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Tweaking PLA: Using rsyslog

PLA (PIX Logging Architecture) uses regular expressions (regex) to parse syslog messages received from Cisco firewallsand comes pre-configured to process standard “syslogd” message format. Most current Linux distributions ship with rsyslog (able to log directly to MySQL) while some administrators prefer syslog-ng.

The installation documentation distributed with PLA assumes a familiarity regex, so here you’ll see how to tweak PLA to parse your rsyslogd log file.

Perl is used to parse through the syslog message looking for matches to message formats described in the syslog_messages table in the pix database. The processing script pla_parsedcontains a regex pattern that must be matched in order for the processing to occur. The applicable section is:

### PIX Firewall Logs
$regex_log_begin = “(.*):(.*) (.*) (.*) (.*) (.*) (.*)“;

Here, the variable regex_log_beginneeds to match up all the log information up to the PIX, ASA, or FWSM message code in order to understand date, time, and host for these messages. Take a look at the provided sample log entry, everything in red needs to be picked up by regex_log_begin while the remainder is standard for Cisco firewalls:

Oct 21 23:59:23 fwext-dmz-01 Oct 21 2006 23:58:23: %PIX-6-305011: Built dynamic TCP translation from inside: to outside:

Explaining the operation of regex and wildcards is beyond the scope of this article; however, numerous guides have been written to fill the void. In our case, adjusting the default regex to match rsyslog is straight forward after noting which characters match which pattern, again we’re working with the basics of regex here – nothing fancy.

Take this sample rsyslog entry and notice the difference from the standard syslogd format:

Feb 21 10:59:32 Feb 21 2008 10:59:32 pix4us : %PIX-6-110001: No route to from

Feb 21 10:59:32 Feb 21 2008 10:59:32 pix4us
Oct 21 23:59:23 fwext-dmz-01 Oct 21 2006 23:58:23

Here, the rsyslog entry includes the date twice and then the hostname of the log source versus the default format expected by pla_parsedof date hostname date. The original regex is set to pickup the first time entry’s “minutes and seconds” and picks up the next 5 words/entries separated by spaces:

$regex_log_begin = “(.*):(.*) (.*) (.*) (.*) (.*) (.*)“;

 Oct 21 23:59:23 fwext-dmz-01 Oct 21 2006 23:58:23

In order to process rsyslog, this will have to be changed. The initial (.*):(.*) is used to set a starting point in syslog message string. Since this new rsyslog format includes two date entries before the host name, the following can be used to allow pla_parsedto “see” the new syslog message string:

$regex_log_begin = “(.*):(.*) (.*) (.*) (.*) ((.*):(.*):(.*)) (.*)“;

Feb 21 10:59:32 Feb 21 2008 10:59:32 pix4us

The regex starts out the same, but looking at the colors you will notice the location of the information needed by pla_parsed to determine date, time, and host has moved. This time we used “(.*):(.*)” and “((.*):(.*):(.*))” to force a match on the time elements.

As a result of this change, the variables listed below the regex pattern must be modified to tell pla_parsed which (.*) contains which element:

$regex_log_begin = “(.*):(.*) (.*) (.*) (.*) ((.*):(.*):(.*)) (.*)“;


The numbering happens left to right and the color coding should help this make sense. The ()’s around the grey time entry are grouped together and count as one match/entity, the sixth variable. This same approach of keying off the timestamping can be applied to pla_parsedin order to allow processing of syslog-ng, ksyslogd, or any other syslog message format.

Need help with a different format? Have problems getting your PIX logs loaded? Paste in a sample message from your syslog server (IP Addresses santized please) in a comment below.


PIX Parsing (Usable Logs!)

If you have a Cisco PIX you are responsible for, don’t have a logging solution for it, or haven’t seen PLA, keep reading you’re going to be impressed. PDM is out and ASDM is an improvement but who wants to run https-server on a firewall?

There are plenty of commercial solutions available, some just perform log analysis and others attempt to perform event correlation. If you just want to solve the logging problem and are unable to implement a log collection system, take a look at PIX Logging Architecture.

I recently implemented Pix Logging Architecture (PLA) to help manage FWSM, PIX, and ASA logs. I hate having to cull through syslog files looking for traffic stats, tcp port usage, or accepted vs denied traffic information. This point and click world we live in has me spoiled, I don’t want to CLI everything – especially when I’m headed into a meeting to discuss who has access to the Oracle Applications database server.

What if you could get a daily snapshot of your firewall(s)? How about running queries instead of text-based finds? The following log messages are already supportedand reg-ex can be used to further extend the capabilities. Defining traffic types and being able to make graphs? Once you involve a database, you have to decide how often to purge the data.

If you like that and aren’t afraid of using open source, you’ll need apache, MySQL, perl (with some additional modules), syslog daemon or the syslog file, and one more Cisco PIX, ASA, or FWSMs. The OS is up to you, but Linux is highly recommended.

What is PLA?

The PIX Logging Architecture [PLA] is a free and open-source project allowing for correlation of Cisco PIX, Cisco FWSM and Cisco ASA Firewall Traffic, IDS and Informational Logs.

PIX Log message parsing is performed through the use of the PLA parsing module or PLA Msyslogd module. Centralization of the logs is provided using a MySQL database, supported by a Web-based frontend for Log Viewing, Searching, and Event Management. PIX Logging Architecture is completely coded in the Perl programming language, and uses various Perl modules including Perl::DBI and Perl::CGI.

Where is PLA?

PLA’s website has been down since late December but Kris reports it’s BACK ONLINE! If you are interested in downloading the software or documentation, you can find it on SourceForge but your best bet is to go directly to the source itself: PIX Logging Architecture.

I’m working on uploading the documentation and some tweaks to pull in Cisco IPS Event Viewer data into the IDS tab onto my other website, but haven’t been able to reach the original author (Kris) yet.  

How does PLA work?

The PLA software is divided into a parsing piece, database server, and web front-end. Depending on your security policy, network zoning, and server capabilities, you can run this on one server or spread it across several. I was fortunate enough to have access to a dual processor duo2 server, so I implemented everything on the same Linux server.

The underlying architecture is very clever. Message formats are loaded into memory and the syslog file is tailed (via perl module). Messages are flagged by type and processed accordingly, in near-real-time:

The PIX Logging Architecture parsing module, which is responsible for extracting the necessary fields from the PIX system log messages, has been extended to gather new information including, but not limited to, Translations (Xlate’s), Informative Log Messages (i.e. PIX Failover, PIX VPN Establishment, PIX Interface Up/Down, PIX PPPoE VPDN establishment and the like). All the parsing information needed by the PLA Parsing Daemon (pla_parsed) in order to extract data from the logs is now stored in the database, allowing for easy updates of the supported log messages without having to replace the parsing scripts. Moreover, the PLA Parsing Daemon runs as a daemonized Perl process in the background and reads straight and in quasi real-time from the system log files, so no more need to create crontab jobs like before and having to restart syslogd all the time.

The PLA Team has created detailed documentation for installing, tweaking, and supporting PLA. [edit: Google cache of documentation. PLA Documentation can be downloaded at SourceForge].

 In order to get started, you’ll want to read through the first few sections to get a feel for what will be required and figure out what you’ll need in your environment. For example, if you run standard syslogd the parsing of the syslog file works one way and if you run ksyslog or syslog-ng you’ll need to make adjustments. Section 5.5 of the documentation covers tweaking the regex for parsing other syslog engine formats. The documentation explains centralized installation versus distributed, as well as what ports and services will be needed on the server(s).

Security is obviously a concern when processing security log files. Securing the MySQL database access and Apache access is recommended. I would also recommend securing the server itself, if you’re new to Linux this may help.