forked from extern/shorewall_code
2024554eec
git-svn-id: https://shorewall.svn.sourceforge.net/svnroot/shorewall/trunk@399 fbd18981-670d-0410-9b5c-8dc0c1a9a2bb
157 lines
7.0 KiB
HTML
157 lines
7.0 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
|
|
<html>
|
|
<head>
|
|
<title>Shorewall Logging</title>
|
|
|
|
<meta http-equiv="content-type"
|
|
content="text/html; charset=ISO-8859-1">
|
|
|
|
<meta name="author" content="Tom Eastep">
|
|
</head>
|
|
<body>
|
|
|
|
<table border="0" cellpadding="0" cellspacing="0"
|
|
style="border-collapse: collapse;" bordercolor="#111111" width="100%"
|
|
id="AutoNumber1" bgcolor="#400169" height="90">
|
|
<tbody>
|
|
<tr>
|
|
<td width="100%">
|
|
|
|
|
|
<h1 align="center"><font color="#ffffff">Logging</font></h1>
|
|
</td>
|
|
</tr>
|
|
|
|
</tbody>
|
|
</table>
|
|
<br>
|
|
By default, Shorewall directs NetFilter to log using syslog (8). Syslog
|
|
classifies log messages by a <i>facility</i> and a <i>priority</i> (using
|
|
the notation <i>facility.priority</i>). <br>
|
|
<br>
|
|
The facilities defined by syslog are <i>auth, authpriv, cron, daemon,
|
|
kern, lpr, mail, mark, news, syslog, user, uucp</i> and <i>local0</i> through
|
|
<i>local7</i>.<br>
|
|
<br>
|
|
Throughout the Shorewall documentation, I will use the term <i>level</i>
|
|
rather than <i>priority</i> since <i>level</i> is the term used by NetFilter.
|
|
The syslog documentation uses the term <i>priority</i>.<br>
|
|
|
|
<h3>Syslog Levels<br>
|
|
</h3>
|
|
Syslog levels are a method of describing to syslog (8) the importance
|
|
of a message and a number of Shorewall parameters have a syslog level
|
|
as their value.<br>
|
|
<br>
|
|
Valid levels are:<br>
|
|
<br>
|
|
7
|
|
debug<br>
|
|
6
|
|
info<br>
|
|
5
|
|
notice<br>
|
|
4
|
|
warning<br>
|
|
3
|
|
err<br>
|
|
2
|
|
crit<br>
|
|
1
|
|
alert<br>
|
|
0
|
|
emerg<br>
|
|
<br>
|
|
For most Shorewall logging, a level of 6 (info) is appropriate.
|
|
Shorewall log messages are generated by NetFilter and are logged using
|
|
the <i>kern</i> facility and the level that you specify. If you are unsure
|
|
of the level to choose, 6 (info) is a safe bet. You may specify levels
|
|
by name or by number.<br>
|
|
<br>
|
|
Syslogd writes log messages to files (typically in /var/log/*) based
|
|
on their facility and level. The mapping of these facility/level pairs
|
|
to log files is done in /etc/syslog.conf (5). If you make changes to this
|
|
file, you must restart syslogd before the changes can take effect.<br>
|
|
|
|
<h3>Configuring a Separate Log for Shorewall Messages</h3>
|
|
There are a couple of limitations to syslogd-based logging:<br>
|
|
|
|
<ol>
|
|
<li>If you give, for example, kern.info it's own log destination then
|
|
that destination will also receive all kernel messages of levels 5 (notice)
|
|
through 0 (emerg).</li>
|
|
<li>All kernel.info messages will go to that destination and not just
|
|
those from NetFilter.<br>
|
|
</li>
|
|
|
|
</ol>
|
|
Beginning with Shorewall version 1.3.12, if your kernel has ULOG
|
|
target support (and most vendor-supplied kernels do), you may also specify
|
|
a log level of ULOG (must be all caps). When ULOG is used, Shorewall will
|
|
direct netfilter to log the related messages via the ULOG target which will
|
|
send them to a process called 'ulogd'. The ulogd program is available from
|
|
http://www.gnumonks.org/projects/ulogd and can be configured to log all
|
|
Shorewall message to their own log file.<br>
|
|
<br>
|
|
<b>Note: </b>The ULOG logging mechanism is <u>completely separate</u> from
|
|
syslog. Once you switch to ULOG, the settings in /etc/syslog.conf have absolutely
|
|
no effect on your Shorewall logging (except for Shorewall status messages
|
|
which still go to syslog).<br>
|
|
<br>
|
|
You will need to have the kernel source available to compile ulogd.<br>
|
|
<br>
|
|
Download the ulod tar file and:<br>
|
|
|
|
<ol>
|
|
<li>Be sure that /usr/src/linux is linked to your kernel source tree<br>
|
|
</li>
|
|
<li>cd /usr/local/src (or wherever you do your builds)</li>
|
|
<li>tar -zxf <i>source-tarball-that-you-downloaded</i></li>
|
|
<li>cd ulogd-<i>version</i><br>
|
|
</li>
|
|
<li>./configure</li>
|
|
<li>make</li>
|
|
<li>make install<br>
|
|
</li>
|
|
|
|
</ol>
|
|
If you are like me and don't have a development environment on your firewall,
|
|
you can do the first six steps on another system then either NFS mount
|
|
your /usr/local/src directory or tar up the /usr/local/src/ulogd-<i>version</i>
|
|
directory and move it to your firewall system.<br>
|
|
<br>
|
|
Now on the firewall system, edit /usr/local/etc/ulogd.conf and set:<br>
|
|
|
|
<ol>
|
|
<li>syslogfile <i><file that you wish to log to></i></li>
|
|
<li>syslogsync 1</li>
|
|
|
|
</ol>
|
|
I also copied the file /usr/local/src/ulogd-<i>version</i>/ulogd.init
|
|
to /etc/init.d/ulogd. I had to edit the line that read "daemon /usr/local/sbin/ulogd"
|
|
to read daemon /usr/local/sbin/ulogd -d". On a RedHat system, a simple
|
|
"chkconfig --level 3 ulogd on" starts ulogd during boot up. Your init system
|
|
may need something else done to activate the script.<br>
|
|
<br>
|
|
You will need to change all instances of log levels (usually 'info') in
|
|
your configuration files to 'ULOG' - this includes entries in the policy,
|
|
rules and shorewall.conf files. Here's what I have:<br>
|
|
|
|
<pre> [root@gateway shorewall]# grep ULOG *<br> policy:loc fw REJECT ULOG<br> policy:net all DROP ULOG 10/sec:40<br> policy:all all REJECT ULOG<br> rules:REJECT:ULOG loc net tcp 6667<br> shorewall.conf:TCP_FLAGS_LOG_LEVEL=ULOG<br> shorewall.conf:RFC1918_LOG_LEVEL=ULOG<br> [root@gateway shorewall]#<br></pre>
|
|
Finally edit /etc/shorewall/shorewall.conf and set LOGFILE=<i><file
|
|
that you wish to log to></i>. This tells the /sbin/shorewall program
|
|
where to look for the log when processing its "show log", "logwatch" and
|
|
"monitor" commands.<br>
|
|
|
|
<p><font size="2"> Updated 1/11/2003 - <a href="support.htm">Tom Eastep</a>
|
|
</font></p>
|
|
|
|
|
|
|
|
<p><a href="copyright.htm"><font size="2">Copyright</font> ©
|
|
<font size="2">2001, 2002, 2003 Thomas M. Eastep</font></a><br>
|
|
</p>
|
|
|
|
</body>
|
|
</html>
|