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Postfix Monitoring With Mailgraph And pflogsumm


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 postmaster@example.com.

 

2 Debian Sarge

 

2.1 Mailgraph

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):

1

Daily Statistics.

2

Weekly Statistics.

3

Monthly Statistics.

4

Yearly Statistics.

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.

 

2.2 pflogsumm

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 postmaster@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:

vi /etc/logrotate.conf

/var/log/mail.log {
    missingok
    daily
    rotate 7
    create
    compress
    start 0
}

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 postmaster@example.com:

vi /usr/local/sbin/postfix_report.sh

#!/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
gunzip /var/log/mail.log.0.gz

pflogsumm /var/log/mail.log.0 | formail -c -I"Subject: Mail Statistics" -I"From: pflogsumm@localhost" -I"To: postmaster@example.com" -I"Received: from www.example.com ([192.168.0.100])" | sendmail postmaster@example.com

gzip /var/log/mail.log.0
exit 0

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:

crontab -e

0 7 * * * /usr/local/sbin/postfix_report.sh &> /dev/null

This will send the report to postmaster@example.com. It looks like this in an email client:

5

3 Ubuntu Dapper Drake (6.06 LTS)

 

3.1 Mailgraph

To install Mailgraph, we run

apt-get install rrdtool mailgraph

Ubuntu doesn’t ask us questions. Nevertheless, we have to make the differentiation if we use a content filter like amavisd in Postfix or not. Open /etc/default/mailgraph:

vi /etc/default/mailgraph

If you use a content filter like amavisd, the file should have the following contents:

MAIL_LOG=/var/log/mail.log
IGNORE_LOCALHOST=true

If you don’t, then it should look like this:

MAIL_LOG=/var/log/mail.log
IGNORE_LOCALHOST=false

Ubuntu doesn’t create the system startup links for Mailgraph automatically, so we do it now:

update-rc.d mailgraph defaults

Also, we have to start Mailgraph now:

/etc/init.d/mailgraph start

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.

 

3.2 pflogsumm

The pflogsumm part is exactly the same as for Debian Sarge:

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 postmaster@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:

vi /etc/logrotate.conf

/var/log/mail.log {
    missingok
    daily
    rotate 7
    create
    compress
    start 0
}

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 postmaster@example.com:

vi /usr/local/sbin/postfix_report.sh

#!/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
gunzip /var/log/mail.log.0.gz

pflogsumm /var/log/mail.log.0 | formail -c -I"Subject: Mail Statistics" -I"From: pflogsumm@localhost" -I"To: postmaster@example.com" -I"Received: from www.example.com ([192.168.0.100])" | sendmail postmaster@example.com

gzip /var/log/mail.log.0
exit 0

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:

crontab -e

0 7 * * * /usr/local/sbin/postfix_report.sh &> /dev/null

This will send the report to postmaster@example.com.

4 Fedora Core 5

 

4.1 Mailgraph

There’s no Mailgraph package available for Fedora Core 5, so we must install it manually. First, we need to install the prerequsities that Mailgraph requires:

yum install rrdtool rrdtool-perl perl-File-Tail

Then we download the Mailgraph sources and copy the Mailgraph scripts to the appropriate locations:

cd /tmp
wget http://people.ee.ethz.ch/~dws/software/mailgraph/pub/mailgraph-1.12.tar.gz
tar xvfz mailgraph-1.12.tar.gz
cd mailgraph-1.12
mv mailgraph.pl /usr/local/bin/mailgraph.pl
mv mailgraph-init /etc/init.d/mailgraph

Now we must adjust the Mailgraph init script /etc/init.d/mailgraph:

vi /etc/init.d/mailgraph

On Fedora, the Postfix mail log is /var/log/maillog, so we change

MAIL_LOG=/var/log/syslog

to

MAIL_LOG=/var/log/maillog

Then we add another variable to /etc/init.d/mailgraph, IGNORE_LOCALHOST. If you have integrated a content filter like amavisd into Postfix, add this line

IGNORE_LOCALHOST="--ignore-localhost"

to the block where the variables like MAIL_LOG are defined. If you don’t use a content filter, add this line instead:

IGNORE_LOCALHOST=""

In both cases, change

        nice -19 $MAILGRAPH_PL -l $MAIL_LOG -d \
                --daemon-pid=$PID_FILE --daemon-rrd=$RRD_DIR

to

        nice -19 $MAILGRAPH_PL -l $MAIL_LOG -d \
                --daemon-pid=$PID_FILE --daemon-rrd=$RRD_DIR $IGNORE_LOCALHOST

So the final script should look like this (in this case, with –ignore-localhost enabled):

#!/bin/sh

# $Id: mailgraph-init,v 1.4 2005/06/13 11:23:22 dws Exp $
# example init script for mailgraph
#
# chkconfig: 2345 82 28
# description: mailgraph postfix log grapher.
#
# processname: mailgraph.pl
# pidfile: /var/run/mailgraph.pid


PATH=/bin:/usr/bin
MAILGRAPH_PL=/usr/local/bin/mailgraph.pl
MAIL_LOG=/var/log/maillog
PID_FILE=/var/run/mailgraph.pid
RRD_DIR=/var/lib
IGNORE_LOCALHOST="--ignore-localhost"

case "$1" in
'start')
        echo "Starting mail statistics grapher: mailgraph";
        nice -19 $MAILGRAPH_PL -l $MAIL_LOG -d \
                --daemon-pid=$PID_FILE --daemon-rrd=$RRD_DIR $IGNORE_LOCALHOST
        ;;

'stop')
        echo "Stopping mail statistics grapher: mailgraph";
        if [ -f $PID_FILE ]; then
                kill `cat $PID_FILE`
                rm $PID_FILE
        else
                echo "mailgraph not running";
        fi
        ;;

*)
        echo "Usage: $0 { start | stop }"
        exit 1
        ;;

esac
exit 0

Next we make the script executable, create the appropriate system startup links and start Mailgraph:

chmod 755 /etc/init.d/mailgraph
chkconfig –levels 235 mailgraph on
/etc/init.d/mailgraph start

Still in the /tmp/mailgraph-1.12 directory, we move mailgraph.cgi to our cgi-bin directory:

mv mailgraph.cgi /var/www/www.example.com/cgi-bin/

Now we open the file and adjust the locations of the two Mailgraph databases.

vi /var/www/www.example.com/cgi-bin/mailgraph.cgi

Change

my $rrd = 'mailgraph.rrd'; # path to where the RRD database is
my $rrd_virus = 'mailgraph_virus.rrd'; # path to where the Virus RRD database is

to

my $rrd = '/var/lib/mailgraph.rrd'; # path to where the RRD database is
my $rrd_virus = '/var/lib/mailgraph_virus.rrd'; # path to where the Virus RRD database is

Then we make the script executable:

chmod 755 /var/www/www.example.com/cgi-bin/mailgraph.cgi

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.

 

4.2 pflogsumm

The steps differ only slightly from those on Debian and Ubuntu. The main difference is that Postfix logs to /var/log/maillog on Fedora instead of /var/log/mail.log (Debian/Ubuntu) (pay attention to the dot!).

First we install pflogsumm:

yum install postfix-pflogsumm

We want pflogsumm to be run by a cron job each day and send the report to postmaster@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:

vi /etc/logrotate.conf

/var/log/maillog {
    missingok
    daily
    rotate 7
    create
    compress
    start 0
}

Also change /etc/logrotate.d/syslog

vi /etc/logrotate.d/syslog

from

/var/log/messages /var/log/secure /var/log/maillog /var/log/spooler /var/log/boot.log /var/log/cron {
    sharedscripts
    postrotate
        /bin/kill -HUP `cat /var/run/syslogd.pid 2> /dev/null` 2> /dev/null || true
    endscript
}

to

/var/log/messages /var/log/secure /var/log/spooler /var/log/boot.log /var/log/cron {
    sharedscripts
    postrotate
        /bin/kill -HUP `cat /var/run/syslogd.pid 2> /dev/null` 2> /dev/null || true
    endscript
}

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/maillog to /var/log/maillog.0 and compress it, and the compressed file will be /var/log/maillog.0.gz. It will also create a new, empty /var/log/maillog 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 postmaster@example.com:

vi /usr/local/sbin/postfix_report.sh

#!/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
gunzip /var/log/maillog.0.gz

pflogsumm /var/log/maillog.0 | formail -c -I"Subject: Mail Statistics" -I"From: pflogsumm@localhost" -I"To: postmaster@example.com" -I"Received: from www.example.com ([192.168.0.100])" | sendmail postmaster@example.com

gzip /var/log/maillog.0
exit 0

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:

crontab -e

0 7 * * * /usr/local/sbin/postfix_report.sh &> /dev/null

This will send the report to postmaster@example.com.

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