Unix file permissions are one of the more difficult subjects to grasp.. Well, ok maybe "grasp" isn't the word.. Master is the right word.. Unix file permissions is a hard topic to fully master, mainly I think because there aren't many instances when a computer user encounters them seriously, and bitwise is oldschool. This contains a listing of all possible permission masks and bits from a linux, php, and web hosting view.... cuz you guys AskApache Regs Rock!
Security chmod File Permissions umask
As a security nut myself, and also a Linux admin, one of my biggest pet peeves is when I've taken the time and care to segment all the users on a server into separate home directories, and then some developer comes along, logs in as root, and changes the ownership of files. Other things can cause this, like Apache, PHP, Mutt, etc.. So I've always used a cron job that executes daily (and on demand) which automatically fixes all the permissions back to what they should be.
Linux bash chmod chown cron linux permissions shell
Enumerating Permissions can be Annoying
Don’t ask me how because I won’t tell you, but on one of the hosts I was testing on that did not allow direct access I was able to get the Apache server running as dhapache to erroneously write a file into my users blog directory. This is a big security no-no and I now have my .htaccess file written into the blog directory where it should go, but instead of my php script’s user having write access to the file so I can modify it, its owned by dhapache! Because the file is owned by dhapache I shouldn’t even be allowed to know it exists, but there it is. So the next step was to try and take ownership of the .htaccess file so that I could modify it. I tried and tried but was unsuccessful, I couldn’t modify it so that was another dead end. Actually it took me awhile to figure out how to remove the file from my directory. Being that it was owned by dhapache I couldn’t delete or modify it using my php process or even through ftp/ssh! Sysadmins regularly run find commands that search the servers for any files owned by dhapache that should not be there as this is a big red flag that someone has found a way to manipulate dhapache which could potentially lead to modifying dhapache-owned server config files, which sometimes is all it takes to hack your website and server.. Luckily I was able to delete it by basically running the hack again to overwrite the file.
WordPress
Apache Web Server users have problems getting Apache Authentication/password-protection in htaccess working, this is a troubleshooting guide to get Password Protection working!
Htaccess
Apache Security tips and tricks for securing Apache Web Servers using htaccess, httpd.conf, and other built-in techniques to thwart attackers. This really should be required reading for any Apache admin or user because these little tricks are so easy to do.
Htaccess
.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 .htpasswd 301 Redirect Apache Apache HTTP Server Cache Hosting Htaccess Htaccess Software HTTP Headers httpd.conf HyperText Transfer Protocol mod_rewrite Redirect RewriteCond RewriteRule SSL
The bottom line for this article is that I want to make WordPress as fast, secure, and easy to install, run, and manage because I am using it more and more for client production sites, I will work for days in order to solve an issue so that I never have to spend time on that issue again. Time is money in this industry and that is ultimately (time) what there is to gain by tweaking WordPress.
Note: I spent no time on readability, this is primarily a read the code and figure it out article.. This is for advanced users looking for a reference or discussion and for those of you looking to advance. Feedback would be great if you make it that far..
WordPress wordpress wp-config.php
Sometimes there is an urgent need for creating an exact duplicate or "mirror" of a web site on a separate server. This could be needed for creating Round Robin Setups, Load-Balancing, Failovers, or for just plain vanilla backups. In the past I have used a lot of different methods to copy data from one server to another, including creating an archive of the whole directory and then using scp to send the file over, creating an archive and then encrypting it and then sending that file over using ftp, curl, etc., and my persistence at learning new ways to do things has paid off because now I use rsync to keep an exact replica of the entire directory on an external server, without having to use all the CPU and resources of other mirroring methods.
Security rsync ssh
- When php run as Apache Module (mod_php)
- When php run as CGI
- When cgi?d php is run with wrapper (for FastCGI)
PHP CGI Htaccess PHP php.ini
My improved version of the common printenv / test-cgi scripts for debugging Apache environment variables set in .htaccess files
Shell Scripting
Looking for some advanced uses for the shell? Here is some of my best. The shell is where 70% of my work takes place, and I have at least one terminal open almost 100% of the time, for viewing tailing color-coded logs, and of course for the SSH Tunnels that I use to route various networking through, like my email. So I decided that to standardize and create a bash_profile containing the most time-saving and helpful functions that I could use on all the various hosting environments would really be some sweet sugar, so here is my constant Work-in-progress.
It works for all shells I encounter, including BackTrack, Debian, Knoppix, Arch Linux, etc. Also works for many hosting environments I use including DreamHost, HostGator, WiredTree, and pretty much any linux VPS.
I also rely on this heavily from within shell scripts I write to access all the functions and stuff in this .bash_profile, and to do that I just do like:
#!/bin/bash
source ~/.bash_profile &>/dev/nulll
pm "PM is a function to output nice messages with color"
yn "Are you enjoying the shell" && pm "Thats great!" || pm "Perhaps you're better suited for DOS"
yn "Show Calendar" && aa_calendar
yn "Show Fortune" && aa_fortune
Linux Arch Linux bash linux shell Unix shells
NOT a typo.. 30x is measurable, well-documented, and easily tested. This is what open-source is about. I haven’t had time to post much the past year, I'm always working! So I wanted to make up for that by publishing an article on a topic that would blow your mind and be something that you could actually start using and really get some benefit out of it. This is one of those articles that the majority of web hosting companies would love to see in paperback, so they could burn it.
Optimization tmpfs
Google
This simple unix shell script automatically creates backups of a specific folder at regular hourly, nightly, weekly, and monthly intervals. Instead of the usual method for copying directory trees using tar with fifo, pipes, rsync, or NFS methods this script uses cpio which is much much faster and has cool options like saving m/a/c times, symlinks, relative paths, and weird file names.
Shell Scripting
Host Google Analytics ga.js file locally for increased speed! Makes web pages load faster.
Google
The story behind this plugin is sorta wack, but in a good way :). While doing tons of security research on permissions, authorization, access, etc.. for the Password Protection plugin (still being worked on), I needed to have unheard of debugging capabilities while working on the plugin on the various websites, webhosts, and test servers that I use to test in different environments. So I hacked together a bunch of php code that helped me debug, actually I pretty much went overkill and tried to get as much debugging info as programmatically possible, and it ended up being so much code that I took it out of my Password Protection code and made it its own plugin.
WordPress
While researching a unix/linux tool awk I came upon one of the most thorough and helpful tutorials I've ever seen devoted to a particular topic. It's old-school just the way I like it. I contacted the author, Bruce Barnett because I just HAD to have this article for my readers, who are predominantly running solaris/unix/bsd/linux and he kindly gave permission.
Linux
A souped-up version of the Apache printenv script for hard-core server environment debuggery.
#!/bin/sh
echo -e "Content-type: text/plainnn"
...
__T "CURRENT PROCESS CMDLINE"
{
for p in `echo /proc/[0-9]*/cmdline`;
do
pid=${p:6:$((${#p}-13))}
[[ $pid == $PPID || $pid == $$ ]] && continue;
__M "[ /proc/$pid ]";
sed 's/x00/ /g;G' $p 2>/dev/null
done
}
fi Hosting Apache HTTP Server Apache server CGI Common Gateway Interface Htaccess
Ever wanted to execute commands on your server through php? Now you can. I'm calling this file (see below) shell.php and it allows you to run commands on your web server with the same permissions that your php executable has.
Hacking AJAX PHP
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 centos compression InnoDB lz4 MariaDB MySQL
