Postfix Monitoring With Mailgraph And pflogsumm
Author: Falko Timme <ft [at] falkotimme [dot] com>
Last edited 06/23/2006
This article describes how you can monitor your Postfix mailserver with the tools Mailgraph and pflogsumm. Mailgraph creates daily, weekly, monthly, and yearly graphs of sent, received, bounced, and rejected emails and also of spam and viruses, if SpamAssassin and ClamAV are integrated into Postfix. These graphs can be accessed with a browser, whereas pflogsumm ("Postfix Log Entry Summarizer") can be used to send reports of Postfix activity per email.
In the following I will describe how to install and configure Mailgraph and pflogsumm on Debian Sarge, Ubuntu Dapper Drake (6.06 LTS), and Fedora Core 5.
I want to say first that this is not the only way of setting up such a system. There are many ways of achieving this goal but this is the way I take. I do not issue any guarantee that this will work for you!
1 Preliminary Note
In this tutorial my Linux system has the IP address 192.168.0.100 and hosts the web site http://www.example.com with the document root /var/www/www.example.com/web and a cgi-bin directory of /var/www/www.example.com/cgi-bin, and I will send the pflogsumm reports to the email address firstname.lastname@example.org.
2 Debian Sarge
Debian Sarge has packages for Mailgraph and pflogsumm, so we simply install these. We also install rrdtool that stores the data which is needed by Mailgraph to draw the graphs:
apt-get install rrdtool mailgraph
You will be asked a few questions:
Should Mailgraph start on boot? <-- Yes
Which logfile should be used by mailgraph? <-- /var/log/mail.log
Remove RRD files on purge? <-- Yes
Then there's also this question:
Count incoming mail as outgoing mail?
If you have integrated a content filter like amavisd (for spam and virus scanning) into Postfix (like in this tutorial: Virtual Users And Domains With Postfix, Courier And MySQL (+ SMTP-AUTH, Quota, SpamAssassin, ClamAV)), then answer No to avoid that Mailgraph counts your emails twice (because Postfix delivers emails to amavisd which then - after successful scanning - delivers the mails back to Postfix). If you don't use a content filter, then answer Yes.
During the installation, the system startup links for Mailgraph are created automatically, and Mailgraph also gets started automatically, so we don't need to start it manually.
Now we must copy the mailgraph.cgi script (which draws the graphs and creates the output for our web browsers) to the cgi-bin directory of our www.example.com web site:
cp -p /usr/lib/cgi-bin/mailgraph.cgi /var/www/www.example.com/cgi-bin
The script is already executable, so we don't need to chmod it. If you use suExec for the www.example.com web site, you must chown mailgraph.cgi to the appropriate owner and group.
Now direct your browser to http://www.example.com/cgi-bin/mailgraph.cgi, and you should see some graphs. Of course, there must be some emails going through your system before you see the first results, so be patient.
After some time your graphs could look like this (the following output is customized, so it doesn't look exactly like yours):
Please note: Mailgraph will report spam and viruses only if you have integrated a content filter like amavisd into Postfix which is configured to use SpamAssassin and ClamAV to tag spam and virus mails. If you don't do this, you will still see graphs, but without the spam and virus report.
To install pflogsumm, we run
apt-get install pflogsumm
We want pflogsumm to be run by a cron job each day and send the report to email@example.com. Therefore we must configure our system that it writes one mail log file for 24 hours, and afterwards starts the next mail log so that we can feed the old mail log to pflogsumm. Therefore we configure logrotate (that's the program that rotates our system's log files) like this: open /etc/logrotate.conf and append the following stanza to it, after the line # system-specific logs may be configured here:
There's a logrotate script in /etc/cron.daily. This script is called everyday between 06:00h and 07:00h. With the configuration we just made, it will copy the current Postfix log /var/log/mail.log to /var/log/mail.log.0 and compress it, and the compressed file will be /var/log/mail.log.0.gz. It will also create a new, empty /var/log/mail.log to which Postfix can log for the next 24 hours.
Now we create the script /usr/local/sbin/postfix_report.sh which invokes pflogsumm and makes it send the report to firstname.lastname@example.org:
pflogsumm /var/log/mail.log.0 | formail -c -I"Subject: Mail Statistics" -I"From: pflogsumm@localhost" -I"To: email@example.com" -I"Received: from www.example.com ([192.168.0.100])" | sendmail firstname.lastname@example.org
We must make this script executable:
chmod 755 /usr/local/sbin/postfix_report.sh
Then we create a cron job which calls the script everyday at 07:00h:
0 7 * * * /usr/local/sbin/postfix_report.sh &> /dev/null
This will send the report to email@example.com. It looks like this in an email client: