Sentry Firewall CD-ROM is a Linux-based bootable CDROM suitable for use as an
inexpensive and easy to maintain firewall, server, or IDS(Intrusion Detection System) Node.
The system is designed to be immediately configurable for a variety of different operating
environments via a configuration file located on a floppy disk, a local hard drive, and/or
a network via HTTP(S), FTP, SFTP, or SCP.
The Sentry Firewall CD is a complete Linux system that runs off of an initial ramdisk,
much like a floppy-based system, and a CD. The default kernel is a current 2.4.x series
kernel with various Netfilter patches applied. An OpenWall-patched current 2.2.x kernel is also available on the CD.
Booting from the CDROM is a fairly familiar process. The BIOS execs the
bootloader(Syslinux) - which then
displays a bootprompt and loads the kernel and ramdisk into memory. Once the kernel
is running, the ramdisk is then mounted as root(/). At this point our configuration
scripts are run(written in perl) that configure the rest of the system. It is the job of
these configure scripts to put the various startup and system files into the proper location
using either what is declared in the configuration file(sentry.conf) or the system defaults
located in the /etc/default directory.
Most of the critical files used at boot time can be replaced with your own copy when declared
in the configuration file. This is essentially how we allow the user to configure the system
using his/her own configuration and init files.
All of the binaries, files, scripts, etc, used to create the CD-ROM are also available
on the CD-ROM. So, with a little practice, you can easily build and customize your own
bootable Sentry Firewall CD. Please see the HOWTO for more details.
Here is a short list of some of the packages contained on the CD-ROM -
NOTE: Version numbers reflect most recent release(stable or devel).
- Current Linux Kernel: 2.4.28-ow1