Monitoring & Update email notification via GMail on Ubuntu Linux Servers

System notification emails

Continuing in part off of my last Ubuntu Server article, "The Perfect Server", I decided that i wanted the server to send me emails updating its status with me. If the HD space gets low, the RAM is all used up, services go down, or even i lose internet at my house while im out and about, i get a nice email from my server notifying me of the problem (at least when my inet comes back online).

What better way to top this off than with use of a gmail account that i already owned and used?

In this article, i will walk you through installing the following along side your postfix installation:

Self signed SSL certfication (don't want anyone being nosey!)

Apticron - A nice set of scripts that will execute 'apt-get udpate' and email you the results

Webmin - One of the best web based management consoles for head-less servers. Has a great system notification setup, along with many many many other goodies.

Note: This how-to assumes you've already installed Postfix mail server on an Ubuntu Linux Server (sudo apt-get postfix)

1) Create a Certificate Authority

# sudo /usr/lib/ssl/misc/CA.pl -newca

Output:

CA certificate filename (or enter to create)

Making CA certificate …
Generating a 1024 bit RSA private key
…….++++++
……………….++++++
writing new private key to ‘./demoCA/private/cakey.pem’
Enter PEM pass phrase: password
Verifying – Enter PEM pass phrase: password
—–
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter ‘.’, the field will be left blank.
—–
Country Name (2 letter code) [US]:US
State or Province Name (full name) [New York]:California
Locality Name (eg, city) []:Los Angeles
Organization Name (eg, company) []:TimAshley.me

Organizational Unit Name (eg, section) []:
Common Name (eg, YOUR name) []:Tim
Email Address []: tim@timashley.me

Please enter the following ‘extra’ attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:
Using configuration from /usr/lib/ssl/openssl.cnf
Enter pass phrase for ./demoCA/private/cakey.pem:
Check that the request matches the signature
Signature ok

2) Create a Server Certificate

# sudo openssl req -new -nodes -subj '/CN=domain.com/O=Sanborn_Widgets/C=US/ST=New York/L=New York/emailAddress=username@gmail.com' -keyout FOO-key.pem -out FOO-req.pem -days 3650

3) Sign the Certificate

# sudo openssl ca -out FOO-cert.pem -infiles FOO-req.pem

Output:

Using configuration from
/usr/lib/ssl/openssl.cnf
Enter pass phrase for ./demoCA/private/cakey.pem:
Check that the request matches the signature
Signature ok

4) Copy the certificates to the Postfix directory

# sudo cp demoCA/cacert.pem FOO-key.pem FOO-cert.pem /etc/postfix

5) Change the permissions on the files

# sudo chmod 644 /etc/postfix/FOO-cert.pem /etc/postfix/cacert.pem

# sudo chmod 400 /etc/postfix/FOO-key.pem

6) Add GMail Certificate to /etc/postfix/cacert.pem

# sudo nano /etc/postfix/cacert.pem

Paste the following at the very bottom:

-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

7) Relay your email through gmail

# sudo nano /etc/postfix/main.cf

Add: [smtp.gmail.com]:587
To: relayhost =

relayhost = [smtp.gmail.com]:587

!-Dont close the file yet, add TLS in the next step-!

8) Add TLS settings to Postfix

# sudo nano /etc/postfix/main.cf

Paste the following at the very bottom:

## TLS Settings
#
smtp_tls_CAfile = /etc/postfix/cacert.pem
smtp_tls_cert_file = /etc/postfix/FOO-cert.pem
smtp_tls_key_file = /etc/postfix/FOO-key.pem
smtp_tls_session_cache_database = btree:/var/run/smtp_tls_session_cache
smtp_use_tls = yes
smtpd_tls_CAfile = /etc/postfix/cacert.pem
smtpd_tls_cert_file = /etc/postfix/FOO-cert.pem
smtpd_tls_key_file = /etc/postfix/FOO-key.pem
smtpd_tls_received_header = yes
smtpd_tls_session_cache_database = btree:/var/run/smtpd_tls_session_cache
smtpd_use_tls = yes
tls_random_source = dev:/dev/urandom
#
## SASL Settings
# This is going in to THIS server
smtpd_sasl_auth_enable = no
# We need this
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtpd_sasl_local_domain = $myhostname
smtp_sasl_security_options = noanonymous
#smtp_sasl_security_options =
smtp_sasl_tls_security_options = noanonymous
smtpd_sasl_application_name = smtpd
transport_maps = hash:/etc/postfix/transport

!-Ok, now you can save ;)-!

9) Create a transport file

# sudo nano /etc/postfix/transport

Paste the following into the new file:

# Contents of /etc/postfix/transport
#
# This sends mail to Gmail
gmail.com smtp:[smtp.gmail.com]:587
#

10) Create the SASL password

# sudo nano /etc/postfix/sasl_passwd

Paste the following, replace username/password with your actual info:

#contents of sasl_passwd
#
[smtp.gmail.com]:587 username@gmail.com:password

11) Hash the password and transport files

# sudo postmap /etc/postfix/sasl_passwd

# sudo postmap /etc/postfix/transport

12) Reload Postfix

# sudo postfix reload

13) Restart Postfix services

# sudo /etc/init.d/postfix restart

14) Clean up the mess

# sudo rm FOO-req.pem FOO-cert.pem FOO-key.pem && sudo rm -r demoCA/

15) Send a test email

# echo "http://www.timashley.me 0wnz!!" | mail -s "Test" username@gmail.com

16) Install Apticron

# sudo apt-get install apticron

17) Configure apticron

# sudo nano /etc/apticron/apticron.conf

Enter your mail address in EMAIL=" "

18) Add Apticron to cron jobs

# crontab -e

Paste the following:

@daily /etc/cron.daily/apticron

19) System notifications

Install Webmin (Refer to "The Perfect Server" article)

You can add/remove/edit monitoring notifications in Others -> System and Server Status

Enjoy!