Re: Linux Firewall

On Fri, 26 May 2006, in the Usenet newsgroup comp.os.linux.security, in article
<slrne7envm.h8o.dozzie@xxxxxxxxxxxxxxxxxxxx>, Stachu 'Dozzie' K. wrote:

On 26.05.2006, Moe Trin <ibuprofin@xxxxxxxxxxxxxxxxxxxxxx> wrote:

Using BSD style or SysV?

Neither. Slackware's initscripts are not BSD-style for a long, long
time. It _was_ BSD-like many years ago.

Slack 9.1? From late 2003? While the package name is "sysvinit",
such files as rc.S, rc.M, rc.K, are not quite what other are using.

Some may contest that this isn't BSD, but is more like Sys3 - I won't
quibble. The main difference is that it uses comparatively few boot
scripts, and doesn't use a run-level directories. Those scripts that
it does run are explicitly called in one of the main scripts, such as
rc.S or rc.M, and adding services that run from independent scripts such
as rc.firewall means editing one of the main scripts, and inserting a
call therein.

The more common style uses a run-level directory structure. The system
initially runs something like /etc/rc.d/rc.sysinit which does the crude
basics (file system checks, mounting file systems, setting hostname and
date). Then, the system runs a second scripts like /etc/rc.d/rc which
runs the "scripts" in the run-level directories - first the K* "scripts"
to stop services not needed at "this" run-level, then the S* "scripts"
to start services that are needed at "this" run-level. These K* and S*
"scripts" are run in the same order you would see if you ran 'ls -1' in
the run-level directory. The "scripts" are normally links to the actual
script located elsewhere. Adding services in this style means adding
the real script somewhere (perhaps /etc/rc.d/init.d/ or similar), and
creating the appropriate soft links in the run-level directory.

These scripts - or even the style of the scripts - is NOT standardized.
The latest Filesystem Hierarchy Standard (http://www.pathname.com/fhs/
v2.3 was announced January 29, 2004) makes absolutely NO mention of the
scripts, and says only:

The /etc hierarchy contains configuration files. A "configuration file" is a
local file used to control the operation of a program; it must be static and
cannot be an executable binary. [4]

and that note [4] reads

[4] The setup of command scripts invoked at boot time may resemble System V,
BSD or other models. Further specification in this area may be added to a
future version of this standard.

The simple solution if you are interested in the set down and read /etc/inittab
and see what init is going to do. The man page for inittab(5) helps here. I
actually recommend this if you are interested in learning shell scripting, as
the scripts are usually written by someone who knows scripting very well, and
is _flaunting_ their skills. Reading the scripts along with the shell man page
(and perhaps the grendel's fabulous "Advanced Bash Scripting Guide" from the
LDP http://tldp.org/guides.html) is an education.

Old guy
.

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