root/psad/tags/psad-2.1.2/Unix-Syslog/README

       Unix::Syslog -- Perl interface to the UNIX system logger
       ========================================================

Copyright (C) 1999,2000,2001,2002 Marcus Harnisch

Introduction
============

This Module provides access to the system logger available on most
UNIX system via Perl's XSUBs (Perl's C interface).

I wrote this module because of some features I missed in Sys::Syslog
(see FAQ below) and also to do my first steps into the secrets of
Perl's XSUBs.

Copyright and distribution
==========================

This program is free software; you can redistribute it and/or modify
it under the terms of the Artistic License. A copy of the license (see
file Artistic in this directory) must be included in the package.

Installation
============

Unix::Syslog is a Perl module that makes use of XSUBs and hence
requires a working C compiler and library. Execute the following
commands to install this package (`make test' prints the results of a
test suite. Execute `make install' only if the required tests finished
successfully or if you know what you are doing):

perl Makefile.PL
make test
make install

Notes about the test suite
==========================

Some of the tests may fail because the respective constants are not
available on certain systems. You should be able to distinguish these
tests from those that fail because of a malfunction by carefully
reading the output of the test routines.

The tests that write messages to syslog cannot return a success status
since the underlying libc functions don't return appropriate
information. To verify that these tests work correctly, you should
configure syslogd so that the facility `local7' and priority `info'
will be written to a file.

OS dependent behaviour and portability
======================================

This package uses system specific functions. Programs that uses this
package may not be portable in any case. If you plan to write portable
code using this package, please consult the manuals of the systems you
wish to run the software on. Then modify your program accordingly.

As of version 0.99 Unix::Syslog provides two functions priorityname()
and facilityname() that return the names of priority and facility,
respectively. This functionality is only enabled if an according
`#define' is enabled through Makefile.PL. By default this statement is
commented out.

Known bugs
==========

OS      Description                                Workaround
---------------------------------------------------------------------------
Linux   On systems using glibc2 (<= version 2.1),  None possible.
        setting the log mask has no effect.

Frequently Asked Questions
==========================

1.  What is the benefit of using this module instead of Sys::Syslog?

    Sys::Syslog always opens a network connection to the syslog
    service. At least on Linux systems this may lead to some
    trouble, because

    o   Linux syslogd (from package sysklogd) does not listen to the
        network by default. Most people working on stand-alone
        machines (including me) didn't see any reason why to
        enable this option. Others didn't enable it for security
        reasons.

        OS-independent, some sysadmins may run a firewall on
        their network that blocks connections to port 514/udp.

    o   By default Linux syslogd doesn't forward messages which have
        already already received from the network to other log
        hosts. There are reasons not to enable this option
        unless it is really necessary. Looping messages
        resulting from a misconfiguration may break down your
        (log-)system.

    Peter Stamfest <peter.stamfest@eunet.at> pointed out some
    other advantages of Unix::Syslog, I didn't came across my
    self.

    o   LOG_PERROR works.

    o   works with perl -Tw without warnings and problems due to
        tainted data as it is the case for Sys::Syslog in some
        special applications. [Especially when running a script
        as root]

2.  Well, is there any reason to use Sys::Syslog any longer?

    Yes! In contrary to Unix::Syslog, Sys::Syslog works even if
    you don't have a syslog daemon running on your system as
    long as you are connected to a log host via a network and
    have access to the syslog.h header file of your log host to
    generate the initial files for Sys::Syslog (see
    Sys::Syslog(3) for details). Unix::Syslog only logs to your
    local syslog daemon which in turn may be configured to
    distribute the message over the network.

3.  Are calls to the functions provided by Unix::Syslog compatible
    to those of Sys::Syslog?

    Currently not. Sys::Syslog requires strings to specify many
    of the arguments to the functions, while Unix::Syslog uses
    numeric constants accessed via macros as defined in
    syslog.h. Although the strings used by Sys::Syslog are also
    defined in syslog.h, it seems that most people got used to
    the numeric arguments. I will implement the string based
    calls if there are enough people ($min_people > 10**40)
    complaining about the lack of compatibility.

Comments, Bug reports and Suggestions
=====================================

Please direct anything you wish to tell me about this package to the
address given below.

Have fun,
     Marcus Harnisch <marcus.harnisch@gmx.net>