Posts Tagged ‘page’

How to easy add Joomla 1.5 donate Paypal capabilities with Joomla PAYPAL DONATION MODULE

Wednesday, June 15th, 2011

PayPal donation Module Joomla Screenshot

Many joomla CMS installations are for Non-profit organizations or Non Government organizations. These are organizations which are not officially making profit and therefore this instituations are interested into donations to support their activities.

In this occasions adding Joomla paypal capabilities is very essential. There are plenty of modules which enables Joomla to support paypal monetary payments, however many of them are either paid or requires registration and thus it’s quite time consuming to set up a decent PayPal supporting module for Joomla.
After a bit of investigation thanks God, I’ve come across a module that is free of charge, easily downloadable (wihtout registration) and is also relatively easy to configure, these module is called PAYPAL DONATION MODULE
I’ve mirored the module to my server, just in case if the module disappears in the future.

Here are a very brief explanation on how the module can be downloaded installed and configured:

First Download (mod_ojdonation_pp) Paypal Donation Module here

Install it as joomla module via:

Extensions -> Install/Uninstall
menu

Afterwards, go to:

Extensions -> Module Manager

In the list of modules you will notice the Donate module which will be disabled. Use the Enable button to enable it.

Next by clicking on the Donate Module Name, one can configure the module, where the most essential configuration values that needs to be filled in are:

1. Title: – The title of the donation form:
2. Donation Title: – Title of donation picture to show in the webpage
3. Donation Amount: – Default donation amount user will donate with paypal by clicking on Donate button
4. Currency – Default currency the donators will use to donate to configured paypal account
5. Paypal ID: – The email address of paypal account your donators will donate to (This was a bit hard to understand since Paypal ID is not a number ID but the email address configured as an username in PayPal).
6. Donation Description: – Description text to appear before the Donate button
7. Donation Footer: – Text to appear after the Donate button

There are two ways one could add the donation module to show the donation form, on the joomla website:
a. One is to enable the donation button on every joomla webpage (I don’t like this kind of behaviour).

To use this kind of donate button display approach, you will have to select from the Donation module, conf options:
– Show on FrontPage: and Show Title:

Also make sure the Enabled: option is set to Yes

b. Second approach is to set the PayPal Donation form only to appear on a single menu, to do so:

While in Paypal Donation Module configuration in Menu Assignment section, select:

Select Menu Item(s) from the List
instead of the default All value set for Menus.

The last setting to be choosen is the paypal donation form page location (where exactly on the selected pages the form will appear).

The form location is set from the Position: dropdown menu, the option which I found to be the best one for me was the bottom option. However just play with the Position setting and choose the one that will be best for you.

Then scroll on in the Menu Selection: and choose only the menus where you want a paypal donation form to appear.

Finally to save all the recent made settings, click on Apply and refreshing in a new page should show you paypal’s money donation form in joomla

If all is configured fine with Joomla’s – Paypal Donation Module you should get on your webpage:

PayPal donation Module in Joomla Screenshot
 

Remove URL from comments in WordPress Blogs and Websites to mitigate comment spam URLs in pages

Friday, February 20th, 2015

remove-comment-spam-url-field-wordpress-website-or-blog-working-how-to
If you're running a WordPress blog or Website where you have enabled comments for a page and your article or page is well indexing in Google (receives a lot of visit / reads ) daily, your site posts (comments) section is surely to quickly fill in with a lot of "Thank you" and non-sense Spam comments containing an ugly link to an external SPAM or Phishing website.

Such URL links with non-sense message is a favourite way for SPAMmers to raise their website incoming (other website) "InLinks" and through that increase current Search Engine position. 

We all know a lot of comments SPAM is generally handled well by Akismet but unfortunately still many of such spam comments fail to be identified as Spam  because spam Bots (text-generator algorithms) becomes more and more sophisticated with time, also you can never stop paid a real-persons Marketers to spam you with a smart crafted messages to increase their site's SEO ).
In all those cases Akismet WP (Anti-Spam) plugin – which btw is among the first "must have"  WP extensions to install on a new blog / website will be not enough ..

To fight with worsening SEO because of spam URLs and to keep your site's SEO better (having a lot of links pointing to reported spam sites will reduce your overall SEO Index Rate) many WordPress based bloggers, choose to not use default WordPress Comments capabilities – e.g. use exnternal commenting systems such as Disqus – (Web Community of Communities), IntenseDebate, LiveFyre, Vicomi

However as Disqus and other 3rd party commenting systems are proprietary software (you don't have access to comments data as comments are kept on proprietary platform and shown from there), I don't personally recommend (or use) those ones, yes Disqus, Google+, Facebook and other comment external sources can have a positive impact on your SEO but that's temporary event and on the long run I think it is more advantageous to have comments with yourself.
A small note for people using Disqos and Facebook as comment platforms – (just imagine if Disqos or Facebook bankrupts in future, where your comments will be? 🙂 )

So assuming that you're a novice blogger and I succeeded convincing you to stick to standard (embedded) WordPress Comment System once your site becomes famous you will start getting severe amount of comment spam. There is plenty of articles already written on how to remove URL comment form spam in WordPress but many of the guides online are old or obsolete so in this article I will do a short evaluation on few things I tried to remove comment spam and how I finally managed to disable URL link spam to appear on site.
 

1. Hide Comment Author Link (Hide-wp-comment-author-link)

This plugin is the best one I found and I started using it since yesterday, I warmly recommend this plugin because its very easy, Download, Unzip, Activate and there you're anything typed in URL field will no longer appear in Posts (note that the URL field will stay so if you want to keep track on person's input URL you can get still see it in Wp-Admin). I'm using default WordPress WRC (Kubrick), but I guess in most newer wordpress plugins is supposed to work. If you test it on another theme please drop a comment to inform whether works for you.  Hide Comment Author Link works on current latest Wordpress 4.1 websites.

A similar plugin to hide-wp-author-link that works and you can use is  Hide-n-Disable-comment-url-field, I tested this one but for some reason I couldn't make it work.

wordpress-remove-delete-hide-n-disable-url-comment-without-deleting-the-form-url-field-screenshot-reduce-comment-spam
Whatever I type in Website field in above form, this is wiped out of comment once submitted 🙂
 

2. Disable hide Comment URL (disable-hide-comment-url)

I've seen reports disable-hide-comment-url works on WordPress 3.9.1, but it didn't worked for me, also the plugin is old and seems no longer maintaned (its last update was 3.5 years ago), if it works for you please please drop in comment your WP version, on WP 4.1 it is not working.

disable-hide-comment-url-screenshot-plugin-to-disable-comment-url-spam-in-wordpress-sites
 


3. WordPress Anti-Spam plugin

WordPress Anti-Spam plugin is a very useful addition plugin to install next to Akismet. The plugin is great if you don't want to remove commenter URL to show in the post but want to cut a lot of the annoying Spam Robots crawling ur site.
 

Anti-spam plugin blocks spam in comments automatically, invisibly for users and for admins.

  • no captcha, because spam is not users' problem
  • no moderation queues, because spam is not administrators' problem
  • no options, because it is great to forget about spam completely

Plugin is easy to use: just install it and it just works.

Anti bot works fine on WP 4.1

4. Stop Spam Comments

Stop Spam Comments is:

  • Dead simple: no setup required, just activate it and enjoy your spam-free website.
  • Lightweight: no additional database queries, it doesn't add script files or other assets in your theme. This means your website performance will not be affected and your server will thank you.
  • Invisible by design: no captchas, no tricky questions or any other user interaction required at all.
     

Stop Spam Comments works fine on WP 4.1.

I've mentioned few of the plugins which can help you solve the problem, but as there are a lot of anti-spam URL plugins available for WP its up to you to test and see what fits you best. If you know or use some other method to protect yourself from Comment Url Spam to share it please.

Import thing to note is it usually a bad idea to mix up different anti-spam plugins so don't enable both Stop Spam Comments and WordPress Anti Spam plugin.

5. Comment Form Remove Url field Manually 

This (Liberian) South) African blog describes a way how to remove URL field URL manually

In short to Remove Url Comment Field manually either edit function.php (if you have Shell SSH access) or if not do it via Wp-Admin web interface:
 

WordPress admin page –> Appearance –> Editor


Paste at the end of file following PHP code:

 

add_filter('comment_form_default_fields', 'remove_url');
 function remove_url($fields)
 {
 if(isset($fields[‘url’]))
 unset($fields[‘url’]);
 return $fields;
 }


Now to make changes effect, Restart Apache / Nginx Webserver and clean any cache if you're using a plugin like W3 Total Cache plugin etc.

Other good posts describing some manual and embedded WordPress ways to reduce / stop comment spam is here and here, however as it comes to my blog, none of the described manual (code hack) ways I found worked on WordPress v. 4.1.
Thus I personally stuck to using Hide and Disable Comment URL plugin  to get rid of comment website URL.

Extracting pages and page ranges, protect with password and remove password from PDF on GNU / Linux with QPDF – Linux Manipulating PDF files from command line

Friday, August 8th, 2014

qpdf-logo-extract-pages-page-ranges-protect-pdf-with-password-remove-password-from-pdf-linux-qpdf-manipulating-pdf-files-on-gnu-linux-and-bsd
If're a Linux user and you need to script certain page extraction from PDF files, crypt protect with password a PDF file or decrypt (remote password protection from PDF) or do some kind of structural transformation of existing PDF file you can use a QPDF command line utility. qpdf is in active development and very convenient tool for Website developers (PHP / Perl / Python), as often on websites its necessery to write code to cut / tailer / restructure PDFs.

1. Install QPDF from deb / rpm package

qpdf is instalalble by default in deb repositories on Debian / Ubuntu GNU / (deb derivative) Linux-es to install it apt-get it

apt-get install –yes qpdf

On RPM based distribution CentOS / SuSE / RHEL / Fedora Linux to install qpdf, fetch the respective distribution binary from rpmfind.net or to install latest version of qpdf build it from source code.

2. Install QPDF from source

To build latest qpdf from source

  • on RPM based distributions install with yum fullowing packages:

yum -y install zlib-devel pcre-devel gcc gcc-c++

  • on Deb based Linuces, you will need to install

apt-get install –yes build-essential gcc dpkg-dev g++ zlib1g-dev


Then to build gather latest qpdf source from here

 

cd /usr/local/src
wget -q https://www.pc-freak.net/files/qpdf-5.1.2.tar.gz
tar -zxvf qpdf-5.1.2.tar.gz
cd qpdf-5.1.2/
./configure
make
make install


Once it is installed, if you get error on qpdf runtime:
 

/usr/local/bin/qpdf: error while loading shared libraries: libqpdf.so.13: cannot open shared object file: No such file or directory

To solve the error find in your compile directory libqpdf.so.13 and copy it to /usr/lib or /usr/local/lib

 cp -rpf ./libqpdf/build/.libs/libqpdf.so.13 /usr/local/lib


3. Decrypt password encrypted (protected) PDF file

if you have time and you like reading be sure to check the extensive qpdf-manual.

To remove password from a PDF file protected with a password with qpdf

qpdf –password=SECRET-PASSWORD –decrypt input-file.pdf output-file.pdf

QPDF has a vast range of split and merge features. It can combine all the files in a folder (*.pdf), you can use it to try to recover damaged pdf files, extract individual pages from PDF, dump and reverse page range, make new created PDF with old PDF's reversed pages (pages 1,2,3,4 to become in order 4,3,2,1), apply some single pdf file metadata to multiple files.

4. Try to Recover damaged PDF file


To try to recover some damaged file with qpdf:
 

qpdf file-to-repair.pdf repaired-file.pdf

5. Extract certain pages or page range from PDF

It is recommended to use the version built from source to extract certain page range from PDF
 

/usr/local/bin/qpdf –empty –pages input-file.pdf 1-5 — outfile-file.pdf


If you wanted to take pages 1–5 from file1.pdf and pages 11–15 from file2.pdf in reverse, you would run
 

qpdf file1.pdf –pages file1.pdf 1-5 file2.pdf 15-11 — outfile.pdf

 

How to remove parameters from URL on Apache (Reverse Proxy) with .htaccess and mod_rewrite – Remove query string from Link

Thursday, December 11th, 2014

Desktop/How_to_remove_parameters_from_URL_on_Apache_with_htaccess_and_SAP
Recently I had a task to delete number of set variables (listed parameters) from URL address on a Apache webserver serving as Reverse Proxy. 
To make it more clear exact task was when customers call the URL https://companywebsite-url.com (all subdomains included) the following URL parameters should always be deleted by the reverse proxy

– ebppMode 
– ebppObjectKey 
– ebppObjectType 
– ebppSystem 
– logSys 

The paramets are part of SAP Biller Direct in a Portal (based on the famous SAP database) which is often deployed as a component of Internet Sales (ISA) / Supplier Relationship Management (SRM) / CRM
, if a user is logged in with his Credentials (KID (Key ID) / Admin KID)  into the system. The EBPP part of most variables stands for (Electronic Bill Presentment and Payment).

 By passing above parameters to Website, modes of use, user accounts switched with which user is logged into the system system logs read and other stuff which can turn to be a severe security hole.
As most of Big Companies, does pass there web traffic via a "transparent" Reverse Proxy,it is a good security practice for SAP Biller Direct (including CRM systems( to wipe out this variables

Here is the mod_rewrite working rules that I used to achieve the delete variable from URL address task:
 

   RewriteEngine On
   RewriteCond %{QUERY_STRING} ^(.*)bebppMode=(w*)b(.*)
   RewriteRule (.*) $1?%1%3

   RewriteCond %{QUERY_STRING} ^(.*)bebppObjectKey=(w*)b(.*)
   RewriteRule (.*) $1?%1%3

   RewriteCond %{QUERY_STRING} ^(.*)bebppObjectType=(w*)b(.*)
   RewriteRule (.*) $1?%1%3

   RewriteCond %{QUERY_STRING} ^(.*)bebppSystem=(w*)b(.*)
   RewriteRule (.*) $1?%1%3

   RewriteCond %{QUERY_STRING} ^(.*)logSys=(w*)b(.*)
   RewriteRule (.*) $1?%1%3

   RewriteCond %{QUERY_STRING} ^(.*)&&(.*)
   RewriteRule (.*) $1?%1%3


P.S. I've implemented above Rewrite rules into all Virtualhosts of Applications (in that case all living in the same httpd.conf on SuSE (SLES) 11 SP1 Enterprise Linux server).
To make changes affective, restarted HTTPD Webserver:
 

/etc/init.d/httpd restart


The sesult is:

https://companywebsite-url.com/start.html?page=start&ebppMode=A&ebppSystem=Test

leads to a internal URL redirection

https://companywebsite-url.com/start.html?page=start

without parameters ebppSystem, ebppMode, ebppObjectKey, ebppSystem,   logSys .

Other mod_rewrite rule that works but is too ugly and when I tried it on Debian Linux host was behaving strange (including in the rewrited URL address the directory address of the PHP twice):

RewriteCond %{QUERY_STRING} (.*)(^|&|%26|%20)ebppMode(=|%3D)([^&]+)(.*)$ [OR]
RewriteCond %{QUERY_STRING} (.*)(^|&|%26|%20)ebppObjectKey(=|%3D)([^&]+)(.*)$ [OR]
RewriteCond %{QUERY_STRING} (.*)(^|&|%26|%20)ebppObjectType(=|%3D)([^&]+)(.*)$ [OR]
RewriteCond %{QUERY_STRING} (.*)(^|&|%26|%20)ebppSystem(=|%3D)([^&]+)(.*)$ [OR]
RewriteCond %{QUERY_STRING} (.*)(^|&|%26|%20)logSys(=|%3D)([^&]+)(.*)$

RewriteRule (.*) /$1?%1%5 [R=307]

 Well anyways, with the first bunch of mod_rewrite rule it works fine.

Thanks God Problem Solved 🙂

Secure Apache webserver against basic Denial of Service attacks with mod_evasive on Debian Linux

Wednesday, September 7th, 2011

Secure Apache against basic Denial of Service attacks with mod evasive, how webserver DDoS works

One good module that helps in mitigating, very basic Denial of Service attacks against Apache 1.3.x 2.0.x and 2.2.x webserver is mod_evasive

I’ve noticed however many Apache administrators out there does forget to install it on new Apache installations or even some of them haven’t heard about of it.
Therefore I wrote this small article to create some more awareness of the existence of the anti DoS module and hopefully thorugh it help some of my readers to strengthen their server security.

Here is a description on what exactly mod-evasive module does:

debian:~# apt-cache show libapache2-mod-evasive | grep -i description -A 7

Description: evasive module to minimize HTTP DoS or brute force attacks
mod_evasive is an evasive maneuvers module for Apache to provide some
protection in the event of an HTTP DoS or DDoS attack or brute force attack.
.
It is also designed to be a detection tool, and can be easily configured to
talk to ipchains, firewalls, routers, and etcetera.
.
This module only works on Apache 2.x servers

How does mod-evasive anti DoS module works?

Detection is performed by creating an internal dynamic hash table of IP Addresses and URIs, and denying any single IP address which matches the criterias:

  • Requesting the same page more than number of times per second
  • Making more than N (number) of concurrent requests on the same child per second
  • Making requests to Apache during the IP is temporarily blacklisted (in a blocking list – IP blacklist is removed after a time period))

These anti DDoS and DoS attack protection decreases the possibility that Apache gets DoSed by ana amateur DoS attack, however it still opens doors for attacks who has a large bot-nets of zoombie hosts (let’s say 10000) which will simultaneously request a page from the Apache server. The result in a scenario with a infected botnet running a DoS tool in most of the cases will be a quick exhaustion of system resources available (bandwidth, server memory and processor consumption).
Thus mod-evasive just grants a DoS and DDoS security only on a basic, level where someone tries to DoS a webserver with only possessing access to few hosts.
mod-evasive however in many cases mesaure to protect against DoS and does a great job if combined with Apache mod-security module discussed in one of my previous blog posts – Tightening PHP Security on Debian with Apache 2.2 with ModSecurity2
1. Install mod-evasive

Installing mod-evasive on Debian Lenny, Squeeze and even Wheezy is done in identical way straight using apt-get:

deiban:~# apt-get install libapache2-mod-evasive
...

2. Enable mod-evasive in Apache

debian:~# ln -sf /etc/apache2/mods-available/mod-evasive.load /etc/apache2/mods-enabled/mod-evasive.load

3. Configure the way mod-evasive deals with potential DoS attacks

Open /etc/apache2/apache2.conf, go down to the end of the file and paste inside, below three mod-evasive configuration directives:

<IfModule mod_evasive20.c>
DOSHashTableSize 3097DOS
PageCount 30
DOSSiteCount 40
DOSPageInterval 2
DOSSiteInterval 1
DOSBlockingPeriod 120
#DOSEmailNotify hipo@mymailserver.com
</IfModule>

In case of the above configuration criterias are matched, mod-evasive instructs Apache to return a 403 (Forbidden by default) error page which will conserve bandwidth and system resources in case of DoS attack attempt, especially if the DoS attack targets multiple requests to let’s say a large downloadable file or a PHP,Perl,Python script which does a lot of computation and thus consumes large portion of server CPU time.

The meaning of the above three mod-evasive config vars are as follows:

DOSHashTableSize 3097 – Increasing the DoSHashTableSize will increase performance of mod-evasive but will consume more server memory, on a busy webserver this value however should be increased
DOSPageCount 30 – Add IP in evasive temporary blacklist if a request for any IP that hits the same page 30 consequential times.
DOSSiteCount 40 – Add IP to be be blacklisted if 40 requests are made to a one and the same URL location in 1 second time
DOSBlockingPeriod 120 – Instructs the time in seconds for which an IP will get blacklisted (e.g. will get returned the 403 foribden page), this settings instructs mod-evasive to block every intruder which matches DOSPageCount 30 or DOSSiteCount 40 for 2 minutes time.
DOSPageInterval 2 – Interval of 2 seconds for which DOSPageCount can be reached.
DOSSiteInterval 1 – Interval of 1 second in which if DOSSiteCount of 40 is matched the matched IP will be blacklisted for configured period of time.

mod-evasive also supports IP whitelisting with its option DOSWhitelist , handy in cases if for example, you should allow access to a single webpage from office env consisting of hundred computers behind a NAT.
Another handy configuration option is the module capability to notify, if a DoS is originating from a number of IP addresses using the option DOSEmailNotify
Using the DOSSystemCommand in relation with iptables, could be configured to filter out any IP addresses which are found to be matching the configured mod-evasive rules.
The module also supports custom logging, if you want to keep track on IPs which are found to be trying a DoS attack against the server place in above shown configuration DOSLogDir “/var/log/apache2/evasive” and create the /var/log/apache2/evasive directory, with:
debian:~# mkdir /var/log/apache2/evasive

I decided not to log mod-evasive DoS IP matches as this will just add some extra load on the server, however in debugging some mistakenly blacklisted IPs logging is sure a must.

4. Restart Apache to load up mod-evasive debian:~# /etc/init.d/apache2 restart
...

Finally a very good reading which sheds more light on how exactly mod-evasive works and some extra module configuration options are located in the documentation bundled with the deb package to read it, issue:

debian:~# zless /usr/share/doc/libapache2-mod-evasive/README.gz

Change Internet Explorer to open in tabs / Force IE Open Links in new tab

Thursday, November 28th, 2013

Internet-explorer multiple opened windows annoying behaviour fix howto picture

If you have to work on MS Windows 7 / 8 with Internet Explorer for the reason websites you're forced to work are only properly working under IE. This is common in big companies like my employer Hewlett Packard or IBM for instance. You certainly have been annoyed by default Internet Explorer 7 / Internet Explorer 8 or EI 9 behaviour to open each new link in separate Windows. By default normal browsers like Opera, Firefox and Google Chrome does not behave in such irritating ways but open each new link in separate tab. If you're like me used to work most of your life with Firefox, this IE behavior can quickly drive you "crazy" so you will look for fastly to change that abnormal browser actions. What makes things with default IE behavior even more messy is the fact that there are sites which automatically open in Separate tab (for they were javascripted) to do so and ones that open in new Window making the whole browsing experience a "pure windows hell".

Thanks God IE new window page popups can be easily changed

1. Open Internet Explorer and Click on
Tools
-> Internet Options

Internet explorer Internet options menu screenshot
(Note: if your version of Internet Explorer is hiding menus press Alt key to make it visualize menus)

2.
In General (tab) select on (Change how webpage is displayed in Tabs) Settings

Internet Explorer internet options change webpage displayed in tabs settings screenshot

3.  Under field When a popup is encountered: Choose radio button of ( Always Open Pop-ups in new tab )

Internet explorer tabbed browser settings Microsoft Windows 8 screenshot

After Apply and OK press finally Pages will start opening in a "human readable" way 🙂 in new Tabs. Hope this hint helps someone. Enjoy 🙂

Tracking I/O hard disk server bottlenecks with iostat on GNU / Linux and FreeBSD

Tuesday, March 27th, 2012

Hard disk overhead tracking on Linux and FreeBSD with iostat

I've earlier wrote an article How to find which processes are causing hard disk i/o overhead on Linux there I explained very rawly few tools which can be used to benchmark hard disk read / write operations. My prior article accent was on iotop and dstat and it just mentioned of iostat. Therefore I've wrote this short article in attempt to explain a bit more thoroughfully on how iostat can be used to track problems with excessive server I/O read/writes.

Here is the command man page description;
iostatReport Central Processing Unit (CPU) statistics and input/output statistics for devices, partitions and network filesystems

I will further proceed with few words on how iostat can be installed on various Linux distros, then point at few most common scenarious of use and a short explanation on the meaning of each of the command outputs.

1. Installing iostat on Linux

iostat is a swiss army knife of finding a server hard disk bottlenecks. Though it is a must have tool in the admin outfut, most of Linux distributions will not have iostat installed by default.
To have it on your server, you will need to install sysstat package:

a) On Debian / Ubuntu and other Debian GNU / Linux derivatives to install sysstat:

debian:~# apt-get --yes install sysstat

b) On Fedora, CentOS, RHEL etc. install is with yum:

[root@centos ~]# yum -y install sysstat

c) On Slackware Linux sysstat package which contains iostat is installed by default. 

d) In FreeBSD, there is no need for installation of any external package as iostat is part of the BSD world (bundle commands).
I should mention bsd iostat and Linux's iostat commands are not the same and hence there use to track down hard disk bottlenecks differs a bit, however the general logic of use is very similar as with most tools in BSD and Linux.

2. Checking a server hard disk for i/o disk bottlenecks on G* / Linux

Once having the sysstat installed on G* / Linux systems, the iostat command will be added in /usr/bin/iostat
a) To check what is the hard disk read writes per second (in megabytes) use:

debian:~# /usr/bin/iostat -m
Linux 2.6.32-5-amd64 (debian) 03/27/2012 _x86_64_ (8 CPU)
avg-cpu: %user %nice %system %iowait %steal %idle
15.34 0.36 2.76 2.66 0.00 78.88
Device: tps MB_read/s MB_wrtn/s MB_read MB_wrtn
sda 63.89 0.48 8.20 6730223 115541235
sdb 64.12 0.44 8.23 6244683 116039483
md0 2118.70 0.22 8.19 3041643 115528074

In the above output the server, where I issue the command is using sda and sdb configured in software RAID 1 array visible in the output as (md0)

The output of iostat should already be easily to read, for anyone who didn't used the tool here is a few lines explanation of the columns:

The %user 15.34 meaning is that 15.34 out of 100% possible i/o load is generad by system level read/write operations.
%nice – >Show the percentage of CPU utilization that occurred while executing at the user level with nice priority.
%iowait – just like the top command idle it shows the idle time when the system didn't have an outstanding disk I/O requests.
%steal – show percentage in time spent in time wait of CPU or virtual CPUs to service another virtual processor (high numbers of disk is sure sign for i/o problem).
%idle – almost the same as meaning to %iowait
tps – HDD transactions per second
MB_read/s (column) – shows the actual Disk reads in Mbytes at the time of issuing iostat
MB_wrtn/s – displays the writes p/s at the time of iostat invocation
MB_read – shows the hard disk read operations in megabytes, since the server boot 'till moment of invocation of iostat
MB_wrtn – gives the number of Megabytes written on HDD since the last server boot filesystem mount

The reason why the Read / Write values for sda and sdb are similar in this example output is because my disks are configured in software RAID1 (mirror)

The above iostat output reveals in my specific case the server is experiencing mostly Disk writes (observable in the high MB_wrtn/s 8.19 md0 in the above sample output).

It also reveals, the I/O reads experienced on that server hard disk are mostly generated as a system (user level load) – see (%user 15.34 and md0 2118.70).

For all those not familiar with system also called user / level load, this is all kind of load which is generated by running programs on the server – (any kind of load not generated by the Linux kernel or loaded kernel modules).

b) To periodically keep an eye on HDD i/o operations with iostat, there are two ways:

– Use watch in conjunction with iostat;

[root@centos ~]# watch "/usr/bin/iostat -m"
Every 2.0s: iostat -m Tue Mar 27 11:00:30 2012
Linux 2.6.32-5-amd64 (centos) 03/27/2012 _x86_64_ (8 CPU)
avg-cpu: %user %nice %system %iowait %steal %idle
15.34 0.36 2.76 2.66 0.00 78.88
Device: tps MB_read/s MB_wrtn/s MB_read MB_wrtn
sda 63.89 0.48 8.20 6730255 115574152
sdb 64.12 0.44 8.23 6244718 116072400
md0 2118.94 0.22 8.20 3041710 115560990
Device: tps MB_read/s MB_wrtn/s MB_read MB_wrtn
sda 55.00 0.01 25.75 0 51
sdb 52.50 0.00 24.75 0 49
md0 34661.00 0.01 135.38 0 270

Even though watch use and -d might appear like identical, they're not watch does refresh the screen, executing instruction similar to the clear command which clears screen on every 2 seconds, so the output looks like the top command refresh, while passing the -d 2 will output the iostat command output on every 2 secs in a row so all the data is visualized on the screen. Hence -d 2 in cases, where more thorough debug is necessery is better. However for a quick routine view watch + iostat is great too.

c) Outputting extra information for HDD input/output operations;

root@debian:~# iostat -x
Linux 2.6.32-5-amd64 (debian) 03/27/2012 _x86_64_ (8 CPU)
avg-cpu: %user %nice %system %iowait %steal %idle
15.34 0.36 2.76 2.66 0.00 78.88
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util
sda 4.22 2047.33 12.01 51.88 977.44 16785.96 278.03 0.28 4.35 3.87 24.72
sdb 3.80 2047.61 11.97 52.15 906.93 16858.32 277.05 0.03 5.25 3.87 24.84
md0 0.00 0.00 20.72 2098.28 441.75 16784.05 8.13 0.00 0.00 0.00 0.00

This command will output extended useful Hard Disk info like;
r/s – number of read requests issued per second
w/s – number of write requests issued per second
rsec/s – numbers of sector reads per second
b>wsec/s – number of sectors wrote per second
etc. etc.

Most of ppl will never need to use this, but it is good to know it exists.

3. Tracking read / write (i/o) hard disk bottlenecks on FreeBSD

BSD's iostat is a bit different in terms of output and arguments.

a) Here is most basic use:

freebsd# /usr/sbin/iostat
tty ad0 cpu
tin tout KB/t tps MB/s us ni sy in id
1 561 45.18 44 1.95 14 0 5 0 82

b) Periodic watch of hdd i/o operations;

freebsd# iostat -c 10
tty ad0 cpu
tin tout KB/t tps MB/s us ni sy in id
1 562 45.19 44 1.95 14 0 5 0 82
0 307 51.96 113 5.73 44 0 24 0 32
0 234 58.12 98 5.56 16 0 7 0 77
0 43 0.00 0 0.00 1 0 0 0 99
0 485 0.00 0 0.00 2 0 0 0 98
0 43 0.00 0 0.00 0 0 1 0 99
0 43 0.00 0 0.00 0 0 0 0 100
...

As you see in the output, there is information like in the columns tty, tin, tout which is a bit hard to comprehend.
Thanksfully the tool has an option to print out only more essential i/o information:

freebsd# iostat -d -c 10
ad0
KB/t tps MB/s
45.19 44 1.95
58.12 97 5.52
54.81 108 5.78
0.00 0 0.00
0.00 0 0.00
0.00 0 0.00
20.48 25 0.50

The output info is quite self-explanatory.

Displaying a number of iostat values for hard disk reads can be also achieved by omitting -c option with:

freebsd# iostat -d 1 10
...

Tracking a specific hard disk partiotion with iostat is done with:

freebsd# iostat -n /dev/ad0s1a
tty cpu
tin tout us ni sy in id
1 577 14 0 5 0 81
c) Getting Hard disk read/write information with gstat

gstat is a FreeBSD tool to print statistics for GEOM disks. Its default behaviour is to refresh the screen in a similar fashion like top command, so its great for people who would like to periodically check all attached system hard disk and storage devices:

freebsd# gstat
dT: 1.002s w: 1.000s
L(q) ops/s r/s kBps ms/r w/s kBps ms/w %busy Name
0 10 0 0 0.0 10 260 2.6 15.6| ad0
0 10 0 0 0.0 10 260 2.6 11.4| ad0s1
0 10 0 0 0.0 10 260 2.8 12.5| ad0s1a
0 0 0 0 0.0 0 0 0.0 20.0| ad0s1b
0 0 0 0 0.0 0 0 0.0 0.0| ad0s1c
0 0 0 0 0.0 0 0 0.0 0.0| ad0s1d
0 0 0 0 0.0 0 0 0.0 0.0| ad0s1e
0 0 0 0 0.0 0 0 0.0 0.0| acd0

It even has colors if your tty supports colors 🙂

Another useful tool in debugging the culprit of excessive hdd I/O operations is procstat command:

Here is a sample procstat run to track (httpd) one of my processes imposing i/o hdd load:

freebsd# procstat -f 50404
PID COMM FD T V FLAGS REF OFFSET PRO NAME
50404 httpd cwd v d -------- - - - /
50404 httpd root v d -------- - - - /
50404 httpd 0 v c r------- 56 0 - -
50404 httpd 1 v c -w------ 56 0 - -
50404 httpd 2 v r -wa----- 56 75581 - /var/log/httpd-error.log
50404 httpd 3 s - rw------ 105 0 TCP ::.80 ::.0
50404 httpd 4 p - rw---n-- 56 0 - -
50404 httpd 5 p - rw------ 56 0 - -
50404 httpd 6 v r -wa----- 56 25161132 - /var/log/httpd-access.log
50404 httpd 7 v r rw------ 56 0 - /tmp/apr8QUOUW
50404 httpd 8 v r -w------ 56 0 - /var/run/accept.lock.49588
50404 httpd 9 v r -w------ 1 0 - /var/run/accept.lock.49588
50404 httpd 10 v r -w------ 1 0 - /tmp/apr8QUOUW
50404 httpd 11 ? - -------- 2 0 - -

Btw fstat is sometimes helpful in identifying the number of open files and trying to estimate which ones are putting the hdd load.
Hope this info helps someone. If you know better ways to track hdd excessive loads on Linux / BSD pls share 'em pls.
 

How to convert file content encoded in windows-cp1251 charset to UTF-8 (with iconv) to be delivered properly encoded to browsing end clients

Wednesday, May 16th, 2012

windows-cp1251 bulgarian to UTF-8 / Encoding Communication Decoding Communication Funny Picture

I have a bunch of old html files all encoded in the historically obsolete Windows-cp1251. Windows-CP1251 used to be common used 7 years ago and therefore still big portions of the web content in Bulgarian / Russian Cyrillic is still transferred to the end users in this encoding.

This was just before the "UTF-8 revolution", where massively people started using UTF-8,
Well it was clear the specific national country text encoding standards will quickly be moved by to UTF-8 – Universal Encoding format which abbreviation stands for (Unicode Transformation Format).

Though UTF-8 was clear to be "the future", many web developers mostly because of their incompetency or using an old sources of learning how to writen in HTML continued to use windows-cp1251 in HTMLs. I'm even convinced, there are still developers out there who are writting websites for Bulgarian / Russian / Macedonian customers using obsolete encodings …

The smarter developers of those accustomed to windows-cp1251, KOI-8R etc. etc., were using the meta tag to specify the type of charset of the web page content with:

<meta http-equiv="content-type" content="text/html;charset=windows-cp1251">

or

<meta http-equiv="content-type" content="text/html;charset=koi-8r">

Anyhow, still many devs even didn't placed the windows-cp1251 in the head of the HTML …

The result for the system administrator is always a mess – a lot of webpages that are showing like unreadable signs and tons of unhappy customers.
As always the system administrator is considered responsible, for the programmer mistakes :). So instead of programmers fix their bad cooking, the admin has to fix it all!

One quick work around me as admin has applied to failing to display pages in Cyrillic using the Windows-cp1251 character encoding was to force windows-cp1251 as a default encoding for the whole virtualhost or Apache directory with Apache directives like:

<VirtualHost *:80>
ServerAdmin some_user@some_host.com
DocumentRoot /var/www/html
AddDefaultCharset windows-cp1251
ServerName the_host_name.com
ServerAlias www.the_host_name.com
....
....
<Directory>
AddDefaultCharset windows-cp1251
>/Directory>
</VirtualHost>

Though this mostly would, work there are some occasions, where only a particular html files from all the content served by Apache is encoded in windows-cp1251, if most of the content is already written in UTF-8, this could be a big issues as you cannot just change the UTF-8 globally to windows-cp1251, just because few pages are written in archaic encoding….
Since most of the content is displayed to the client by Apache (as prior explained) just fine, only particular htmls lets's ay single.html, single2.html etc. etc. are displayed with some question marks or some non-human readable "hieroglyphs".

Below is a screenshot from two pages returned to my browser in wrongly set htmls charset:

Improper Windows CP1251 encoding with Apache set to serve UTF-8 encoding questiomarks

Improper Windows CP1251 delivered page in UTF-8 browser view

Apache returns cp1251 in some non-UTF8 wrong encoding (webserver improperly served cyrillic encoding)

Improperly served encoding CP1251 delivered by Apache in non-utf-8 encoding

When this kind of issues occur, the only solution is to simply login to the server and use iconv command to convert all files returning unreadable content from whatever the non UTF-8 encoding is lets say in my case Bulgarian typeset of cp1251 to UTF-8

Here is how the iconv command to convert between windows-cp1251 to utf-8 the two sample files named single1.html and single2.html

server:/web# /usr/bin/iconv -f WINDOWS-1251 -t UTF-8 single1.html > single1.html.utf8
server:/web# mv single1.html single1.html.bak;
server:/web# mv single1.html.utf8 single1.html
server:/web# /usr/bin/iconv -f WINDOWS-1251 -t UTF-8 single2.html > single2.html.utf8
server:/web# mv single2.html single2.html.bak;
server:/web# mv single2.html.utf8 single2.html

I always, make copies of the original cp1251 encoded files (as you see mv single1.html single1.html.bak), because if something goes wrong with convertion I can easily revert back.

If there are 10 files with consequential numbers naming they can be converted using a short for loop, like so:

server:/web# for i $(seq 1 10); do
/usr/bin/iconv -f WINDOWS-1251 -t UTF-8 single$i.html > single$i.html.utf8;mv single$i.html single$i.html.bak
mv single$i.html.utf8 single$i.html
done

Just as earlier mentioned if single1.html, single2.html … has in the html <head>:

<meta http-equiv="Content-Type" content="text/html; charset=windows-1251">

You should open, each of the files in question and wipe out the line either by hand or use sed to wipe it in one loop if it has to be done for lets say 10 files named (single{1..10})

server:/web# for i in $(seq 1 10); do
sed '/<meta http-equiv="Content-Type" content="text\/html; charset=windows-1251>/d' single$i.txt > single$i.txt.new;
mv single$i.txt single$i.txt.bak;
mv single$i.txt.new single$i.txt

Well now,

A list of Christian Metal website resources on the Net for Christian Metal lovers

Thursday, July 26th, 2012

I’ve been an old times Metal head. The moment I accepted Jesus Christ as a Lord and Saviour and been visited by the Lord’s Holy Ghost grace, my life changed severely. I found out most of the metal bands, I used to be regularly listening to is against Christ and anti-christian in essence, I still however hold my love for Metal as my teenage years were dominated by Metal Music. Happily I found there is plenty of nice Metal music a Metal head could enjoy that are written for glorification of Christ and hence did not have the negative spiritual anti-christian charge that is so typical for a lot of the bads in the metal music world. Recently I’m not listening to as much music as few years from now but still every now and then I like playing some of my old Christian metal loved bands. I was maintaining a small list of Christian metal nice bands I found and playlisted on youtube. If you’re a metal geek you might enjoy my old christian metal playlist here 🙂.

For Christians, who are looking for online Christian Metal community I also suggest you check out Firestream – The believer’s Heavy Music Refugee . There are plenty of other interesting places on the net dedicated for Christian metal fans;;;

I will end up this post with 2 videos of one very favourite Ukrainian Christian Metal band – Angel 7;

Angel 7 – Jesus the Saviour

Angel 7 – The Last Day

There are probably plenty of other nice Christian Metal sites and resources on the net; surely I’m missing a lot here? if you know some other good Christian Rock / Metal resources please drop a comment.

How to fix bug with WordPress domain extra trailing slash (Double wordpress trailing slash)

Monday, July 9th, 2012

How to fix bug with wordpress extra slash, domain double slash issue pic

2 of the wordpress installations, I take care for had been reported an annoying bug today by some colleagues.
The bug consisted in double trailing slash at the end of the domain url e.g.;

http://our-company-domainname.com//

As a result in the urls everywhere there was the double trailing slash appearing i.e.::

http://our-company-domainname.com//countact-us/
http://our-company-domainname.com//languages/

etc.

The bug was reported to happen in the multiolingual version of the wordpress based sites, as the Qtranslate plugin is used on this installations to achieve multiple languages it seemed at first logical that the double slash domain and url wordpress issues are caused for some reason by qTranslate.

Therefore, I initially looked for the cause of the problem, within the wordpress admin settings for qTranslate plugin. After not finding any clue pointing the bug to be related to qTranslate, I've then checked the settings for each individual wordpress Page and Post (There in posts usually one can manually set the exact url pointing to each post and page).
The double slash appeared also in each Post and Page and it wasn't possible to edit the complete URL address to remove the double trailin slashes. My next assumption was the cause for the double slash appearing on each site link is because of something wrong with the sites .htaccess, therefore I checked in the wp main sites directory .htaccess
Strangely .htacces seemed OKAY and there was any rule that somehow might lead to double slashes in URL. WP-sites .htaccess looked like so:
 

server:/home/wp-site1/www# cat .htaccess
RewriteEngine On
RewriteBase /

# Rewrite rules for new content and scripts folder
RewriteRule ^jscripts/(.*)$ wp-includes/js/$1
RewriteRule ^gallery/(.*)$ wp-content/uploads/$1
RewriteRule ^modules/(.*)$ wp-content/plugins/$1
RewriteRule ^gui/(.*)/(.*)$ wp-content/themes/$1/$2 [L]

# Disable direct acceees to wp files if referer is not valid
#RewriteCond %{THE_REQUEST} .wp-*
#RewriteCond %{REQUEST_URI} .wp-*
#RewriteCond %{REQUEST_URI} !.*media-upload.php.*
#RewriteCond %{HTTP_REFERER} !.*cadia.*
#RewriteRule . /error404 [L]

# Standard WordPress rewrite
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]

Onwards, I thought a possible way to fix bug by adding mod_rewrite rules in .htaccess which would do a redirect all requests to http://www.our-company-domainname.com//contact-us/ to http://www.our-company-domainname.com//contact-us/ etc. like so:

RewriteRule ^/(.*)$ /$1

This for unknown reasons to me didn't worked either, finally thanks God I remembered to check the variables in wp-config.php (some month ago or so I added there some variables in order to improve the wordpress websites opening times).

I've figured out I did a mistake in one of the variables by adding an ending slash to the URL. The variable added was:

define('WP_HOME','http://our-company-domainname.com/');

whether instead it should be without the ending trailing slash like so:

define('WP_HOME','http://our-company-domainname.com');

By removing the ending trailing slash:

define('WP_HOME','http://our-company-domainname.com/');

to:

define('WP_HOME','http://our-company-domainname.com');
fixed the issue.
Cheers 😉