How To Secure MySQL Replication Using SSH

https://www.digitalocean.com/community/tutorials/how-to-secure-mysql-replication-using-ssh-on-a-vps

http://makandracards.com/makandra/573-mysql-replication-how-to

http://www.somacon.com/p567.php


Bi-directional SSH tunnel

local$: ssh -N -R 33061:localhost:3306 remote_host_ip

remote$: ssh -p 33061 localhost


Create/restore a slave using GTID replication
https://www.percona.com/blog/2013/02/08/how-to-createrestore-a-slave-using-gtid-replication-in-mysql-5-6/


MySQL Multi-Source Replication
http://www.xenialab.it/meo/web/white/oracle/myrepl_multi.htm

If we have a chain of slaves, it's important to enable slave update logging, on config file:
log-slave-updates = 1

Unable to install Certbot

Error on installing Certbot for Lets Encrypt

# apt-get install -t jessie-backports certbot python-certbot-apache Reading package lists... Done E: The value 'jessie-backports' is invalid for APT::Default-Release as such a release is not available in the sources

Solution:
You should first enable backports, see https://backports.debian.org/Instructions
http://guide.debianizzati.org/index.php/Il_repository_Backports