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MariaDB with LZ4 Compression Howto for CentOS

I really really wanted to run the latest MariaDB with LZ4 Page Compression.. it is a game changer for many types of large databases I deal with. So I compiled it manually in a way that is repeatable and follows best-practices and it's now powering this site. Now I can use InnoDB Page Compression with lzo, lzma, bzip2, snappy, or my favorite algorithm: LZ4.

Thought this would be a good chance to post a howto, and show that there is a lot you can do by compiling software yourself and breaking the package management one-click install shackles.

Linux, MySQL

Building strace-plus

strace-plusstrace+ is an improved version of strace that collects stack traces associated with each system call. Since system calls require an expensive user-kernel context switch, they are often sources of performance bottlenecks. strace+ allows programmers to do more detailed system call profiling and determine, say, which call sites led to costly syscalls and thus have potential for optimization.

Linux

.htaccess Plugin Blocks Spam, Hackers, and Password Protects Blog

.htaccess security plugin 2

Well what can I say, other than this is sooo DOPE! Here is a list of the modules this plugin (version 4.7 unreleased) will automatically detect. I compiled the list myself using every module included with any default Apache installation for ALL the versions listed below, 1.3 to 2.2+

Want to know something else I'm including in this plugin? For each and every module that is detected, this plugin can then detect ALL of the modules .htaccess Directives! For instance, RewriteRule, AccessFileName, AddHandler, etc.. are each a directive belonging to a module that is allowed to be used from within .htaccess files.

Talk about sick.. these tricks have the diamond disease!

WordPress

THE Ultimate Htaccess

htaccess file .htaccess is a very ancient configuration file for web servers, and is one of the most powerful configuration files most webmasters will ever come across. This htaccess guide shows off the very best of the best htaccess tricks and code snippets from hackers and server administrators.

You've come to the right place if you are looking to acquire mad skills for using .htaccess files!

Apache, Hosting, Htaccess, Optimization, Security, SEO, Web Development, WordPress

Hacking VLAN switched networks

Bypassing VLAN security on networked switchesThere isn't much vlan info on the net in terms of specifics and I had to learn all about it because I needed to log in to a switch that was on a different vlan. With the help of the Ettercap developers NaGA and ALoR I figured it out.

Originally Posted: 3/30/2004

Hacking

View all MySQL Variables for Pasting into my.cnf

mysql-variables-my-cnf-fileThis is really useful for me because I work with dozens of different database servers. The first thing I do is run this command and paste it into the servers /etc/my.cnf file. That way I will always know the original value and it just makes life much easier.

$ mysql -NBe 'SHOW VARIABLES' |sed 's,\t,^=,'|column -ts^|tr "\n" '@'|eval $(echo "sed '" "s,@\("{a..z}"\),\n\n\1,;" "'")|tr '@' "\n"|sed 's,^,# ,g'

MySQL

Debugging Tools for Windows

I am almost ready to publish the final tutorial on using ssh tunnels from a truecrypt partition on a Windows machine. Of course I choose to go way overboard in my research and the tutorial is full of some pretty awesome windows tricks.. I will come back to this post soon and post all the other advanced tools I use for debugging windows, for now though you MUST know how to debug the kernel and use these basic debugging tools.

Windows

Linux Debugging using a Bootloader with Kernel Parameters

grub awesomeAs an example, here is the boot line that I am using at the moment on an older Dell Desktop, just to illustrate module parameters and environment vars. 

title  Arch Linux X-256
linux   /vmlinuz-linux root=UUID rw rootfstype=ext4 elevator=noop selinux=0 plymouth.enable=0 raid=noautodetect ipv6.disable=1 video=DP1:d rcutree.rcu_idle_gp_delay=1 i915.panel_ignore_lid=-1 i915.modeset=1 TERM=rxvt-256color

Linux

Notes from Apache HTTPD Source Code

thought I'd take a break from coding and post about how open-source is such a great tool for finding the best answers to the toughest questions,

/** is the status code informational */
#define ap_is_HTTP_INFO(x)         (((x) >= 100)&&((x) < 200))
/** is the status code OK ?*/

#define ap_is_HTTP_SUCCESS(x)      (((x) >= 200)&&((x) < 300))
/** is the status code a redirect */
#define ap_is_HTTP_REDIRECT(x)     (((x) >= 300)&&((x) < 400))

/** is the status code a error (client or server) */
#define ap_is_HTTP_ERROR(x)        (((x) >= 400)&&((x) < 600))
/** is the status code a client error  */

#define ap_is_HTTP_CLIENT_ERROR(x) (((x) >= 400)&&((x) < 500))
/** is the status code a server error  */
#define ap_is_HTTP_SERVER_ERROR(x) (((x) >= 500)&&((x) < 600))

/** is the status code a (potentially) valid response code?  */
#define ap_is_HTTP_VALID_RESPONSE(x) (((x) >= 100)&&((x) < 600))

Hacking

Install multiple OS Without Cds

Orig published 2006. I had a CD-RW drive but being a computer security researcher I had no money for blank cd-recordables. What follows is how I managed to install various operating systems on my computer (1 hard drive) without having to burn to a CD the ISO and then boot from that.

And also:

==Phrack Inc.==
 
              Volume 0x0b, Issue 0x3f, Phile #0x0a of 0x14
 
|=-----------------=[ Hacking Grub for fun and profit ]=-----------------=|

Linux

Internet Census 2012 – Port scanning using insecure embedded devices – Carna Botnet

While playing around with the Nmap Scripting Engine (NSE) we discovered an amazing number of open embedded devices on the Internet. Many of them are based on Linux and allow login to standard BusyBox with empty or default credentials. We used these devices to build a distributed port scanner to scan all IPv4 addresses. These scans include service probes for the most common ports, ICMP ping, reverse DNS and SYN scans. We analyzed some of the data to get an estimation of the IP address usage.

Hacking

HOWTO: Uninstall CPANEL over SSH

The following is just a quick but detailed reference of some of the commands I used to successfully uninstall cpanel permanently. This is for advanced users of the shell. If you run a single one of these commands without fully understanding it, you will probably kill your server, lose everything on it permanently, not have a website or email for weeks.. So backup everything. FIRST. You should also contact your hosting provider support - but be prepared for some MAJOR negativity.. cpanel makes things very easy for web-hosting companies, and you are less than a drop in their bucket.

Hacking

Actual Htaccess Files from My Server

#### No https except to wp-admin -
# If the request is empty ( implies fopen or normal file access by a php script )
RewriteCond %{THE_REQUEST} ^$ [OR]

# OR if the request if for wp-admin or wp-login.php
RewriteCond %{REQUEST_URI} ^/(wp-admin|wp-login.php).*$ [NC,OR]

# OR if the Referer is https
RewriteCond %{HTTP_REFERER} ^https://www.askapache.com/.*$ [NC]

# THEN skip the following rule, basically all this does is force https or badhost to be redirected
# BUT because of the above 3 rewritecond's, this won't break poorly written admin scripts
RewriteRule .* - [S=1]

RewriteCond %{HTTPS} =on [OR]
RewriteCond %{HTTP_HOST} !^www.askapache.com$ [NC]
RewriteRule .* https://www.askapache.com%{REQUEST_URI} [R=301,L]

RewriteCond %{THE_REQUEST} ^[A-Z]{3,9} /(wp-admin/.*|wp-login.php.*) HTTP/ [NC]
RewriteCond %{HTTPS} !=on
RewriteRule .* https://%{SERVER_NAME}%{REQUEST_URI} [R=301,L]

Htaccess

PortaPutty Auto-Reconnecting SSH Tunnels on an Encrypted TrueCrypt Portable USB Key w GPG

Ok I just came back up to write the intro.. I'm trying to keep it short to avoid getting bogged down by the coolness of each step. Here is what goes on. When I logon to my XP machine at work, I bring my usb key and plug it in first. On logging a window pops up first and it's a password prompt to mount my encrypted drive leonardo. It also checks a keyfile that is located on my usb key, but all I do now is type in my password. That causes my encrypted folder to be accessible to me like a normal drive, and it autoruns a startup batch file.

The batch file causes Portable versions of Firefox (all my bookmarks, my settings) to load, and launches Portable Mozilla Thunderbird (IMAP makes this work well), which is my favorite program (great GPG features and open-source!). Also Some Adobe CS4 software is loaded from the hard drive, like DreamWeaver. In the background, a service we created executes a PortaPuttY plink command to create forwarded tunnels from various remote servers and accounts, all using key-based encryption. These tunnels are automatically reconnected if they are disconnected, meaning you can use a socks 5 if you want or even better!

Hacking

Optimizing Servers and Processes for Speed with ionice, nice, ulimit

To prepare for several upcoming articles on AskApache that are focused on optimizing Servers and Sites from a server admin level, here is an article to introduce the main tools that we will be using. These tools are used to optimize CPU time for each process using nice and renice, and other tools like ionice are used to optimize the Disk IO, or Disk speed / Disk traffic for each process. Then you can make sure your mysqld and httpd processes are always fast and prioritized.

Optimization

DNS Round Robin Configuration using Rsync over SSH

The goal is to add the HostGator server to be an exact mirror of the s.askapache.net domain, then to add that server as a 2nd A record to my DNS zone. That way half the visitors to the size will be taking up resources and bandwidth on the HostGator server instead of mine.

Round Robin A records in DNS are intended to evenly distribute queries between each host of the same name. Using some tricks straight out of a hackers toolbox we can verify if the distribution is taking place. (It is.)

Optimization

Upgrading to DreamHost Private Servers

DreamHost PS gives you your own "virtual machine", protecting your CPU and RAM on your physical machine for faster websites. Here's what I like and dislike about DreamHostPS, and some of the issues and solutions for migrating.

Hosting

The Latest and Greatest php.ini

Grab the latest php.ini developmental version and discover new or previously hidden php runtime configuration settings... ahead of everyone else!

PHP

Story by Author of PING for UNIX

Yes, it's true! I'm the author of ping for UNIX. Ping is a little thousand-line hack that I wrote in an evening which practically everyone seems to know about. :-)

Hacking

Caching Tutorial for Webmasters

If you examine the preferences dialog of any modern Web browser (like Internet Explorer, Safari or Mozilla), you'll probably notice a 'cache' setting. This lets you set aside a section of your computer's hard disk to store representations that you've seen, just for you. The browser cache works according to fairly simple rules. It will check to make sure that the representations are fresh, usually once a session (that is, the once in the current invocation of the browser).

Optimization