Quick and Dirty pop before SMTP

There are many solutions to implement pop before SMTP including
a perl script that claims "to do it all". Recently i needed
to implement this quickly - so rather than wading through other people's
code i hacked together a system that works well.

Note that the scripts will have to be modified for use on other systems
, however they are so trivially easy that anyone who has done a little
shell scripting and sysadmin should be able to do it. The script as it is
is sendmail specific, but it can be adapted to postfix in just a couple of
minutes.

First you need to edit your syslog.conf to log all of your pop logs to a
throwaway file.

To do this, add a line like this to your syslog.conf be sure to use tabs
rather than spaces when you enter the lines.



!pop3d
*.*                                             /var/log/pop3d

Create the logfile and reload your syslogd by doing:

# touch /var/log/pop3d
# ps -ax | grep syslogd
42051  ??  Ss     5:06.54 syslogd
# kill -1 42051

Edit this script to properly get the ip addresses of authenticated users
from the new logfile you just created.

#!/bin/sh

PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin:/usr/local/bin
export PATH

for ip in `grep LOGIN /var/log/pop3d  | \
    awk '{print $8}' | \
    awk -F: '{print $4}'| \
    sed '/]/s/]//g' | \
    sort | \
    uniq | \
    egrep -v '127.0.0.1|10.10.10.10|192.168.0|0.0.0.0'`
do
    date > /var/spool/popauth/${ip}
done 

ls /var/spool/popauth/ | awk '{print $1 "    RELAY"}' > /etc/mail/popaccess
cat /dev/null > /var/log/pop3d
cat /etc/mail/access /etc/mail/popaccess | makemap hash /etc/mail/access.db 2>&1 > /dev/null

relay.txt Script only.

Add the script to your crontab - i run it every minute for users who were
accustomed to using a proprietary mailserver that does not run on unix.

*       *       *       *       *       /usr/local/bin/relay

All that is needed now is to remove the entries from /var/spool/popauth
That are old so as to prevent your mailserver from being used as a spam
relay. I wrote a very quick c program to accomplish this.

cleanpopauthdir.txt

I run this program every 15 minutes from Cron to clean out entries that have
not been updated in 30 minutes.