Databases, Systems & Networks

Source: ResponsiveMind

La réplication d’un base de données permet de disposer du même jeu de données à tout moment sur deux serveurs ou plus. MySQL permet d’automatiser la recopie des données entre une machine principale et plusieurs secondaires de façon unidirectionnelle (réplication master-slave) ou de façon bidirectionnelle entre 2 serveurs (réplication master-master). Dans ce tutoriel, nous allons mettre en place ces deux types de systèmes, le second étant une extension du premier.

Si vous n’avez pas lu mon article à propos de la création d’une architecture serveurs distribuée, je vous invite à le faire, et spécialement mon exemple de mise en en oeuvre avec 2 serveurs, vous comprendrez peut-être mieux l’utilité d’une configuration de ce type. Pour les plus pressées, sachez simplement que je proposais de créer 2 serveurs web accueillant chacun sa propre base de données, les données étant strictement identiques et chaque insertion ou modification de données étant immédiatement recopiée. Lire la suite…

POSIX Access Control Lists (ACLs) are more fine-grained access rights for files and directories. An ACL consists of entries specifying access permissions on an associated object. ACLs can be configured per user, per group or via the effective rights mask.

These permissions apply to an individual user or a group, and use the same as rwxfound in regular permissions.

For an explanation of rwx, see FilePermissions

Enabling ACLs in the Filesystem

Before beginning to work with ACLs the file system must be mounted with ACLs turned on. This can be done in /etc/fstab for the changes to be permanent.

Lire la suite…

Plug-ins

Our job as WordPress users (aside from contributing to the WordPress community) is keeping our installs safe from people we do not want to access our sites. There are numerous plug-ins to help shore up our WordPress defenses such as Login LockDown which records IP address and blocks them after a set number of login attempts which helps against brute force attacks. Lire la suite…

source: fail2ban.org

Using geolocation to locate your attackers.

I use fail2ban on my servers to protect them from would-be attackers, if you don’t your either insanely nieve to the fact that somebody wants in your system, or your just wanting to see if you can get hacked. Most of the attackers I would assume are just after another « bot » in their « net », or maybe a place to host files.

Durzo hosts a script that allows you to log the attacks on you into a mysql database with geocoding, I thought this would be cool to use as I could see from where I was being attacked. I then got this working and another script to display the table in a web page so I could view the data easily.

I then found some scripts from Google to pull data from MySQL in a geolocation table and generate an XML file used to import into Google Maps. With some tweaking and customizing, I now have a map with the geolocation data as markers on the map. Not all the markers are right on a building, but they are close enough for me to see the areas from which attacks are coming.

Now on to the good stuff… Lire la suite…

Saving iptables rules for reboot

On a server, iptables rules don’t reload automatically at reboot. You need to reload the rules using ax executable shell scripture a dedicated utility that will load them at the same time as the program itself, i.e. with the kernel.

Depending of the version of Linux you use, you can select different methods:

sudo su
iptables-save > /etc/iptables.rules

In /etc/network/if-pre-up.d/iptables, put:

#!/bin/sh
iptables-restore < /etc/iptables.rules
exit 0

After, in /etc/network/if-post-down.d/iptables, put:

#!/bin/sh
iptables-save -c > /etc/iptables.rules
if [ -f /etc/iptables.rules ];
       then iptables-restore < /etc/iptables.rules
fi
exit 0

After, give permission to the scripts:

sudo chmod +x /etc/network/if-post-down.d/iptables sudo chmod +x /etc/network/if-pre-up.d/iptables

Another scenario is to is to install iptables-persistent:

sudo apt-get install iptables-persistent

After it’s installed, you can save/reload iptables rules anytime:

    sudo /etc/init.d/iptables-persistent save 
    sudo /etc/init.d/iptables-persistent reload

Or if you use Ubuntu server 16.04, things are simpler:

    sudo netfilter-persistent save
    sudo netfilter-persistent reload