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Hide Server and Web Application Information

First and foremost, this is security over obscurity. No relevant security improvement is gained by this, but rather just annoy or hopefully prevent automated bots or script kiddies from doing any future damage. By NO means it should be the only defensive mechanism for any site!

This site runs on Drupal. Drupal, by default returns Drupal specific http headers on every request. So I wanted to disabled this completely at the server level, in addition to the PHP and Apache information that is part of a typical stock LAMP configuration.

First, we start with PHP. The PHP X-Powered-By header can be disabled by disabling the expose_php option:

expose_php = Off

Next, is updating the default Server header set by Apache:

ServerTokens Prod

Finally, it's time to remove the X-Generator and X-Drupal-Cache specific Drupal headers.
Using Apache via mod_headers module:

<IfModule mod_headers.c>
     Header unset X-Generator
     Header unset X-Drupal-Cache

Using Nginx via the headers more module:

more_clear_headers 'x-generator';
more_clear_headers 'x-drupal-cache';

Why stop here when I can set custom headers. So as a joke, I want to tell the world that my sites are powered by Unicors and I’m the hacker being it. Doing so is dead simple.


add_header              X-Powered-By "Unicorns";
add_header              X-hacker "Alpha01";

Varnish (vcl_deliver)

set resp.http.X-Powered-By = "Unicorns";
set resp.http.X-hacker = "Alpha01";

Now, let's view my new http headers

alpha03:~ tony$ curl -I
HTTP/1.1 200 OK
Date: Thu, 24 Nov 2016 03:53:40 GMT
Content-Type: text/html; charset=utf-8
Connection: keep-alive
Set-Cookie: __cfduid=d8fbf8e2a27fac74e782224db3fd3c86c1479959620; expires=Fri, 24-Nov-17 03:53:40 GMT; path=/;; HttpOnly
Strict-Transport-Security: max-age=63072000; includeSubdomains; preload
Expires: Sun, 19 Nov 1978 05:00:00 GMT
Cache-Control: public, max-age=300
X-Content-Type-Options: nosniff
Content-Language: en
X-Frame-Options: SAMEORIGIN
Last-Modified: Tue, 22 Nov 2016 06:55:27 GMT
Vary: Cookie,Accept-Encoding
Front-End-Https: on
X-Powered-By: Unicorns
X-hacker: Alpha01
Server: cloudflare-nginx
CF-RAY: 3069ea499a6320ba-LAX



Awesome Applications: 

Running my own Git server: GitList

For the longest time I've been wanting to streamline updates to my sites, ie. implement good software deployment technique and procedures. To be specific, start using Git for source code management, and Jenkins to deploy. No, I'm not drinking the whole Agile Kool-Aid. After all we're in 2015, and people who still continue to use FTP/SFTP to push out changes to their sites should really need to be practicing more long term sustainable procedures. Setting up a git server is really simple. See

Git workflow:
I prefer to only communicate with Git over ssh and not https. Since I don't use the default ssh port, the initial repository clone looks like this:

git clone ssh://$GIT-USER@$GIT-SERVER:$SSH-PORT/home/git/$REPO

GitHub has become the defacto Git hosting provider. I think much of it's success, aside from the fact that Git is an amazing piece of software, is GitHub's polished web user interface. While Git ships with a daemon that provides a visual look at the repositories, it's definitely not pretty. I wanted to have a local GitHub like interface on my private git repos, so I decided to use GitList. GitList is fairly minimalistic. Requiring just PHP and mod_rewrite, it allows you to browse your repositories, view files under different revisions, commit history and diffs. Configuring GitList is really easy.

git clone
cd gitlist
chmod 777 cache
mv config.ini-example config.ini

Then update config.ini to point to the location where the Git repositories are stored in the server. On my server, they're located in /home/git.

repositories[] = '/home/git/' ;

Lastly, is just configuring the web server's virtual host. Since I use Apache mine looks like this.


        DocumentRoot /var/www/gitlist

        <Directory "/var/www/gitlist">
                AllowOverride All
                AuthType Basic
                AuthName "Git Repos"
                AuthUserFile /home/svn/.htpasswd
                Require valid-user

        SSLEngine on
        SSLCertificateFile /etc/httpd/certs/
        SSLCertificateKeyFile /etc/httpd/certs/
        SSLCACertificateFile /etc/httpd/certs/rubyninjaCA.crt

        ErrorLog logs/git_ssl_error_log
        CustomLog logs/git_ssl_request_log \
                "%t %h %{SSL_PROTOCOL}x %{SSL_CIPHER}x \"%r\" %b"



Awesome Applications: 

Server Move and Upgrades!

My little corner of the internet has a new home. My old $29.99 8GB RAM, 3.40GHz Intel Core i3 dedicated server was simply not enough to handle my server needs. Which apparently OVH doesn't even provide that service anymore. So instead I hoped to their mid-tear dedicated service service branch they call So you Start. I opted with their $49.00 SYS-IP-2 service. Now my server's specs is a follows:

  • 2.66 GHz+ Intel Xeon W3520 (4 cores/ 8 threads)
  • 32 GB ECC
  • 2 x 2 TB SATA drives (Software RAID)

I would've love the drives to be SAS and the RAID to be hardware based, but it's definitely not a deal breaker, and just $49.99 a month, it's not much to complain about.

CentOS 6 to CentOS 7 upgrade:
My server migration was fairly straight forward for the most part. I opted to re-create the KVM hypervisor and its guests from scratch. Mainly because I wanted to upgrade all of guests and host from CentOS 6 to CentOS 7. This is where I encountered my first problem. Since I rely on custom nat PREROUTING/POSTROUTING iptables firewall rules for my VMs to properly be able to talk to each other and to the internet. I realized CentOS 7 defaults to firewalld, so instead of trying to rewrite my firewall rules to be compatible with firewalld, I decided to continue to use CentOS 6 on my host operating system, and only upgrade my guests VMs to CentOS 7.

On a side note, my previous guest VMs were originally using raw image format (default cache settings) for its storage, and by god what a hell of a difference it makes changing to use native block storage via LVM. I/O performance on my old server was terrible, the I/O wait percentage was roughly about 6%, now it's less than 1%. Even with the software raid, I/O performance is much better on my new server.

PHP 5.3 to 5.6 upgrade:
Since I don't have anything heavily customized on any of sites, the PHP version upgrade was practically painless.

Apache 2.2 to 2.4 upgrade:
Luckily, upgrading Apache wasn't a big hassle. Anyone considering upgrading from 2.2 to 2.4, it's definitely worth checking out the official upgrade documentation since dropping the old 2.2 configs in onto a 2.4 environment won't work off the gecko. In my case all of my sites were returning 403 forbidden replies and non of my .htaccess files weren't being read by Apache. The fix was really simple.

                AllowOverride All
                Require all granted

I must say, I really like Apache 2.4 new authorization syntax. What used to be a three line configuration is now a single line configuration, and much more human readable.

Future Upgrade Plans:
I didn't tackle this during the server migration, but I'll definitely going to be upgrading to Varnish 4 and use PHP FastCGI via php-fpm and mod_proxy_fcgi.



Awesome Applications: 

CentOS: Apache - Directory index forbidden by Options directive

By default, the CentOS Apache configuration does not allow index directory listings. So I enabled Indexes Option's for the directory that I wanted allow this feature within my custom vhost . To my surprise after I made the Apache config update, directory listing was not working and I was still getting the default CentOS Apache welcome page.

Apache error log:

[Sat Apr 26 14:42:11 2014] [error] [client] Directory index forbidden by Options directive: /www/mysecureshit/

It turns out the default /etc/httpd/conf.d/welcome.conf file option overrides the +Indexing Options that I explicity enabled within my custom vhost.

# This configuration file enables the default "Welcome"
# page if there is no default index page present for
# the root URL.  To disable the Welcome page, comment
# out all the lines below.

    Options -Indexes
    ErrorDocument 403 /error/noindex.html

The fix was to simply disable welcome.conf.


Awesome Applications: 

Varnish WordPress Performance Testing

Thanks to my new job, I've been working a lot with Varnish. Man, Varnish is one kick ass HTTP web accelerator! A few months back I ran a few performance Apache performance tests on my WordPress site with different layers of caching enabled:

So now I wanted to see how the results may differ using Varnish.

At a bare minimal, Varnish needs to be configured to remove cookies set by WordPress in order to make the content cacheable.

sub vcl_recv {
  # Drop any cookies sent to Wordpress.
  if (!(req.url ~ "wp-(login|admin)") && ~ "") {
    unset req.http.cookie;

sub vcl_fetch {
  # Drop any cookies Wordpress tries to send back to the client.
  if (!(req.url ~ "wp-(login|admin)") && ~ "") {
    unset beresp.http.set-cookie;

With this configuration enabled, I ran the same identical ab tests that used to benchmark my server previously.

[[email protected] ~]# ab -n 1000 -c 5
This is ApacheBench, Version 2.0.40-dev <$Revision: 1.146 $> apache-2.0
Copyright 1996 Adam Twiss, Zeus Technology Ltd,
Copyright 2006 The Apache Software Foundation,

Benchmarking (be patient)
Completed 100 requests
Completed 200 requests
Completed 300 requests
Completed 400 requests
Completed 500 requests
Completed 600 requests
Completed 700 requests
Completed 800 requests
Completed 900 requests
Finished 1000 requests

Server Software: Apache/2.2.15
Server Hostname:
Server Port: 80

Document Path: /index.php
Document Length: 0 bytes

Concurrency Level: 5
Time taken for tests: 39.528015 seconds
Complete requests: 1000
Failed requests: 0
Write errors: 0
Non-2xx responses: 1001
Total transferred: 374139 bytes
HTML transferred: 0 bytes
Requests per second: 25.30 [#/sec] (mean)
Time per request: 197.640 [ms] (mean)
Time per request: 39.528 [ms] (mean, across all concurrent requests)
Transfer rate: 9.23 [Kbytes/sec] received

Connection Times (ms)
min mean[+/-sd] median max
Connect: 87 100 134.1 93 3092
Processing: 88 95 10.7 91 220
Waiting: 87 94 10.6 90 218
Total: 177 196 134.4 186 3183

Percentage of the requests served within a certain time (ms)
50% 186
66% 192
75% 196
80% 199
90% 207
95% 217
98% 234
99% 251
100% 3183 (longest request)

The requests per second handled by the webserver weren't much different from the caching layer that I already had enabled previously, which is the WordPress W3 Total Cache plugin configured with Page, Database, Object, and Browser cache enabled using APC, and mod_pagespeed.

However the huge difference is that all requests never reached the Apache backend. Varnish cached all content and served all the requests directly. Varnish is just fucking awesome.

Awesome Applications: 

PHP: XCache performance testing

Aside APC, as far as I know XCache is the second most popular PHP caching optimizer. So I manually compiled and installed XCache on my VM and configured the WordPress W3 Total Cache plugin to use the XCache optimizer and ran the same benchmarks test that I did when APC was enabled.

After a few tests, the total requests per second was around 24-25 seconds. Slightly slower than APC. However, unlike APC, I noticed that with XCache the overall server load was less (peak at about 3.3), in addition the I/O system activity also appeared to be less than with APC.

Concurrency Level: 5
Time taken for tests: 40.740110 seconds
Complete requests: 1000
Failed requests: 0
Write errors: 0
Non-2xx responses: 1000
Total transferred: 351000 bytes
HTML transferred: 0 bytes
Requests per second: 24.55 [#/sec] (mean)
Time per request: 203.701 [ms] (mean)
Time per request: 40.740 [ms] (mean, across all concurrent requests)
Transfer rate: 8.39 [Kbytes/sec] received

Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 6 134.1 0 3000
Processing: 99 196 25.6 200 297
Waiting: 98 196 25.6 199 297
Total: 99 202 136.9 200 3209

Percentage of the requests served within a certain time (ms)
50% 200
66% 209
75% 214
80% 216
90% 222
95% 227
98% 234
99% 241
100% 3209 (longest request)


Awesome Applications: 

Apache stress testing

As I didn't have anything much better to do a Sunday afternoon, I wanted to get some benchmarks on my Apache VM that's hosting my blog I've used the ab Apache benchmarking utility in the past to simulate high load on a server but have not used it on benchmarking Apache in detail.

My VM has a single shared Core i5-2415M 2.30GHz CPU with 1.5 GB of RAM allocated to it.

I based made my benchmarks using a total of 1000 requests with 5 concurrent requests at a time.

ab -n 1000 -c 5

Using just the mod_pagespeed Apache module enabled.

Time taken for tests: 154.687976 seconds
Complete requests: 1000
Failed requests: 0
Write errors: 0
Non-2xx responses: 1000
Total transferred: 351000 bytes
HTML transferred: 0 bytes
Requests per second: 6.46 [#/sec] (mean)
Time per request: 773.440 [ms] (mean)
Time per request: 154.688 [ms] (mean, across all concurrent requests)
Transfer rate: 2.21 [Kbytes/sec] received

Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 0 0.1 0 3
Processing: 328 772 46.4 772 1040
Waiting: 327 771 46.4 772 1040
Total: 328 772 46.4 772 1040

Using mod_pagespeed and APC enabled.

Time taken for tests: 41.355400 seconds
Complete requests: 1000
Failed requests: 0
Write errors: 0
Non-2xx responses: 1000
Total transferred: 351000 bytes
HTML transferred: 0 bytes
Requests per second: 24.18 [#/sec] (mean)
Time per request: 206.777 [ms] (mean)
Time per request: 41.355 [ms] (mean, across all concurrent requests)
Transfer rate: 8.27 [Kbytes/sec] received

Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 6 134.1 0 3000
Processing: 88 199 28.4 202 459
Waiting: 88 199 28.4 201 459
Total: 88 205 137.2 202 3208

Using the WordPress W3 Total Cache plugin configured with Page, Database, Object, and Browser cache enabled the APC caching method and mod_pagespeed.

ime taken for tests: 37.750269 seconds
Complete requests: 1000
Failed requests: 0
Write errors: 0
Non-2xx responses: 1000
Total transferred: 351000 bytes
HTML transferred: 0 bytes
Requests per second: 26.49 [#/sec] (mean)
Time per request: 188.751 [ms] (mean)
Time per request: 37.750 [ms] (mean, across all concurrent requests)
Transfer rate: 9.06 [Kbytes/sec] received

Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 5 133.9 0 2996
Processing: 74 181 26.6 185 315
Waiting: 74 181 26.6 184 314
Total: 74 187 136.4 185 3178

As you can see, APC is the once caching method that makes a huge difference. Without APC, the server response time was just 6.46 requests per second and the load average peaked at about 12, while with the default APC configuration enabled, the server response time was 24.18 requests per second, with a load average peaking about 3. Adding the W3 Total Cache WordPress plugin helped performance slightly more, from 24.18 requests per second to 26.49 requests per second (load was about the same, including I/O activity). One interesting thing that I noticed is that with caching enabled, that is APC, the I/O usage spiked considerably. Most notably, MySQL was the high cpu usage process when doing the benchmarks. Since the caching is based in memory at this point it appears that the bottleneck in the web application is MySQL.


Awesome Applications: 

Apache: Installing mod_pagespeed on CentOS 6


rpm -ivh mod-pagespeed-stable_current_x86_64.rpm
warning: mod-pagespeed-stable_current_x86_64.rpm: Header V4 DSA/SHA1 Signature, key ID 7fac5991: NOKEY
error: Failed dependencies:
at is needed by mod-pagespeed-stable-


yum localinstall mod-pagespeed-stable_current_x86_64.rpm


Awesome Applications: 

Apache: RedirectMatch

For the longest time, I've been using mod_rewrite for any type of URL redirect that requires any sort of pattern matching.

A few days ago I migrated my Gallery web app from to and to my surprise, I learned that Redirect directive from mod_alias also has the RedirectMatch directive available, which essentially It's Redirect with regular expression support.

I was able to easily setup the simple redirect using RedirectMatch instead of using mod_rewrite.

RedirectMatch 301 ^/photos(/)?$
RedirectMatch 301 /photos/(.*)$1

Awesome Applications: 

PHP memory_limit stress testing

I wrote this code a couple of years ago that I found it was very useful when I was troubleshooting PHP memory limit settings. The script essentially creates one huge array until it runs out of memory.

ini_set('display_errors', true);
while (1) {
        echo 'Hello' . nl2br("\n");
        $array = array(1,2);
        while(1) {
                $tmp = $array;
                $array = array_merge($array, $tmp);
                echo memory_get_usage() . nl2br("\n");


Awesome Applications: 


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