Monthly Archives: May 2017

Enabling MySQL Slow Query Logs

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In the case your seeing very long pageload times, and have checked your application. It always pays to check the way in which the database performs when interacting with the application, especially if they are on either same or seperate server, as these significantly affect the way that your application will run.

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mysql> SET GLOBAL slow_query_log = 'ON' ;
Query OK, 0 rows affected (0.01 sec)
 
mysql> SET GLOBAL slow_query_log_file = '/slow_query_logs/slow_query_logs.txt';
Query OK, 0 rows affected (0.00 sec)
 
mysql> SET GLOBAL long_query_time = 5;
Query OK, 0 rows affected (0.00 sec)

Setting X-Frame-Options HTTP Header to allow SAME or NON SAME ORIGINS

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It’s possible to increase the security of a webserver running a website, by ensuring that the X-FRAME-OPTIONS header pushes a header to the browser, which enforces the origin (server) serving the site. It prevents the website then providing objects which are not local to the site, in the stream. An admirable option for those which wish to increase their server security.

Naturally, there are some reasons why you might want to disable this, and in proper context, it can be secure. Always be sure to discuss with your pentester or PCI compliance officer, such considerations before proceeding, especially making sure that if you do not want to use SAME ORIGIN you always use the most secure option for the required task. Always check if there is a better way to achieve what your trying to do, when making such changes to your server configuration.

Insecure X-Frame-Option allows remote non matching origins

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Header always append X-Frame-Options ALLOWALL

Secure X-Frame-Option imposes on the browser to not allow non origin(al) connections for the domain, which can prevent clickjack and other attacks.

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Header always append X-Frame-Options SAMEORIGIN

Moving a WordPress site – much ado about nothing !

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Have you noticed, there is all kinds of advise on the internet about the best way to move WordPress websites? There is literally a myriad of ways to achieve this. One of the methods I read on
wp.com was:

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Changing Your Domain Name and URLs
 
Moving a website and changing your domain name or URLs (i.e. from http://example.com/site to http://example.com, or http://example.com to http://example.net) requires the following steps - in sequence.
 
    Download your existing site files.
    Export your database - go in to MySQL and export the database.
    Move the backed up files and database into a new folder - somewhere safe - this is your site backup.
    Log in to the site you want to move and go to Settings > General, then change the URLs. (ie from http://example.com/ to http://example.net ) - save the settings and expect to see a 404 page.
    Download your site files again.
    Export the database again.
    Edit wp-config.php with the new server's MySQL database name, user and password.
    Upload the files.
    Import the database on the new server.

I mean this is truly horrifying steps to take, and I don’t see the point at all. This is how I achieved it for one my customers.

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1. Take customer Database Dump
2. Edit the database searching for 'siteurl' with vi
vi mysqldump.sql
:?siteurl
 
And just swap out the values, confirming after editing the file;
 
[root@box]# cat somemysqldump.sql  | grep siteurl -A 2
(1, 'siteurl', 'https://www.newsiteurl.com', 'yes'),
(2, 'home', 'https://www.newsiteurl.com', 'yes'),
(3, 'blogname', 'My website name', 'yes'),

Job done, no stress https://codex.wordpress.org/Moving_WordPress.

There might be additional bits but this is certainly enough for them to access the wp-admin panel. If you have problems add this line to the wp-config.php file;

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define('RELOCATE',true);

Just before the line which says

/* That’s all, stop editing! Happy blogging. */

And then just do the import/restore as normal;

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mysql -u newmysqluser -p newdatabase_to_import_to < old_database.sql

Simples! I really have no idea why it is made to be so complicated on other hosting sites or platforms.

Reverting a yum transaction & controlling auto-updates for yum-cron with excludes

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Hey, so a customer was running yum-cron, the Redhat version of Canoninical’s unattended upgrades. An auto update for a package ran, which actually broke their backend.

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# yum history info 172
Loaded plugins: replace, rhnplugin
This system is receiving updates from RHN Classic or Red Hat Satellite.
Transaction ID : 172
Begin time     : Sat May  6 05:45:29 2017
Begin rpmdb    : 742:11fcb243cc5701b9d2293d90cb4161e5edc34bb8
End time       :            05:45:31 2017 (2 seconds)
End rpmdb      : 742:0afbbf517315f18985b2d01d4c2e5250caf0afb5
User           : root <root>
Return-Code    : Success
Transaction performed with:
    Installed     rpm-4.11.3-21.el7.x86_64                @rhel-x86_64-server-7
    Installed     yum-3.4.3-150.el7.noarch                @rhel-x86_64-server-7
    Installed     yum-metadata-parser-1.1.4-10.el7.x86_64 @anaconda/7.1
    Installed     yum-rhn-plugin-2.0.1-6.1.el7_3.noarch   @rhel-x86_64-server-7
Packages Altered:
    Updated php56u-pecl-xdebug-2.5.1-1.ius.el7.x86_64 @rackspace-rhel-x86_64-server-7-ius
    Update                     2.5.3-1.ius.el7.x86_64 @rackspace-rhel-x86_64-server-7-ius
history info

The customer asked us to reverse the transaction, so I did, this was quite simple to do;

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[root@web user]# yum history undo 172
Loaded plugins: replace, rhnplugin
This system is receiving updates from RHN Classic or Red Hat Satellite.
Undoing transaction 172, from Sat May  6 05:45:29 2017
    Updated php56u-pecl-xdebug-2.5.1-1.ius.el7.x86_64 @rackspace-rhel-x86_64-server-7-ius
    Update                     2.5.3-1.ius.el7.x86_64 @rackspace-rhel-x86_64-server-7-ius
Resolving Dependencies
--> Running transaction check
---> Package php56u-pecl-xdebug.x86_64 0:2.5.1-1.ius.el7 will be a downgrade
---> Package php56u-pecl-xdebug.x86_64 0:2.5.3-1.ius.el7 will be erased
--> Finished Dependency Resolution
 
Dependencies Resolved
 
============================================================================================================================================================================================================================================
 Package                                                  Arch                                         Version                                               Repository                                                                Size
============================================================================================================================================================================================================================================
Downgrading:
 php56u-pecl-xdebug                                       x86_64                                       2.5.1-1.ius.el7                                       rackspace-rhel-x86_64-server-7-ius                                       205 k
 
Transaction Summary
============================================================================================================================================================================================================================================
Downgrade  1 Package
 
Total download size: 205 k
Is this ok [y/d/N]: y
Downloading packages:
Delta RPMs disabled because /usr/bin/applydeltarpm not installed.
php56u-pecl-xdebug-2.5.1-1.ius.el7.x86_64.rpm                                                                                                                                                                        | 205 kB  00:00:00
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
  Installing : php56u-pecl-xdebug-2.5.1-1.ius.el7.x86_64                                                                                                                                                                                1/2
  Cleanup    : php56u-pecl-xdebug-2.5.3-1.ius.el7.x86_64                                                                                                                                                                                2/2
  Verifying  : php56u-pecl-xdebug-2.5.1-1.ius.el7.x86_64                                                                                                                                                                                1/2
  Verifying  : php56u-pecl-xdebug-2.5.3-1.ius.el7.x86_64                                                                                                                                                                                2/2
 
Removed:
  php56u-pecl-xdebug.x86_64 0:2.5.3-1.ius.el7
 
Installed:
  php56u-pecl-xdebug.x86_64 0:2.5.1-1.ius.el7
 
Complete!

In CentOS 7 and I believe RedHat RHEL 7 as well, if you don’t want to disable yum-cron altogether by running a yum remove yum-cron, you could exclude the specific package, or use wildcards to exclude all of them like php* , http*, etc.

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vi /etc/yum/yum-cron.conf.

If you wish to exclude some packages from auto-update mechanism, you’ll have to add an exclude line, at the bottom of the file, in the base section.

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[base]
exclude = kernel* php* httpd*

etc, I hope that this is of some assist,

cheers &
Best wishes,
Adam