  Sentry Firewall CD HOWTO
  Stephen A. Zarkos, Obsid@Sentry.net <mailto:Obsid@Sen
  try.net>
  v1.0, 2002-03-20

  This document is designed as an introduction on how the Sentry Fire
  wall CDROM works and how to get started using the system.
  ______________________________________________________________________

  Table of Contents



  1. Introduction

     1.1 What is the Sentry Firewall CD?
     1.2 Why would I use a CD-based firewall or server?
     1.3 I'm a Linux newbie, will Sentry Firewall CD be a good choice for me?
     1.4 Minumum Requirements
     1.5 Copyrights and Disclaimer

  2. How the CD Works (Overview)

     2.1 The boot process
     2.2 ISOLINUX
     2.3 The CD Configuration scripts

  3. Obtaining the CDROM

     3.1 Downloading
     3.2 Purchasing
     3.3 Burning the CDROM

  4. Using the Sentry Firewall CDROM

     4.1 Introduction
     4.2 The sentry.conf file
        4.2.1 Example
     4.3 Network Configuration
        4.3.1 Example
     4.4 Other Useful Configuration Directives
     4.5 Putting it all together, managing multiple nodes from a single location.
     4.6 Example sentry.conf and disk images

  5. Overview of Available Configuration Directives

     5.1 Replacing rc/config files
     5.2 'device' directive support
     5.3 'nameserver' directive
     5.4 'include' directive
     5.5 Copying files (|=)
     5.6 Making Symlinks (=>)
     5.7 'cdrom' directive
     5.8 'cron' directive
     5.9 hostname

  6. Building a Custom Sentry CD

     6.1 Introduction
     6.2 The development system(How I do it)
     6.3 The RAMdisk Image
     6.4 Making the ISO Image

  7. More Information

     7.1 Mailing List
     7.2 Frequently Asked Questions
     7.3 About Sentry Network Security


  ______________________________________________________________________

  1.  Introduction

  This is the long-overdue Sentry Firewall CDROM howto.  I hope this
  document helps get you started using the Sentry Firewall CD and
  answers any questions you might have regarding how the system works.
  The most current version of this howto can be obtained at the
  following URL: <http://www.SentryFirewall.com/files/howto/>.
  If you would like to add anything to this document, or if you have any
  questions or comments please feel free to email me, Obsid@Sentry.net
  <mailto:Obsid@Sentry.net?subject=HOWTO>.



  1.1.  What is the Sentry Firewall CD?

  The Sentry Firewall CD is a Linux-based bootable CDROM suitable for
  use in a variety of different operating environments.  The system is
  designed to be configured dynamically via a floppy disk or over a
  network.  This allows one to configure the system dynamically, eventho
  much of the actual system is on read-only(CDROM) media.



  1.2.  Why would I use a CD-based firewall or server?

  There are several advantages of using a CDROM based system in various
  security related environments.  The main system is centered around the
  ramdisk; a compressed file system image which is loaded into RAM at
  boot time.  Any changes to the ramdisk image are temporary, and will
  be undone upon the next reboot. Furthermore, the ramdisk, kernel,
  binaries, etc,  related to the operating system are kept on read-only
  media(CDROM).  This means that if the security of a box running a
  CDROM based system is ever compromised the attacker can at best own
  the box until the next reboot.  So there is no real threat of having
  to go through the tedious task of rebuilding and hardening the system
  after a successful attack is discovered.



  1.3.  I'm a Linux newbie, will Sentry Firewall CD be a good choice for
  me?

  At the moment, the Sentry Firewall CD is based on a pretty generic
  Slackware Linux system.  You should probably be somewhat familiar with
  Linux and how to configure the system in order to get the most use out
  of the CD.  But, even if you are a Linux newbie, I encourage you to
  give it a shot anyway - it's free, after all.

  But, basically, there are no GUIs, no scripts to do it for you.  The
  idea behind the configuration of the CD is that you are able to
  reconfigure the system by replacing the startup scripts and the
  various system and configuration files present on the system at boot
  time.  Most of these are simply text files and shell scripts that you
  need to edit by hand in order to configure properly.  There are,
  however, usually plenty of resources available to assist you in
  configuring a specific service or daemon(HOWTOs on linux.org, for
  example).


  1.4.  Minumum Requirements


    x86 computer with CD-ROM

    BIOS that supports the eltorito standard(booting from the cdrom).

    32MB RAM(64MB or more recommended)

    Easy access to coffee/tea/soda or equivalent stimulant.

    Floppy disk drive(optional)


  1.5.  Copyrights and Disclaimer

  The current copyright and disclaimer can be found on the website;
  <http://www.SentryFirewall.com/files/COPYRIGHT>.  It applies to the
  Sentry Firewall CD, and all the scripts and documentation associated
  with it.



  2.  How the CD Works (Overview)

  This section is just an overview to explain how the Sentry Firewall CD
  works, that is, from the process of loading the kernel to running the
  Sentry Firewall CD configuration scripts located on the RAMDisk.


  2.1.  The boot process

  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(/).

  An obvious necessity for deploying CDROM based systems is the ability
  to dynamically configure the system for various environments with
  different configurations, which is what a good majority of this
  project is dedicated to building.  A simple way to do this is to give
  the user the ability to customize the startup scripts located in
  /etc/rc.d before they are actually used, as well as the ability to
  customize other important system configuration files.

  At boot time, the /etc and /etc/rc.d directories are nearly empty.  On
  a Slackware system the first rc file to run is /etc/rc.d/rc.S - and it
  is from this file where we run the configuration scripts that look for
  a configuration file(sentry.conf), and place the proper configuration
  and system files in /etc and various subdirectories under /etc.  If
  there is not a configuration directive for a specific file, or if a
  configuration file cannot be found, then the default system files are
  used - which are located in /etc/default/* on the ramdisk.



  2.2.  ISOLINUX

  Early versions of the Sentry Firewall CD utilized the 2.88MB floppy
  emulation method, along with either lilo or syslinux to boot the
  kernel and load the ramdisk.  This method proved very limiting for two
  reasons; A) the total size of the compressed ramdisk AND kernel was
  limited to 2.88MB, and B) it was quite slow compared to the current
  method.

  The Sentry Firewall CD is currently utilizing the isolinux.bin boot
  record with no emulation in order to properly boot the CDs.  This
  allows us to use a much larger ramdisk and offer a choice of several
  kernels to boot at boot time.

  More information about syslinux can be found at syslinux.zytor.com
  <http://syslinux.zytor.com/>.



  2.3.  The CD Configuration scripts

  As previously mentioned, the first rc script to run on a Slackware
  system is called /etc/rc.d/rc.S.  It is from this file where we run
  our configuration scripts, which reside in /etc/rc.d/SENTRY/ on the
  ramdisk.  The first script to run is called 'cd-config.pl', which is
  essentially the mainline for the entire program.  The other scripts
  that are used are called 'get_config.pl', for this project, and are
  essentially the mainstay of the entire configuration process.

  In depth review of these scripts is a little beyond the scope of this
  document, but is covered a bit in the file called 'DOCUMENTATION'
  available on the website ( <http://www.SentryFirewall.com/>).  The
  files are written in perl, and do several important things; read in
  and parse the configuration file(sentry.conf), locate and retrieve the
  important files detailed in the sentry.conf file, and replace the
  system default files with the ones the user has defined in the
  configuration file.



  3.  Obtaining the CDROM

  3.1.  Downloading

  The CDROM is distributed as a gzip or bzip2 compressed iso image, and
  is generally between 95-105MB in size.  Available download mirrors are
  listed on the websites,  <http://www.SentryFirewall.com/> or
  <http://Sentry.Sourceforge.net/>.


  3.2.  Purchasing

  The Sentry Firewall CD is also available for purchase over the web.
  Although the iso image is free to use and distribute, purchasing the
  CD will help support the project and help ensure continued
  development.  For more information please visit
  <http://www.SentryFirewall.com/purchase/>

  Custom versions of the CD tailored to a specific network configuration
  are also available upon request.  Please email me
  <mailto:Obsid@Sentry.net> for more information.


  3.3.  Burning the CDROM

  This section will attempt a general overview on how to burn the CD iso
  image once you have obtained it from one of the mirrors.  All the
  commands presume you're working in Linux, if not, then I'm afraid
  you're on your own.

  First, let's decompress the iso image:
  NOTE: Make sure you have enough disk space, the decompressed iso image
  can be somewhere between 250MB and 300MB.



       blah@wherever:~$ gzip -d sentrycd.iso.gz

       or

       blah@wherever:~$ bzip2 -d sentrycd.iso.bz2



  Verify the integrity of the iso image,



  blah@wherever:~$ md5sum -b sentrycd.iso



  Now, let's try to burn the CD.  You'll need the 'cdrecord' utility
  available, it can be obtained here
  <http://www.fokus.gmd.de/research/cc/glone/employees/joerg.schilling/private/cdrecord.html>.
  You will want to run 'cdrecord -scanbus' in order to find the 'dev'
  value required for the following command.  You will also need to know
  the write speed of your CDRW.  Details on how to set this all up are
  beyond the scope of this document, please refer to the CD Writing
  HOWTO <http://www.linux.org/docs/ldp/howto/CD-Writing-HOWTO.html> for
  more details.



       blah@wherever:~$ DEV="DEV_LINE_HERE" SPEED="SPEED"
       blah@wherever:~$ cdrecord -v -data speed=$SPEED dev=$DEV sentrycd.iso



  That's it, you now have a Sentry Firewall CDROM.  By the way, you may
  have to be root to do all this.

  Keep in mind, if you simply want to look at the ISO image without
  actually burning the CD, you can mount the image on a loopback device;



       blah@wherever:~$ mount -o loop ./sentrycd.iso /MOUNT_POINT



  Where "MOUNT_POINT" is where you would like the CD mounted.  You may
  then 'cd' to the MOUNT_POINT directory and poke around - don't forget
  to 'umount' the image once you're finished.  This assumes you have
  support in your kernel for the loopback device.  You probably do, but
  once again, recompiling kernels is beyond the scope of this document.



  4.  Using the Sentry Firewall CDROM

  4.1.  Introduction

  The configuration scripts which are run from /etc/rc.d/rc.S first look
  for a configuration file called 'sentry.conf' on a floppy disk which,
  if present, will be mounted on /floppy.  In order to configure the
  Linux system for use in any particular environment the user must have
  the ability to replace the system default files with his/her own
  copies.  The 'sentry.conf' file basically tells the configuration
  scripts which files it should replace and where those files are.

  A good example of a sentry.conf file can be found on the Sentry
  Firewall CD in the directory /SENTRY/scripts/cd-config/.
  Configuration floppy disk images(1.44M) can also be found in
  /SENTRY/images/ on the CD.



  4.2.  The sentry.conf file

  The main configuration file for the system is called 'sentry.conf'.
  It will first be looked for on a floppy disk(/dev/fd0).  The file
  accepts several configuration directives, many of which will be
  discussed below.


  4.2.1.  Example

  A basic configuration file looks like the following (everything after
  a '#' sign is interpreted as a comment):


  ----snip----
  ## Basic Sentry Firewall CD config file(sentry.conf)

  rc.M = /floppy/config1/rc.M
  rc.inet1 = /floppy/config1/rc.inet1

  passwd = /floppy/config1/passwd
  shadow = /floppy/config1/shadow

  # EOF #
  ----snip----



  The syntax is pretty simple, the default 'rc.M' file will be replaced
  with the user defined 'rc.M' file located in the '/floppy/config1/'
  directory.  Same goes for 'rc.inet1', 'passwd', and the 'shadow' file.
  But it is imortant to remember, the first place the sentry.conf file
  will be looked for is on /dev/fd0, which if found, will be mounted on
  /floppy.  This is why all these files appear to be located in the
  /floppy directory, it is simply the mount point for the floppy disk.

  Unfortunately, you cannot arbitrarily replace files, for example the
  following will likely not be parsed correctly:

       foo.conf = /floppy/config1/foo.conf



  The configuration scripts only recognize a certain number of
  configuration files.  There are other very easy ways to replace files
  that are not supported by default, however.  These will be discussed
  below.



  4.3.  Network Configuration

  As of version 1.0.5, a new syntax for the configuration directives are
  recognized; those with an "http://" or "ftp://" prefix.  This
  basically means that the following syntax is now supported:

       inetd.conf = ftp://user:pass@123.123.123.123/config1/inetd.conf



  In order to accomplish this the configuration scripts need to have the
  ability to set up an ethernet interface, as well as obtain nameserver
  information from the sentry.conf file.  The syntax to accomplish this
  is the following:


       device{1..10} = <device>:<driver>:<IP address>[|Gateway_IP]

       or..

       device{1..10} = <device>:<driver>:dhcp[|Hostname]



  And to set up a nameserver:


       nameserver = <IP_ADDRESS>



  So, for example to set up an interface called "eth0", which uses the
  "tulip" driver and can obtain its ip address from a DHCP server, we
  can use the following line:

       device1 = eth0:tulip:dhcp



  As you can see, a total of 10 devices are allowed.  Let's say we now
  want to set up an interface "eth1" that uses an "rtl8139" chip, and
  has a static IP(192.168.1.2) and a default gateway(192.168.1.1):

       device2 = eth1:8139too:192.168.1.2|192.168.1.1



  NOTE: It is important to keep in mind that whatever devices you set up
  during the configuration process will be promptly taken down after the
  configuration is complete.  This setup is only used so you can
  retrieve configuration files over the network, via http and ftp.  For
  more permanant network configuration, please use the rc.inet1 file.



  4.3.1.  Example


  ----snip----
  ## Basic Sentry Firewall CD config file to retrieve files via http or ftp.

  device1 = eth0:tulip:192.168.1.2|192.168.1.1
  nameserver = <MY_DNS_IP>

  rc.M = ftp://user:pass@config.sentry.net/node1/rc.M
  rc.inet1 = http://user:pass@config.sentry.net/all_nodes/rc.inet1

  passwd = http://user:pass@config.sentry.net/all_nodes/passwd
  shadow = ftp://user:pass@config.sentry.net/node1/shadow

  # EOF #
  ----snip----



  4.4.  Other Useful Configuration Directives

  Copy file /floppy/someconfig.conf to /etc/someconfig.conf -


       /floppy/someconfig.conf |= /etc/someconfig.conf

       OR, this does the same thing.

       /etc/someconfig.conf = /floppy/someconfig.conf



  Make a symlink called /etc/someconfig.conf that points to
  /etc/otherconfig.conf -



       /etc/someconfig.conf => /etc/otherconfig.conf



  The include directive.  Grabs another sentry.conf file either from
  another location -


       include = ftp://user:pass@config.sentry.net/node1/sentry.conf



  Keep in mind, however, that the include directive is one of the first
  directives to be parsed.  Any configuration directives parsed from the
  included sentry.conf file that conflict with directives in the
  previously parsed sentry.conf files will clobber the old ones.



  4.5.  Putting it all together, managing multiple nodes from a single
  location.

  In order to manage multiple nodes at a single location, you can use a
  bare sentry.conf file located on a floppy disk, and then grab files
  from your ftp or http servers.


  ----snip----
  ## Basic Sentry Firewall CD config file.

  device1 = eth0:tulip:dhcp
  nameserver = <DNS_IP>
  include = ftp://user:pass@config.sentry.net/node1/sentry.conf

  ----snip----



  The included sentry.conf file will then be parsed, and files replaced
  via http or ftp if you like.  You can now edit your sentry.conf and
  configuration files at a central location.



  4.6.  Example sentry.conf and disk images

  An example configuration disk image is available on the CDROM.  The
  disk is an ext2 formatted disk, and is located in the
  '/SENTRY/images/' directory on the CD.  There is also a very complete
  sentry.conf file on the disk which may help clarify alot of these
  directives.  Use a command like the following to create the
  configuration disk:

       blah@wherever:~$ dd if=/cdrom/SENTRY/images/ext2-144.img of=/dev/fd0
       2880+0 records in
       2880+0 records out



  5.  Overview of Available Configuration Directives

  5.1.  Replacing rc/config files

  To replace a file that is supported by the configuration scripts, you
  may use the following syntax:

       filename = /location/of/filename


  Where the location of the file is often '/floppy/filename'

  The following rc/config files are currently supported



  rc.M
  rc.netdevice
  rc.inet1
  rc.inet2
  rc.local
  rc.modules
  rc.firewall
  rc.firewall.nat
  fstab
  passwd
  shadow
  group
  shells
  profile
  resolv.conf
  hosts
  ftpusers
  hostname
  newsyslog.conf
  openssl.cnf
  syslog.conf
  syslog-ng.conf
  inetd.conf
  proftpd.conf
  squid.conf
  httpd.conf
  smb.conf
  snort.conf
  pptpd.conf
  pppoe.conf
  gated.conf
  zebra.conf
  hosts.equiv
  shosts.equiv
  ssh_config
  sshd_config
  ssh_host_key
  ssh_host_key.pub
  ssh_host_dsa_key
  ssh_host_dsa_key.pub
  ssh_host_rsa_key
  ssh_host_rsa_key.pub
  ssh_known_hosts
  ssh_known_hosts2



  To replace files not supported by the configuration scripts, use the



  5.2.

  Set up an ethernet device to use during configuration.



       device[#] = [device_name]:[driver_name]:[IP_Address]<|gateway>
       device[#] = [device_name]:[driver_name]:dhcp<|hostname>

       NOTE: 1) <hostname> and <gateway> are optional, but sometimes required.
             2) Most ethernet devices are supported.  If you find one that isn't
                and you think it should be, please let me know.
             3) "device1" to "device10" are supported.

  Examples:
       device1 = eth0:tulip:192.168.1.50|192.168.1.1
       device2 = eth1:via-rhine:dhcp



  5.3.

  Set up a nameserver to use during configuration.


       nameserver = <DNS_IP>



  5.4.

  Retrieve and parse another 'sentry.conf' file.


       include = </location/of/sentry.conf>

       Or, with network support -

       include = <ftp|http>://[<user>:<pass>@]<SERVER_IP></path/to/sentry.conf>



  5.5.  Copying files (|=)

  Copy file from one location to the other.


       Syntax: source_file |= dest_file

  Example:
       Copy file /floppy/daemon.conf to /etc/daemon.conf
       /floppy/daemon.conf |= /etc/daemon.conf



  5.6.  Making Symlinks (=>)

  Create a symlink



       Syntax: dest_file => source_file(where the symlink points to)

  Example:
       Make symlink called /etc/somefile.conf that points to /etc/otherfile.conf
       /etc/somefile.conf => /etc/otherfile.conf



  5.7.

  Defines which device the CDROM is.  Most of the time the CDROM is
  detected and mounted using the /etc/rc.d/rc.cdrom script.  But this
  makes the process less error-prone.


       Syntax: cdrom = <DEVICE>

  Example:
       cdrom = /dev/hdc



  5.8.

  Replace a user's crontab file(located in /var/spool/cron/crontabs/).


  Syntax: cron:<USERNAME> = </LOCATION/OF/CRONTAB_FILE>



  5.9.  hostname

  Defines the hostname of the local machine.  This directive can be used
  to either point to a file containing the hostname of the local
  machine, or to define the hostname itself.


       Syntax: hostname = </path/to/file>
               or
               hostname = MYHOSTNAME



  6.  Building a Custom Sentry CD

  6.1.  Introduction

  This section will attempt to describe how to create a custom Sentry
  Firewall CDROM.  Unfortunately, I do not have to time to go into every
  detail.  But at the very least I will try and provide for you an
  overview of the CD creation process.



  6.2.  The development system(How I do it)

  My development system consists of 2 separate Slackware installations.
  First, I have a very complete Slackware installation on my main hard
  drive(/dev/hda).  I then have /dev/hdb1, upon which I have another,
  bare bones, Slackware installation.  This installation generally has
  no compiling tools or X stuff.  I usually have /dev/hdb1 mounted on
  /mnt, that's not a critical element, but I thought I'd mention it
  since I will refer to /mnt alot from now on.  I then have a folder
  called /CD-FW on the /dev/hdb1 installation.  Throughout this entire
  process, the Slackware installation on /dev/hda is the live running
  system, and it is from here that I compile the needed tools, kernels,
  etc and basically run everything.

  I begin by copying nearly all the files from /mnt to /mnt/CD-FW in
  order to produce what will be the next Sentry Firewall CD.  For
  example, I have a script that does something like the following:


          ## This usually spits out alot of errors, usually crap about
          ## hard links and such, but they are all ignorable.

          cp -Rdp /mnt/bin /mnt/CD-FW/
          cp -Rdp /mnt/sbin /mnt/CD-FW/
          cp -Rdp /mnt/lib /mnt/CD-FW/
          cp -Rdp /mnt/usr/bin /mnt/CD-FW/usr/
          cp -Rdp /mnt/usr/sbin /mnt/CD-FW/usr/
          cp -Rdp /mnt/usr/local/bin /mnt/CD-FW/usr/local/
          cp -Rdp /mnt/usr/lib /mnt/CD-FW/usr/
          cp -Rdp /mnt/usr/libexec /mnt/CD-FW/usr/
          cp -Rdp /mnt/usr/share /mnt/CD-FW/usr/
          cp -Rdp /mnt/usr/man /mnt/CD-FW/usr/



  I then need to create alot of other folders and files in /mnt/CD-FW in
  order to get a fairly complete system.  Things in /mnt/CD-FW/var for
  instance will often have to be created by hand in order to avoid
  copying alot of crap I don't need.  Notice, however, that I don't copy
  any /dev files, since these files will be on the ramdisk(when I get
  around to creating it).

  Ok, so now we have /mnt/CD-FW.  To make this easy for you, this is
  essentially the exact same thing that's present on the Sentry Firewall
  CDROM.  All I did was use the 'mkisofs' utility on /mnt/CD-FW.  So the
  stuff on the CD is actually a copy of what's in the /mnt/CD-FW
  directory on my hard drive.

  Having a separate, but unused Slackware system on /dev/hdb1 makes it
  easy for me to install and upgrade packages as I need them.  For
  example, if I want to use the upgradepkg utility to upgrade a package
  I get from ftp.slackware.com, I can simply do something like the
  following:



       root@mybox:~# cp /tmp/zlib.tar.gz /mnt
       root@mybox:~# cd /mnt; chroot /mnt
       root@mybox:/# upgradepkg zlib.tar.gz; exit
       .....



  Then, all I need to do is re-run the script mentioned above, the one
  that copies all those files, to update the /mnt/CD-FW directory.
  6.3.  The RAMdisk Image

  That's all nifty, but now comes the hard part... making the ramdisk.
  If you take a look at the /isolinux directory on the CDROM, you will
  see a bunch of files, one of them is called 'initrd.img' - there are
  several others as well, such as isolinux.cfg, message.txt, and
  isolinux.bin.  These files are required by isolinux in order to work
  properly.  Take a look at those files and the documentation that comes
  with syslinux to get a better idea of what all that does.  In any
  case, the 'initrd.img' file is, in fact, the compressed ramdisk image.

  To take a look at the image, do something like the following:


       blah@wherever:~$ cp /cdrom/isolinux/initrd.img /tmp/initrd.img.gz
       blah@wherever:~$ gzip -d /tmp/initrd.img.gz
       blah@wherever:~$ mount -o loop /tmp/initrd.img /MOUNT_POINT



  In a nutshell, I use the file '/SENTRY/scripts/MK-CD/mkrootdsk.sh' to
  create the rootdisk.  Please read that file and the disclaimer before
  you decide to use it.  It runs perfectly on my system, but may not run
  well at all on yours.  It basically attempts to create a rootdisk
  image to use with the Sentry CD, but it is very long and may be
  somewhat difficult to comprehend at times.  This is what happens when
  I start a project and fail to utilize proper child safety restraints.



  6.4.  Making the ISO Image

  The next file I use is called 'mkiso.sh'.  The script generally just
  declares a few variables and runs the 'mkisofs' utility.  The command
  I normally run looks like the following:



       root@mybox:~# cd /mnt/CD-FW
       root@mybox:/mnt/CD-FW# mkisofs -o sentrycd.iso -R -V "Sentry Firewall CD [v1.2.0]" -v \
          -T -d -D -N \
          -b isolinux/isolinux.bin \
          -c isolinux/eltorito.cat \
          -no-emul-boot -boot-load-size 4 -boot-info-table \
          -A "Sentry Firewall v1.2.0 (Slackware 8.0)"
       ........



  And that's it, I burn the CD and test it.  For reference, the
  following files are available on the CDROM:

    /SENTRY/scripts/MK-CD/mkrootdsk.sh (builds the rootdisk)

    /SENTRY/scripts/MK-CD/mkiso.sh     (builds final ISO image)

    /SENTRY/scripts/MK-CD/record-cd.sh (burns the ISO to a CD)



  7.  More Information

  7.1.  Mailing List

  Thanks to SourceForge.net <http://www.SourceForge.net/>, there is a
  mailing list available for the Sentry CD.

    Subscribe <http://lists.sourceforge.net/lists/listinfo/sentry-
     users>

    Archives <http://www.geocrawler.com/redir-sf.php3?list=sentry-
     users>



  7.2.  Frequently Asked Questions

  A FAQ is currently being maintain on the Sentry Firewall website, it
  can be accessed via the following URL:
  <http://Sentry.SourceForge.net/files/FAQ>.



  7.3.  About Sentry Network Security

  Sentry Network Security is an itty bitty company that specializes in
  building and maintaining Linux based firewalls, as well as various
  other network related services.  We also offer custom Sentry Firewall
  CD solutions, to help configure and build any number of systems
  utilizing the Sentry Firewall CD.  For more information, or if you'd
  like to send me any bad jokes or poetry, please email me
  <mailto:Obsid@Sentry.net?subject=HOWTO>.



