This small script is inspired by AlterMIME. but does a very specific task Unlike just appending a disclaimer text in a mail, it looks for a specific set of words in a mail and replaces that with a link. This was specifically developed for Discourse to replace link_url
or show_url
with a URL based on a subdomain value fetched from custom fields in the discourse database. You are most welcome to take and break it for your needs !!
Cheers,
Anindya Roy
i@anindya.me
Any Linux distribution with bash and Postfix already installed and running
Download dmProxy.sh
and dmProxy.conf
or simply do a git clone of this folder. I recommend to do it in a folder like /opt/dmProxy. But you are welcome to use your imagination. then move dmProxy.conf
to /etc/
Now open the /etc/dmProxy.conf
file in your favorit text editor and localize it with your system settings. Everything is commented pretty well. Though I am bad with spellings so pardon my typos ;-) ! here is a quick list of what all you would need to replace
Line 3: INSPECT_DIR=/var/spool/filter
-- This is the folder where the mails will be captured and worked on. we will create it in the next step
Line 5: SENDMAIL=/usr/sbin/sendmail
-- Your sendmail location. do a whereis sendmail
to find this
Line 7: HTTP="https"
-- Change it with what suites you. HTTP or HTTPS. this will be appended at the beginning of the link
Line 9: DOMAIN="monitoringclient.com"
-- Your domain goes here
Line 11: export PGPASSWORD=""
-- Put your Postgres Password Here. yes plain text. bad idea. there are other ways to do this aswell. do some googling ;-)
Line 13: dbHost=""
-- Put your PostgreSQL Hostname or IP here
Line 15: dbName=""
-- And DB Name Goes here. most likely it will be discourse.
Line 17: dbUser=""
-- Finally the db user. Remember the plain text password in line 21? create a readonly DB user and use it for this script.
And you are pretty much done with the script
Create a folder where your mails will be kept while parsing. This folder needs to be secure enough so we will create a dedicated user for running our proxy and accessing this folder in next step
#mkdir /var/spool/filter
Create a user called filter like this
#useradd -r -c "Postfix Filters" -d /var/spool/filter filter
Now make sure the folder /var/spool/filter is owned by the filter user
#chown filter:filter /var/spool/filter
and tighten the security a bit
#chmod 750 /var/spool/filter
Also, as the user is now created. lets give our shell script rights to be run by filter group
#chown root.filter /opt/dmProxy/ -R
and make it executable
#chmod 755 /opt/dmProxy/dmProxy.sh
Now open postfix's master.cf with your favorit text editor and add a line just below
smtp inet n - y - - smtpd
-o content_filter=dmProxy:dummy #This is the line to be added
NOTE: if you are using smtps then you have to append the same line below smtps as well. This should look like
smtps inet n - y - - smtpd
-o content_filter=dmProxy:dummy
And now you have to define the dmProxy content filter that you have just created. go to the end of master.cf and append the following 2 lines
dmProxy unix - n n - - pipe
flags=Rq user=filter argv=/opt/dmProxy/dmProxy.sh -f ${sender} -- ${recipient}
And finally restart postfix
#/etc/init.d/postfix restart
and you are done !! wasn't it easy ;-) ?