for Netfilter that identifies packets based on application layer (OSI layer 7) data. This means that it is able to classify packets as HTTP, FTP, Gnucleus, Kazaa, etc., regardless of ports. It complements existing matches that classify based on port numbers, packet length, TOS bits, and so on. Combined with Linux QoS, it allows for full layer 7 packet shaping.
Linice is a source-level kernel debugger for x86 systems with the look and feel of SoftIce for MS Windows. It is designed for people who are already familiar with SoftIce, but anyone can quickly get used to it. It can break into a running kernel at any time using a hotkey and supports breakpoints and single step on modules, the kernel, or user programs. It supports the VGA frame buffer, the X Window System, serial connections, and monochrome adapters.
Linux is a clone of the Unix kernel, written from scratch by Linus Torvalds with assistance from a loosely-knit team of hackers across the Net. It aims towards POSIX and Single UNIX Specification compliance. It has all the features you would expect in a modern fully-fledged Unix kernel, including true multitasking, virtual memory, shared libraries, demand loading, shared copy-on-write executables, proper memory management, and TCP/IP networking.