here’s a neat little command:
ps -ae | grep <process_name> | perl -lane ‘print $F[0]’ | while read filename; do ls /proc/$filename/fd; done | wc -w
just replace process_name by httpd for example and it’ll tell you how many file descriptions are in use by all the processes with http in them.
This assumes that you have postfix installed and running as your SMTP server
First, make sure that you’re root
whoami
I probably shouldn’t have to explain that if you’re reading this but just in case; if that last command returned something else than ‘root’ issue the following command
sudo su
and enter your password
apt-get update apt-get install spamassassin spamc
step 2: Now we configure spamassasin
cat /etc/default/spamassassin | sed -e 's#ENABLED=0#ENABLED=1#g' > /etc/default/spamassassin cat /etc/default/spamassassin | sed -e 's#CRON=0#CRON=1#g' > /etc/default/spamassassin cat /etc/spamassassin/local.cf | set -e 's## rewrite_header Subject *****SPAM*****#rewrite_header Subject [*****SPAM*****] > /etc/spamassassin/local.cf
and we start/restart it
/etc/init.d/spamassassin restart
create a user called spamassassin (or whatever you want as long as you keep it consistent)
useradd -m spamassassin
then edit the script file /home/spamassassin/spamcheck and throw the following in it
# variables
SENDMAIL="/usr/sbin/sendmail -i"
EGREP=/bin/egrep
SPAMLIMIT=10
# exit codes from <sysexits.h>
EX_UNAVAILABLE=69
# clean up when done or when aborting.
trap "rm -f /tmp/out.$$" 0 1 2 3 15
# pipe message to spamc
cat | /usr/bin/spamc -u spamd > /tmp/out.$$
# are there more than $SPAMLIMIT stars in X-Spam-Level header? :
if $EGREP -q "^X-Spam-Level: *{$SPAMLIMIT,}" < /tmp/out.$$
then
# option 1: move spam messages to sideline dir so a human can look at them later:
mv /tmp/out.$$ /home/spamassassin/`date +%Y-%m-%d_%R`-$$
# option 2: divert spam message to an alternate e-mail address:
#$SENDMAIL xyz@xxxx.xx < /tmp/out.$$
# option 3: just delete the spam message
# rm -f /tmp/out.$$
# option 4: still relay the email to the recipient with the subject of the email now containing [*****SPAM*****]
# $SENDMAIL "$@" < /tmp/out.$$
else
$SENDMAIL "$@" < /tmp/out.$$
fi
# Postfix returns the exit status of the Postfix sendmail command.
exit $?
make sure that you
chown spamassassin:spamassassin /home/spamassassin/spamcheck chmod 750 /home/spamassassin/spamcheck
edit /etc/postfix/master.cf and replace
smtp inet n - - - - smtpd
with
smtp inet n - n - - smtpd -o content_filter=spamcheck:dummy
also add the following 2 lines at the bottom of the file (the indentation is important)
spamcheck unix - n n - 10 pipe
flags=Rq user=spamassassin argv=/bin/spamcheck -f ${sender} -- ${recipient}
We’re almost there, just restart postfix and you’re good to go!
/etc/init.d/postfix restart
If you wanna test that out, watch the log while you send emails to your servers
tail -f /var/log/syslog
send a clean mail, make sure that it reaches destination, then send something you know will get flagged as spam and make sure it ends up in /home/spamassasin instead of the intended recipient.
The reason we choose option 1 here is because there’s no point in still relaying a flagged email as it will still clog the recipient’s mailbox. On the other hand we don’t want to just delete it if spamassassin makes a mistake we want to play it safe and keep every emails should something arise, we quarantine the bad ones in /home/spamassassin
Lastly, as long as you have postfix just feeding the emails to a script like we just did, it’s easy to become fancier and do all kinds of processing to the email, on my server I actually call a php script that throws emails in a DB.
If the following happens to you:
apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1 for ServerName
just issue a:
echo Servername `cat /etc/hostname` >> /etc/apache2/apache2.conf
Tested on: Ubuntu server 9.04 32b / Ubuntu 12.04 64b