Category Archives: Linux

Kodibuntu and TL-WN822N v3 wireless fix

I have a Zotac MAG HD-ND01-U I bought almost 5 years ago that I use to play movies for the family. Even at the time I bought it, the Zotac was very low end; it ships with an Intel Atom N330 CPU, Nvidia ION GPU, 160GB 5400RPM HDD and 2GB of RAM. It has been since upgraded to a 500GB 7200rpm HDD and 4GB of RAM. Previously I was just running Win7 and using MPC-HC to play movies on the big screen. The Zotac was just barely capable of playing 1080p x264 mkvs with that combination; CPU usage was still very high despite using hardware acceleration in LAV Video Decoder. It was also really annoying waiting for Windows processes (TrustedInstaller.exe and svchost.exe) to stop eating CPU cycles after boot up. I decided it was time to take look at Kodi; a software media center formerly known as XBMC. I made a Live USB of Kodibuntu and spent a couple hours just trying to get it to find my movie library over the network; when I finally got a movie to play, it played perfectly with no jitter and very low CPU usage. If anyone out there is wondering if an Intel Atom and Nvidia ION are enough to play 1080p x264 mkvs, I can assure you it will play perfectly under Kodibuntu. However it will struggle with mkvs encoded in 10bit.

After the successful trial of the Live USB, I rebooted and performed the full installation thinking that maybe the network issue was just the Live USB environment. After the full install, I tried installing updates and the network would stop working after a few minutes. I did some searching online and apparently the driver that ships with Ubuntu based distributions doesn’t work properly with the TL-WN822N v3 USB wireless adapter I was using. I found the solution here via this page of the Ubuntu Community Help Wiki. I’ve included all the commands from the solution below; they will install a patched driver and remove the native one.

ownCloud 8 on CentOS 6.6 using Nginx and PHP-FPM

Earlier this week I decided to test drive ownCloud; an open source alternative to cloud sync services like Google Drive or Dropbox. The main difference is that you install and run ownCloud on your own server.

ownCloud provides packages for most Linux distributions including CentOS here; the advantage of installing from the package is that it will automatically install required dependencies and you can  update ownCloud with yum. If you use the ownCloud package, you will also need Remi’s RPM repository as CentOS 6 provides PHP 5.3 and ownCloud 8 requires PHP 5.4.

Since I already had a server running Nginx I decided to skip the package installation of ownCloud because it also installs Apache as a dependency. The steps below can be used to set up ownCloud 8 on CentOS using Nginx, PHP-FPM and MySQL.

Set up Nginx and Remi repos:

Install Nginx, MySQL and PHP components:

Start MySQL and run mysql_secure_installation script to create root password (answer Y to all questions):

Now create the database and user for ownCloud:

Create document root for Nginx and install ownCloud:

Edit /etc/php-fpm.d/www.conf to replace apache user with nginx on lines 39 and 41:

Give nginx user permissions on /var/lib/php/session (this fixed a redirect loop I was getting when trying to login):

Make sure services start automatically on boot:

Now you just need to configure Nginx to work with ownCloud; below is my configuration file that I made based on the ownCloud documentation here.

Once you have Nginx configured correctly, browse to your server and you will be greeted by the following screen where you will create the admin account and provide the details of the MySQL database you created earlier:

ownCloud_setup_page

For added security, you can configure Fail2Ban to protect the ownCloud login page from brute force attempts by using the guide located here: http://www.tech-and-dev.com/2014/11/protecting-owncloud-against-bruteforce-attacks-with-fail2ban.html

CentOS MotD Generator

Recently a friend of mine showed me the cool MotD message he set up on his Ubuntu server that displays upon ssh login; it displays useful information such as OS & kernel version, uptime, system load, memory usage and other system stats. After some searching I found a MotD generator for CentOS here; it’s made up of two scripts: count_yum_updates.sh and generate_motd.sh. As the names imply, the first script counts the number of yum updates available, whose output will be read by the second script when it creates the MotD banner. Below are the instructions I’ve adapted from the author’s site on how to install it.

Install the dependencies for the scripts:

Download the scripts and make them executable:

Test the scripts to see if they work correctly:

If everything works, you should see similar output to below:

centos_motd

Copy scripts to their final locations:

Make a cron job to run count_yum_updates.sh automatically (adjust for your own preferred interval):

Now you’ll get a nice MotD whenever you log in with ssh. These scripts worked perfectly fine on a CentOS droplet at Digital Ocean but at RamNode the MotD did not display the IP address of the server. I’m not sure if it was because they were OpenVZ or not but I fixed the issue by modifying line 80 of generate_motd.sh:

Original line 80:

Modified:

Protect WordPress Login using Fail2Ban and Cloudflare

I’ve discovered a way to protect my WordPress site from brute force attacks thanks to these two guides I found:

DDOS PROTECTION WITH CLOUDFLARE AND FAIL2BAN
WordPress Login Security with Fail2Ban

The best part is these guides do not require installing yet another plugin to WordPress. If your WordPress site does not sit behind Cloudflare, you can just follow the second guide; if you are using Cloudflare however, that guide won’t do anything for you because iptables will only ever see IP addresses from Cloudflare, not your attacker. To make it work with Cloudflare, we need the action filter created in the first guide.

The following steps are a combination of the two guides above and are what I used to configure fail2ban to ban IPs at Cloudflare after failed logins on WordPress; if you haven’t done so already you need to install mod_cloudflare for Apache so it can see the IPs of visitors instead of Cloudflare’s. It’s also a good idea to configure iptables to only allow HTTP/HTTPS traffic from Cloudflare so they can’t bypass it and browse your site directly; the list of Cloudflare IPs is available here as a text file.

First we need to make WordPress log failed authentication attempts; edit the functions.php of your site’s theme and add the following:

Next we need edit /etc/rsyslog.conf and add the following lines under the “Rules” section:

Since we’ve added a new log, we should configure logrotate; add the following to the bottom of /etc/logrotate.conf:

Restart rsyslog with:

Next we create the filter for fail2ban to use; create a new file /etc/fail2ban/filter.d/wordpress.conf with the following contents:

Now we define the action for fail2ban to use; create a new file /etc/fail2ban/action.d/cloudflare.conf with the contents below. Remember to insert your Cloudflare email address and API Key at the bottom.

Now that we have the filter and action created for fail2ban we can add the jail to /etc/fail2ban/jail.local:

Restart fail2ban and it will watch /var/log/wp_f2b.log for failed WordPress authentication and use the Cloudflare API to ban/unban IPs.

Nginx Reverse Proxy with Deluge Web UI

Last year I experimented with using a seedbox for torrenting; I built one using CentOS and Deluge and took a snapshot before I decided to stop using it. Recently I tried deploying it again from the snapshot and found the Deluge Web UI unreachable as Chrome displayed the error message ERR_SSL_VERSION_OR_CIPHER_MISMATCH. It appears in the time since I built it, browsers have stopped supporting SSLv3 due to the POODLE vulnerability. According to this thread, it can be fixed by updating to a newer version of Deluge; however I needed to keep using version 1.3.6 because reasons. Fortunately I was able to configure Nginx as a reverse proxy with SSL enabled for the Deluge Web UI; instead of connecting to the Deluge Web UI directly, I can connect to it through Nginx over HTTPS while the Web UI continues to listen on localhost:8112. Nginx is easy to install and there are many guides on the internet; here’s one for Ubuntu 14.04 and one for CentOS 6.

Below is my configuration for proxying Deluge Web UI through Nginx with SSL enabled; I found the SSL cipher settings on a blog post about hardening SSL ciphers here and the proxy settings on the Deluge Bug Tracker here.