Related to Certificates

Generate a CSR
https://www.digitalocean.com/community/questions/how-do-i-generate-a-csr-key

Create the self-signed certificate
https://help.ubuntu.com/lts/serverguide/certificates-and-security.html

Create thrid certificate using CSR
https://ssl.comodo.com/free-ssl-certificate.php
https://support.comodo.com/index.php?/comodo/Knowledgebase/Article/View/637/66/

Aditional information
https://www.ssl2buy.com/ssl-certificate-google-rankings
https://www.elegantthemes.com/blog/tips-tricks/how-to-get-a-free-ssl-certificate-and-why-google-is-forcing-you-to

Ubuntu 14 install sSMTP

Ubuntu
1.1) Install sSMTP

$sudo apt-get install ssmtp
$sudo vi /etc/ssmtp/ssmtp.conf  #add or set

root=username@gmail.com
mailhub=smtp.gmail.com:587
rewriteDomain=
hostname=fileserver.local
UseSTARTTLS=YES
AuthUser=username
AuthPass=password
FromLineOverride=YES
sudo vi /etc/ssmtp/revaliases
root:username@gmail.com:smtp.gmail.com:587
youruser:username@gmail.com:smtp.gmail.com:587

1.2) How to use

$ssmtp recipient_email@example.com  #sSMTP will then wait for:
To: recipient_email@example.com
From: myemailaddress@gmail.com
Subject: test email

hello world!
#press Ctrl-D for send the message before closing.

$ssmtp myemailaddress@gmail.com < msg.txt

To: myemailaddress@gmail.com
From: myemailaddress@gmail.com
Subject: alert

The server is down!

1.3) Alternative to use

$sudo apt-get install heirloom-mailx -y
$echo testing|mail -s 'Test Mail' Insert email address to send to here


References:
[1]  http://tombuntu.com/index.php/2008/10/21/sending-email-from-your-system-with-ssmtp/

Fedora/CentOs
[2.1] postfix https://kifarunix.com/configure-postfix-as-send-only-smtp-server-on-fedora-29/
[2.2] sendmail https://tecadmin.net/install-sendmail-on-fedora/

Mono Develop on Ubuntu 14

#monodevelop 4

sudo apt-get install monodevelop

#upgrade to monodevelop 5

sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
echo "deb http://download.mono-project.com/repo/debian wheezy main" | sudo tee /etc/apt/sources.list.d/mono-xamarin.list
sudo apt-get update
sudo apt-get install monodevelop

References:

[1] Monodevelop versions https://download.mono-project.com/archive/