Difference between revisions of "Automatic Email and Text Notifications"

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Revision as of 15:38, 1 October 2018

These tutorials describe my method of automatic messaging via email and text (SMS) from my Linux servers.

TODO:

add crontab, user/group

Required Packages

These packages are necessary for the all the following sections of this tutorial. In Debain, install them with apt-get: 

apt-get install ssmtp procmail fetchmail fetchyahoo

Directory Structure

Just for reference, here are the locations of the relevant files: 

/
├── etc
│   └── ssmtp
│       └── ssmtp.conf
└── scripts
    ├── config
    │   ├── accounts.conf
    │   ├── ddns-fetchmailrc
    │   └── ddns-mailprocess.sh
    ├── ddns.sh
    ├── email.sh
    ├── external-ip.sh
    ├── notifications.sh
    └── sms.sh

And permissions: 

ls -l /scripts

drwxr-xr-x 4 root config   4096 Jun 20 08:52 config
-rwxr-xr-- 1 root root      260 Jun 20 08:40 ddns.sh
-rwxr-xr-- 1 root mailers   564 Apr 23 12:18 email.sh
-rwxr-xr-- 1 root root      529 Apr 27 07:56 external-ip.sh
-rwxr-xr-- 1 root root     3834 May 15 08:32 notifications.sh
-rwxr-xr-- 1 root texters   545 Apr 23 12:24 sms.sh

ls -l /scripts/config

-rwxr----- 1 root mailers  147 May  1 13:01 accounts.conf
-rwxr----- 1 root config   246 May 21 09:49 ddns-fetchmailrc
-rwxr-x--- 1 root config   604 Jun 20 08:52 ddns-mailprocess.sh

Email and Text Messaging with SSMTP

First set up the /etc/ssmtp/ssmtp.conf. I use a dedicated Gmail account (named serveraccount@gmail.com in the example below) for all of my server messaging. When I receive an email from my server, it will look like it's coming from that Gmail.

Make a backup copy of the original config: 

cp /etc/ssmtp/ssmtp.conf /etc/ssmtp/ssmtp.conf.orig

Here are the contents of my modified /etc/ssmtp/ssmtp.conf. Replace the relevant values. 

#
# Config file for sSMTP sendmail
#
# The person who gets all mail for userids < 1000
# Make this empty to disable rewriting.
root=serveraccount

# The place where the mail goes. The actual machine name is required no
# MX records are consulted. Commonly mailhosts are named mail.domain.com
#mailhub=mail

# Where will the mail seem to come from?
rewriteDomain=gmail.com

# The full hostname
# This can be left as 'localhost'
hostname=localhost

# Are users allowed to set their own From: address?
# YES - Allow the user to specify their own From: address
# NO - Use the system generated From: address
FromLineOverride=YES

mailhub=smtp.gmail.com:587
UseStartTLS=YES
UseTLS=YES
AuthMethod=LOGIN
AuthUser=serveraccount@gmail.com
AuthPass=InsertPasswordHere
TLS_CA_File=/etc/pki/tls/certs/ca-bundle.crt
FromLineOverride=YES

Since the file contains a password, make sure the file is not readable to normal users. 

chown root:mail /etc/ssmtp/ssmtp.conf
chmod 640 /etc/ssmtp/ssmtp.conf

And because you don't have to remember this password, it would be a good idea to make it very long and complex (16+ characters; uppercase, lowercase, numbers, and special characters; no dictionary words).

You now need to log onto the serveraccount Gmail account and enable "less secure apps" at https://myaccount.google.com/lesssecureapps?pli=1
Gmail-less-secure-app.png

Here is more info about less secure apps: https://support.google.com/cloudidentity/answer/6260879?hl=en

You should now be able use the ssmtp command line tool from your server. Most of the time, you will need to include a subject line. It's important that it follows the format below (capital 'S' on Subject, colon, space, YourSubject, two newlines): 

echo -e "Subject: Hi\n\nHello, world!" | ssmtp myaccount@yahoo.com

Create Security Groups

I use group membership to control read access to certain files. You don't have to do this, but it was useful for me.

Create the groups: 

groupadd texters #allowed to sent text messages
groupadd mailers #allowed to send email messages
groupadd config  #allowed to read other config files

You can add a user to all three groups like this: 

usermod -aG texters,mailers,config username

Create a Secure Accounts File

For some of the automatic messaging, you need to store text and email accounts in a file. To find the destination address to send text (SMS) messages to your cell, look on your cell provider's website for the proper account/domain name. It will probably be something like "<your-phone-number>@<provider-domain>". List of provider addresses

Contents of my /scripts/config/accounts.conf file: 

#!/bin/bash
#
# Secure account information
# Permissions must be 750 root:mailers

smsto="17775551234@myprovider.net"
mailto="myaccount@yahoo.com"

Change the permissions on the file: 

chown root:mailers /scripts/config/accounts.conf
chmod 750 /scripts/config/accounts.conf

Email Script

This script can be used to send an email message.

Contents of the file /scripts/email.sh: 

#!/bin/bash

# Send email message:
#  Usage: $0 "<Subject>" "<Message>"


default_subject="Alert from Server (`date`)"

subject=""
message=""

case $# in
  2)
    subject="$1"
    message="$2"
  ;;
  1)
    subject="$default_subject"
    message="$1"
  ;;
  *)
    echo "Send Email Message:"
    echo "  Usage: `basename $0` \"Message\""
    echo "         `basename $0` \"Subject\" \"Message\""
    exit 1
  ;;
esac

dir="$(cd $(dirname ${BASH_SOURCE[0]})&&pwd)"
. $dir/config/accounts.conf

echo -e "Subject: $subject\n\n$message" | /usr/sbin/ssmtp $mailto

Set up permissions: 

chown root:mailers /scripts/email.sh
chmod 754 /scripts/email.sh

You can create an alias so you can quickly run this from the command line: 

echo "alias email='/scripts/email.sh'" >>~/.bashrc
source ~/.bashrc

Usage: 

# Send message with default subject
email "This is a test message."

# Send message with a subject
email "Test Subject" "This is a test message."

Text Script

This script can be used to send a text (SMS) message.

Contents of the file /scripts/sms.sh: 

#!/bin/bash

# Send SMS message:
#  Usage: $0 "<Subject>" "<Message>"


default_subject="Alert"

subject=""
message=""

case $# in
  2)
    subject="$1"
    message="$2"
  ;;
  1)
    subject="$default_subject"
    message="$1"
  ;;
  *)
    echo "Send SMS Message:"
    echo "  Usage: `basename $0` \"Message\""
    echo "         `basename $0` \"Subject\" \"Message\""
    exit 1
  ;;
esac

dir="$(cd $(dirname ${BASH_SOURCE[0]})&&pwd)"
. $dir/config/accounts.conf

echo -e "To: $smsto\nSubject: $subject\n\n$message" | /usr/sbin/ssmtp $smsto

Set up permissions: 

chown root:texters /scripts/sms.sh
chmod 754 /scripts/sms.sh

You can create an alias so you can quickly run this from the command line: 

echo "alias sms='/scripts/sms.sh'" >>~/.bashrc
source ~/.bashrc

Usage: 

# Send message with default subject
sms "This is a test message."

# Send message with a subject
sms "Test Subject" "This is a test message."

Scheduled Notifications Script

notifications.sh 

#!/bin/bash
#
# Send regular notifications.
# Currently set to run daily at NOON.
#

# Get current datetime values
dt=(`date +%Y\ %m\ %d\ %H\ %M\ %S\ %a\ %s\ %I\ %p\ %Z`)
y=$((10#${dt[0]})) #year
M=$((10#${dt[1]})) #month
d=$((10#${dt[2]})) #day
h=$((10#${dt[3]})) #hour(24)
m=$((10#${dt[4]})) #minute
s=$((10#${dt[5]})) #second
w=${dt[6]}         #day of week (eg. Sun)
e=$((10#${dt[7]})) #epoch
t=$((10#${dt[8]})) #hour(12)
p=${dt[9]}         #meridian (AM/PM)
z=${dt[10]}        #timezone (eg. PDT)

# Schedule command when date ($1) matched regex ($2) with extra grep parameters ($3)
# Use parameter -P at $3 for perl regex: in case you need to use (str1|str2).
# Example: schedule $M$d "(115|21)" -P && sms "Subject" "Message"
# Don't use -P when you want a range of numbers including 2 or more digit numbers (ie. [1-15]).
schedule(){ echo "$1" | grep -wq $3 "$2";}
sms(){ /scripts/sms.sh "$1" "$2";}
eml(){ /scripts/email.sh "$1" "$2";}
notify(){ sms "$1" "$2";eml "$1" "$2";}


# =================================
# ==== Temporary Notifications ====
# =================================

# Dentist appointment
#schedule $M$d "58" && notify "Dentist" "Appointment 4:00pm 10/31/2017"


# =================================
# ====== Chore Notifications ======
# =================================

# LAUNDRY DAY
# Day before
schedule $w$d "Mon[1-7]" && notify "LAUNDRY DAY" "WORK: Check gas. HOME: Do laundry, put laundry away."
schedule $w$d "Mon(15|16|17|18|19|20|21)" -P && notify "LAUNDRY DAY" "WORK: Check gas. HOME: Do laundry, put laundry away."


# WEEKLY CLEANING DAY
schedule $w "Tue" && notify "WEEKLY CLEANING DAY" "WORK: Fill gas, shopping. HOME: Clean, litter, sweep/vac, fridge, trash, check meds."
# Day after
schedule $w "Wed" && notify "WEEKLY REMINDER" "Order meds if necessary."


# MONTHLY CLEANING DAY
schedule $w$d "Tue[1-7]" && notify "MONTHLY CLEANING DAY" "WORK: Car stuff. HOME: Dishes, kitchen, bathroom, dust, inventory."


# BUSINESS DAY
schedule $d "[1-4]" && notify "BUSINESS DAY" "Rent due before 5th (\$720). Fedloan, budgeting, donations, next-buy."


# TECH DAY
schedule $w$d "Mon[1-7]" && notify "TECH DAY" "WORK: Updates, phone, healthcheck, security scan, organize files. HOME: Organize Workstation/Laptop, USB drives."


# SHOPPING DAY
schedule $w$d "Wed[1-7]" && notify "SHOPPING DAY" "Shopping, carwash. Maybe do during lunch."


# GROOMING DAY
schedule $w$d "Sun[1-7]" && notify "GROOMING DAY" "Shave/trim, clip nails."
schedule $w$d "Sun(15|16|17|18|19|20|21)" -P && notify "GROOMING DAY" "Shave/trim, clip nails."


# ELIMINATION DAY
schedule $w$d "Sun(15|16|17|18|19|20|21)" -P && notify "ELIMINATION DAY" "Do at least one item on TO_ELIMINATE list."


# INVENTORY DAY
# Disabled. Inventory is now included in monthly cleaning day.
# schedule $w$d "Tue[1-7]" && notify "INVENTORY DAY" "Do home, car, and office inventory."


# =================================
# = Other Permanent Notifications =
# =================================

# Air filter replacement notifications
schedule $M$d "71" && notify "Air Filter" "Holmes HAP726: Replace HEPA filters (model:HAPF600,qty:2)"
schedule $M$d "[1|7]1" && notify "Air Filter" "Holmes HAP726: Replace Carbon filters (model:HAPF600,qty:2)"

Reporting External IP Address

With my free dynamic DNS service, I have to renew the domain name every 30 days. So if I forgot to renew it, it would expire and I wouldn't be able to access my server if I didn't know the IP address. So I created a script that sent my external IP address to an email account every 6 hours. Then at least I would be able to see what my last IP was and I can log on to my server.

Contents of the file /scripts/external-ip.sh: 

#!/bin/bash

log="/logs/external-ip.log"
ipsrc="http://checkip.dyndns.org"
date="`date`"
addr="myaccount@yahoo.com"

ip=`curl -s --connect-timeout 3 $ipsrc 2>/dev/null|grep -Po "Current IP Address: .*?\<"|tr '<' '\0'`
echo "IP: $ip"

if [ -z "$ip" ];then
	echo "$date ERROR: Could not get external IP from $ipsrc" >>$log
else
	echo -e "Subject:[`hostname`] $date $ip" | /usr/sbin/ssmtp $addr
	if [ "$?" = "0" ];then
		echo "$date SUCCESS: $ip sent to $addr" >>$log
	else
		echo "$date ERROR: Could not send to $addr" >>$log
	fi
fi

Automatic Email Download

Contents of the file /scripts/ddns.sh: 

#!/bin/bash

/usr/bin/fetchmail -N -d0 -f "/scripts/config/ddns-fetchmailrc" -m "/scripts/config/ddns-mailprocess.sh"

alertfile="/shares/Private/000__DDNS-ALERT__.txt"
if [ -e $alertfile ];then
	chown root:root $alertfile
	chmod 777 $alertfile
fi

ddns-mailprocess.sh 

#!/bin/bash

mailto="17775551234@myprovider.net"
date="`date`"
log="/logs/ddns.log"
alertfile="/shares/Private/000__DDNS-ALERT__.txt"
sms="/scripts/sms.sh"

cat /dev/stdin | grep -i "^Subject:" | sed 's/Subject\://g' | $sms "DDNS" "`cat /dev/stdin` ( $date )" &&\
echo "$date - DDNS notification sent to $mailto" | tee -a $log | sed "s/$mailto/cell\ phone/g" >$alertfile &&\
chmod 777 $alertfile

ddns-fetchmailrc 

#
# This file MUST have user root and chmod 700
#
#set syslog;
#set daemon 90;

set postmaster "username";

poll "imap.mail.yahoo.com" protocol IMAP username "myaccount@yahoo.com" password "InsertPasswordHere" is "username" here keep folder "DDNS-Mailbox" ssl
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