Raspberry PI sending emails

Using the PI as an headless server doing some stuff, it’s a good thing to have reports by email. The best and easy way is to run sSMTP a very simple program that sends outgoing email to a mailhub for delivery.

You can actually use your Gmail account or any other account (I’m using any other account).

Install it:

apt-get install ssmtp

Configure it at /etc/ssmtp/ssmtp.conf. The most relevant option:

mailhub=mail.domain.com (the SMTP agent host, the “outgoing server” in email clients like thunderbird)

If your outgoing server needs authentication for relaying (probably you do need, if you can send emails to your own domain emails, but can’t send to external emails), set the credentials with these two options:
AuthUser=youruser@domain.com
AuthPass=yourpassword

To test it, i executed the good old mail command but get a no-no response:
-bash: mail: command not found

As Raspbian is Debian based, the “user-friendliness” doesn’t provide these stone age commands to protect one from oneself… so I went kind of mental and install it anyway:

apt-get install mailutils


After this operation, 22,8 MB of additional disk space will be used.
Do you want to continue? [Y/n] y

OH BOY, THAT’S A FUCKING LOTS OF MB/PACKAGES/DEPENDENCIES TO GET A CLI COMMAND

mail youremail@domain.com

in the interactive mode, just follow the instructions, write some non-sense to test it and then press CTRL-D to test it. And your email should automagically appear in youremail@domain.com inbox.

If something goes wrong, you can add DEBUG=YES to /etc/ssmtp/ssmtp.conf.

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Raspberry PI running from an external HDD

This is a scenario where you have an external HDD (or “pen” drive) connected via USB to the PI. The SD card will be just used for the boot sequence then everything will work from the external HDD, I find the system to work faster, smoother and more stable this way (at least with my v1 PI).

First thing is to normally install the Raspbian system in the SD card. There will be 2 partitions on it. A first small fat16 partition labeled ‘boot’ with the lba flag set, and a second ext4 partition. So, on your external HDD you will need also a ext4 partition. I advice you to to make 2 partitions in the HDD, one for the OS, programs and files, and the second (like a /home/ or /data/) for personal files, backups, etc. In the event of a major catastrophic malfunction, this configuration offers a bigger safeguard to your personal data.

If you need assistance to partition and format your HDD probably its a good idea to stop here.

Mount and sync the second SD card ext4 partition with your external HDD ext4 partition

sudo rsync -avHx /mnt/sdcard/ /mnt/hdd

Next step is to mount the SD card boot partition. And change in /cmdline.txt (adjust sda1 to your HDD partition as needed).

root=/dev/mmcblk0p2 

to

root=/dev/sda1 rootwait

You can actually delete de SD card system directory (or not) it works the same. Also don’t forget to add an entry in /etc/fstab for mounting the second partition in the HDD in case you have it.

Good luck with your PI.

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2016 Zeitgeist

Watch my beautiful son being born.
Watch Portugal win the UEFA Euro 2016 with an Éder goal.

Any year with this 2 events can only be an awesome year. Won’t write much more, because I have lots of time to recover.

 

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Letter to Lawrence

Hi Lawrence,

Lourençoyou were born the 3rd of June 2016 in a clear sky, Friday spring afternoon. The staff at Hospital S. Francisco Xavier was super and the birth was perfect, and if by chance one day you bump into nurse Fátima from obstetrics you give her a big hug.

I was very lucky to watch you born and cut the umbilical cord. Everybody told me that you born a very beautiful baby, but the most important thing for me is that you were born a healthy baby.

So first of all, welcome into this world 🙂

I wish your life to be full and long. Full with good people and good energy. I hope you will grow a kind-hearted, honest, correct, strong, intelligent, curious, deep and interesting person.

I don’t know when everything changed, but now every time I look at you, I see the whole universe, there are really no words to express these powerful feelings. And when you smile (and you do smile a lot) well I don’t care about anything else.

You are part of me and I am part of you. So, I make the this vote of protecting you forever. Any time you need me, I will be there. With all my love.

Your old man,
Marco Gonçalves

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Procmail with Qmail + Vpopmail

Following the qmail threads in this blog, and after a successful experience filtering emails in the server with a php script! time was upon to thinker a bit with the elder of all email server filters, Procmail – the mail processing utility for Unix.

Whe are talking really old stuff, as Wikipedia states the initial release in 1990, so 26 years from this writing, and about a zillion years in computer time (a date so old that it’s closer to the Unix Epoch than it is of today).

As usual, the easy part in FreeBSD is the installation:

cd /usr/ports/mail/procmail
make install

there. Now the tricky part, that is to make it play nicely with Qmail+Vpopmail setup. For the first experiences you probably should setup a couple of test accounts.

The concept is pretty simple, for an account that you want to filter email with Procmail we are going to add/or change the .qmail file that controls the email delivery to a filter script that invokes procmail and throw back a proper qmail exit code according to Procmail result.

It is very important to take into account that in this setup Procmail DOES NOT deliver the email directly, it filters the email, and according with the recipes rules, it can stop the delivery chain, forward the email, invoke an external command, etc.

Without further delays. The customized .qmail that calls the filter script:

| /home/vpopmail/domains/mydomain.com/teste/procmail_filter
/usr/home/vpopmail/domains/mydomain.com/teste/Maildir/

this is pretty simple and standard stuff. The qmail-local parses the .qmail file. The line with a pipe means to feed the message to the specified program. The command is invoked by qmail-command that runs sh -c command in the home directory, makes the email messsage available on standard input and setups some environment variables.

For this thread the most important stuff are the exit codes:

Command’s exit codes are interpreted as follows:
0 means that the delivery was successful;
99 means that the delivery was successful, but that qmail-local should ignore all further delivery instructions;
100 means that the delivery failed permanently (hard error);
111 means that the delivery failed but should be tried again in a little while (soft error).
Currently 64, 65, 70, 76, 77, 78, and 112 are considered hard errors, and all other codes are considered soft errors, but command should avoid relying on this.

With this info it’s pretty straight forward to devise the procmail_filter script.

#!/bin/sh

/var/qmail/bin/preline /usr/local/bin/procmail ./.procmailrc

status=$?

if [ $status -eq 99 ]
then
  status=99
elif [ $status -eq 0 ]
then
  status=0
elif [ $status -le 77 ]
then
  status=111
else
  status=100
fi

exit $status

and mark it executable.

The first line (after the shebang) the script calls qmail preline program, it simply inserts at the top of each message a UUCP-style From_ line, a Return-Path line, and a Delivered-To line because Procmail doesn’t understand the qmail environment variables. Calls procmail and sets Procmail configuration file the .procmailrc in the same directory.

Now for the .procmailrc stripped down to a very simple example:

SHELL = /bin/sh
LOGFILE=./pm.log
LOG="
"
VERBOSE=yes

# Exitcodes
# 0 normal delivery
# 99 silent discard a message
# 100 bounce a message

# Recipes

:0
* ^From: email@domain.com
{
  EXITCODE=99

  :0
  | /usr/local/libexec/dovecot/deliver -d delivertothis@email.com

}

# Avoid duplicates
:0
/dev/null

The top lines are the configuration variables, I would strongly suggest to use a log file for testing, in this example called pm.log that lives in the same directory. The strange LOG directive simple adds a new line to each log entry.

Then the recipes, in this example we match all emails from email@domain.com and deliver it to a local email delivertothis@email.com using Dovecot deliver command (so it takes care of Maildir quota), and set exitcode 99 to discard the message. Exit code 99 means that the delivery was successful, so all .qmail further delivery instructions will be ignored.

We could simply put an email address for a external email address, or even a local address but with less efficiency as it will trigger a new delivery process. This is auto-magical thanks to FreeBSD mailer.conf wrapper.

:0
* ^From: email@domain.com
{
  EXITCODE=99

  :0
  delivertothis@email.com

}

The last lines avoid duplicates, Procmail /dev/nulls the message and gives back the delivery control to the .qmail flow.

That’s it, everything playing nice with each other in old good UNIX tradition.

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