Posts Tagged ‘impact’

Script to Automatically change current MySQL server in wp-config.php to another MySQL host to minimize WordPress and Joomla downtimes

Friday, July 20th, 2012

I'm running a two servers for a couple of home hosted websites. One of the servers is serving as Apache host1 and has configured MySQL running on it and the second is used just for database host2 – (has another MySQL configured on it).
The MySQL servers are not configured to run as a MySQL MASTER and MySQL SLAVE (no mysql replication), however periodically (daily), I have a tiny shell script that is actualizing the data from the active SQL host2 server to host1.

Sometimes due to electricity problems or CPU overheats the active MySQL host at host2 gets stoned and stops working causing the 2 WordPress based websites and One joomla site inaccessible.
Until I manually get to the machine and restart host2 the 3 sites are down from the net and as you can imagine this has a very negative impact on the existing website indexing (PageRank) in Google.

When I'm at home, this is not a problem as I have physical access to the servers and if somethings gets messy I fix it quickly. The problem comes, whether I'm travelling or in another city far from home and there is no-one at home to give the hanged host hard reboot ….

Lately the problems with hang-ups of host2 happaned 3 times or so for 2 weeks, as a result the websites were inaccessible for hours and since there is nobody to reboot the server for hours; the websites keep hanging until the DB host is restarted ;;;;

To work-around this I came with the idea to write a tiny shell script to check if host2 is ping-able in order to assure the Database host is not down and then if script determines host2 (mysql) host is down it changes wp-config.php (set to use host2) to a wp-config.php (which I have beforehand configured to use) host1.

Using the script is a temporary solution, since I have to actually find the real hang-up causing troubles, but at least it saves me long downtimes. Here is a download link to the script I called change_blog_db.sh .
I've configured the script to be run on the Apache node (host1) via a crontab calling the script every 10 minutes, here is the crontab:
 

*/10 * * * * /usr/sbin/change_blog_db.sh > /dev/null 2>&1

The script is written in a way so if it determins host2 is reachable a copy of wp-config.php and Joomla's configuration.php tuned to use host2 is copied over the file config originals. In order to use the script one has to configured the head variables script section, e.g.:

host_to_ping='192.168.0.2';
blog_dir='/var/www/blog';
blog_dir2='/var/www/blog1';blog_dir3='/var/www/joomla';
notify_mail='hipo@pc-freak.net';
wp_config_orig='wp-config.php';
wp_config_localhost='wp-config-localhost.php';
wp_config_other_host='wp-config-192.168.0.2.php';
joomla_config_orig='configuration.php';
joomla_config_other_host='configuration-192.168.0.2.php';

You will have to manually prepare;;;

wp-config-localhost.php, wp-config-192.168.0.2.php ,configuration-192.168.0.2.php, wp-config-localhost.php to be existing files configured to with proper host1 and host2 IP addresses.
Hope the script will be useful to others, experiencing database downtimes with WordPress or Joomla installs.
 

Negative impact of Cell Phones (GSM) use on individual and society

Monday, June 25th, 2012

Negative impact of Cell Phones GSM on individual and society

We all live in an age, where cell-phone communication has become a standard part of our daily lives. As with everything new adopted in basic human life. GSM tool inclusion in our life had a severe impact on both individuals and in summary to whole society groups and nations.

The benefits out of having an instant “channel” for communication to anyone else in the world are indoubtfully numerous. However as present tosicety is learned to mostly thing in one direction, most people didn’t have a clear understanding on the negative impact of this little communicators on our mind body and soul.

1.; Negative impact of mobile phones on body level

Whenever we talk over the phone especially when picking up incoming calls or initiating out-going ones, the GSM device has to connect to the closest network cell “dial up” and wait for initialization of remote or local connection. The levels of radiation waves during the two mobiles connects up is higher. Therefore if one moves the phone near his ear listening for the status of call the amount of radiation that enters our brains is slightly higher. The extra-radiation whether mobiles are connecting is also few times more whether our phone is ringning, hence it is unhealthy to put the phone near our ear before we press the Answer Call button.

2.;; Negative effect of continuous mobile phones use on human brain

Knowing about the increased radiation on connection initialization thanksfully one can protect himself by simply not putting the mobile headset near ear on call initialization. Though this “problem” can be partially solved, next comes the health brain damage (tumours) which according to some researches are higher among people who do frequentlong phone call conversations. In long phone calls the brain is exposed for a longer time to the flowing waves making the peer to peer call possible. According to some medical researches, a long and frequent phone calls could be a reason not only for brain cancers but also other misfunctions or damages in normal brain cells functioning.

3.;;; The bad impact of Cell Phones on nervous system

Another health issue which the daily phone use and the constant exposure to mobile network cells radio frequency radiation affects generally our nervous system.

Unexpected phone calls early in morning or late at night are a cause for increased bodily stress and even the fear sometimes for an incoming phone call are a cause for many types of neurological disorders diagnosed by psychiatrists.
Even when we sleep at night the mobile phone periodically connects to the nearest mobile cell generating some almost undetectable “waves contamination”. This constant waves air flow caused by the mobile network cells positioned all around cities is not usual thing for our bodies. This also has some influence on our nervous system as the nervous sysm tends to be a bit more alert because of the waves constantly passing the body. The natural reaction of our bodies nerves is to try to balance itself. As nervous system of different people is not equal some people’s nervous system is more prone to having difficulties to balance the disbalance created by the increased number of mobile air waves.
The result of this to many people is in increased sleeplessnes and hardships to get asleep (according to research taken place in American Academy of Sleep Medicine.).

4.;;;; Lost of social and ethical behaviour in people

There is lately observed a huge shift from a face to face communication to peer to peer (p2p) on the phone. The cellphones breeds a culture of socially group detached people (the communication over phone is rarely a conference) but rather consists of communication between two persons (peer to peer). The p2p communication is not only a primary mean of communication of people exposed to heavy phone use. p2p Communication is a primary communication in Skype, Google Talk and mostly all modern available communication medias and softwares.

As more and more people spend nowdays more time on the mobile than in real communication, this makes them introverted and isolated and increases the inability to deal with real human f2f interaction. In other words continuous phone use re-trains us to communicate with others via the mobile. Besides that according to numerous researches about 40 to 50% of visual communication whether a phone call is used is lost (this also makes negotiation or expressing over phone harder and at least twice longer than in real communication).

The influence of the decreased social abilities cause of the phone use has also an impact on ethical behaviour of people too. The increased lost of communication abilities makes even daily real communication vague and lacking accepted social norms and ethical values. Next to that comes the huge problem of over-simplification of communication. As the line communication over the phone loose half of the communication as well as sometimes there are quality of voice over the network interferences. People are doing their best to simplify the communication adopting short command like like phrases and talking in a slang.

5.;;;;; Addiction to mobile phone use

The use of mobile phone often has a short beep sounds, whether you work on the keyboard receive a phone call or look for some mobile functionality staring at the screen. We’re wearing the mobile everywhere with us so often we do check the mobile screen quite un-consciously (by addiction). Checking the mobile screen to see what time is it has become almost an instinct and an automated learned behaviour.

The continous use of mobile phones makes many people mobile addicts. There are huge amount of people I’ve observed who speaks everyday for few hours (whether everytime they feel lonely they call someone in order not to feel lonely). The mobile phone addiction in youngsters is slighly higher than in adults. Probably the most mobile dependent addicts are kids who were given a mobile to use since there very early years.
Anyways there are tons of adults nowdays who cannot even think to be able to live without mobile and even cannot understand: how can anyone think that life could be possible without a cell phone. This kind of thinking is a direct trait showing an addiction and dependency on the phone such people have.

Color Psychology – Color Mind Programming or how big companies boost their sales and make up your mind

Thursday, June 21st, 2012

Colors Programming Color mind Programming, how big companies boost their sales and make up your mind

As I've pointed earlier there is plenty of "secretly" kept and less known by public research on how colors influence us daily. The biggest companies are heavily taking advantage of what is found and known for colors impact on our minds (psyche). Actually there is a whole branch in psychology which deals with impact of colors perception on us.Besides companies, many modern governments are well aware of the many facts on how citizens percept colors and use this in color 'installment' in government offices and government institutions.

There is no universal knowledge on how colors completely affect us as every human on earth is very unique and saying this or that color has this or that impact on indivirual or group is not 100% accurate. However there are general traits nowdays formed especially with globalization and unification of TV ads and big companies corporate image, a unification started on how different nationality people perceive colors.

Nowdays in developed countries there are more and more people who perceive certain colors in similar fashion. Therefore every serious top marketer should carefully study colors and their relation with ancient time people believes and understanding on what each of the 'rainbow' colors symbolize. Most likely because there is no completely unified understanding of colors between various individuals may companies like Google and Microsoft started using all the rainbow colors in their basic company logos and branding for more on this topic please check my previous blog post Color trick Microsoft and Google use to keep their users loyal

Another large industry area, where color programming is very heavy is Computer and Video Games. You certainly still remember large portions of the games like Sega’s Sonic the HendgeHog or Mario Super Bros. or even the old arcade machines with games like Punisher or Cadillacs and Dinosaurs, Street Fighter etc.
All this old arcade games have a big portion of Color programming embedded in and this is one of the main reasons we remember them for a long time and playing them evoked such a strong feelings in youth.

This trend of using colors to make up our minds is being observed for many other physical goods as well as is starting to get more and more heavy adoption by websites branding on the internet.
Actually those with most succesful businesses on the internet have already integrated some kind of color programming scheme. An example for this would be the Internet top domain names seller GoDaddy. The have adopted a green scheme as a primary color combined with some other ones to create in the customer a feeling of ecology, naturality, peace and solitude.

The study of color programming is one major field to be known by anyone truly willing to understand why certain big store chainslike Carrefour, Lidl, Billa, MediaMarkt – in western europe or TechnoMarket, TechnoPolis (MediaMarkt copied tech equipment by shops here in Bulgaria) are decorated inside the way they are. I personally didn't like the concept of color programming since from Spiritual point of view it is a big evil. Trying to manipulate people perception to do something you would like to in general is very evil from spiritual point of view. A mixture of rainbow colors in a natural environment for example flowers in the wood or wild mountain place is one thing, but making it artificial and placing it in certain pre-desired order is totally another. Besides that the colors in the natural environment are natural and therefore the impact on us even if colorful is very much better than if it is done with a certain intention like in the big supermarkets stores, fast just food companies – McDonalds, Burger King etc.

The research on color mind influcence – Color mind programming is a controversial science. Nowdays many big businesses however use this as a granted science, even whole business sects with some mambo-jambo believes universities, children garden and schools in modern countries have employed the use of some type of color programming aiming to influence their pupils, students (organizational members – you call it).
Color mind programming and heavy use on advertisements on the TV, the Internet, Stores and mostly everywhere are however starting to took their tolls. The high increase in mental problems and dumbness in developed and some undeveloped countries as well as the increased number of people who go insane because of too much color programming is reality. The believe that mental programming is one of the ultimate tools to influence somebody and push him to do things you want like consome more of a product or generally consume (buy) more goods creates another severe issue it makes people to constantly over-consume (eat more than the body needs) and this increases the number of over-consumption evoked diseases …

But color programming doesn't stop with just the material (physical) surrounding world it is a concept highly employed in online based marketing. Online business is seen on so many top used websites, social networks like take for instance (facebook). It is so spread that even the software primary vendors like Microsoft, search engines Google Inc. have already heavily employed the color programming as a basis of their products.

There is another reason why most vendors nowdays issue their physical or 'virtual' products so colorful using all the colors of the rainbow. The reason is the fact that as a kids through animation, cartoons, toys and surrounding environment we have been exposed already even from our very youth age to a kind of color programming through kids toys we've been given by our parents). Hence the young years color programming became a basis for a future time color programming. The colorfulness of our kids years are already sub-consciously stored in our minds, so almost naturally there is a feeling of joy to pop-up once we see something childishly colorful.
 

SWITCH OFF your Mobile Phone and TV at night to save energy!!!

Thursday, June 7th, 2012

TURN OFF YOUR MOBILE PHONE AT NIGHT to SAVE ENERGY and MONEY

We’re constantly being said to reduce energy consupmtion, they sell us new bulbs to save energy, new TVs with energy saving. The newer the computer equipment microwaves or whatever home electrical equipment we buy the more it is said to be saving energy.

So far so good it is true we can reduce energy consumption by producing gadgets which consume less. However there are also another approach to the “green problem” which we never are said about.

It is rather simply instead of saving energy on technology base, we can save energy on physical base. One simple thing to do to save energy with no need to spend money on latest advacement gadgets is to simply make it the old school way.

a -= Learn to switch off your lamps and home equipment whenever its not necessery

If you’re about to go to sleep, you can simply switch off the mobile and use a mechanical clock to wake you up on the morning, this way you have 3 benefits.

1; Less energy will be discharged by the mobile in the time you’re not awake, so you don’t need to charge so frequently the battery and therefore you will draw less energy from the Electrical network hence saving energy.

2; You will not be radiated with a bit less radiation produced by the Mobile phone in order to stay connected to the GSM local located cell.

Though the good this does will not be dramatical it for sure will be better for your health than if the mobile is switched on the whole night.

3; You will not be awakened in morning by some crazy person who just decided to call you early in the morning.
Often this morning unexpected and desired phone calls make you jump off the bed rapidly and hence giving a large dose of stress to your organizm.

-=- Of course switching off the mobile has some disadvantages if you can receive a crucial phone calls during all time of day or night you can’t afford to simply switch off the mobile, this is however not true for most people who work in an OFF-ICE.People working in offices can simply wake up at a scheduled time, get a shower do their morning hygiene and jump to a car or bus to the office so the need for having the mobile switched ON at night is not really needed.

Of course thinking in the same direction, it is logical that switching off the computer earlier when not needed, the wireless home router or the TV is another place from where a huge energy savings can be achieved.

If large amount of people re-learn their energy in-efficient habits to be more energy cautios a HUGE amounts of energy can be saved. This of course can have a positive impact on the monthly energy bills and hence can save you money in monthly expenses.

The TV is surely another big energy draining source, many people have the habit to sleep with a Television switched on. Besides this has a negative impact on the conscious since vast amounts of information are being stored and processed by the conscious and unconscious mind, also the lights emitted from the TV screen prevents the persons body to not have a pieceful rest.

Its rather stupid that companies are constantly ranting on how they improve their products to be energy friendly but they don’t invest even a penny to educate the masses that energy saving does not only depend on how good the technology is produced to save energy but also on how much the people are educated how to use the technology with energy saving in mind.Probably there are plenty of other ways a households can change their habits to save energy. I’ll be glad to hear some other suggestions ,,,

How to disable ACPI (power saving) support in FreeBSD / Disable acpi on BSD kernel boot time

Tuesday, May 15th, 2012

FreeBSD disable ACPI how ACPI Basic works basic diagram

On FreeBSD the default kernel is compiled to support ACPI. Most of the modern PCs has already embedded support for ACPI power saving instructions.
Therefore a default installed FreeBSD is trying to take advantage of this at cases and is trying to save energy.
This is not too useful on servers, because saving energy could have at times a bad impact on server performance if the server is heavy loaded at times and not so loaded at other times of the day.

Besides that on servers saving energy shouldn't be the main motivator but server stability and productivity is. Therefore in my personal view on FreeBSD used on servers it is better to disable complete the ACPI in order to disable CPU fan control to change rotation speeds all the time from low to high rotation cycles and vice versa at times of low / high server load.

Another benefit of removing the ACPI support on a server is this would probably increase the CPU fan life span and possibly prevent the CPU to be severely heated at times.

Moreover, some piece of hardware might have troubles in properly supporting ACPI specifications and thus ACPI could be a reason for unexpected machine hang ups.

With all said I would recommend to anyone willing to use BSD for a server to disable the ACPI (Advanced Configuration and Power Interface), just like I did.

Here is how;

1. Quick review on how ACPI is handled on FreeBSD

acpi support is being handled on FreeBSD by a number of loadable kernel modules, here is a complete list of all the kernel modules dealins with acpi:

freebsd# cd /boot
freebsd# find . -iname '*acpi*.ko'
./kernel/acpi.ko
./kernel/acpi_aiboost.ko
./kernel/acpi_asus.ko
./kernel/acpi_fujitsu.ko
./kernel/acpi_ibm.ko
./kernel/acpi_panasonic.ko
./kernel/acpi_sony.ko
./kernel/acpi_toshiba.ko
./kernel/acpi_video.ko
./kernel/acpi_dock.ko

By default on FreeBSD, if hardware has some support for ACPI the acpi gets activated by acpi.ko kernel module. The specific type of vendors specific ACPI like IBM, ASUS, Fujitsu are controlled by the respective kernel module from the list …

Hence, to control if ACPI is loaded or not on a FreeBSD system with no need to reboot one can use kldload, kldunload module management BSD cmds.

a) Check if acpi is loaded on a BSD

freebsd# kldstatkldstat | grep -i acpi
9 1 0xc9260000 57000 acpi.ko

b) unload kernel enabled ACPI support

freebsd# kldunload acpi

c) Load acpi support (not the case with me but someone might need it, if for instance BSD is running on laptop)

freebsd# kldload acpi

2. Disabling ACPI to load on bootup on BSD

a) In /boot/loader.conf add the following variables:

hint.acpi.0.disabled="1"
hint.p4tcc.0.disabled=1
hint.acpi_throttle.0.disabled=1


b) in /boot/device.hints add:

hint.acpi.0.disabled="1"

c) in /boot/defaults/loader.conf make sure:

##############################################################
### ACPI settings ##########################################
##############################################################
acpi_dsdt_load="NO" # DSDT Overriding
acpi_dsdt_type="acpi_dsdt" # Don't change this
acpi_dsdt_name="/boot/acpi_dsdt.aml"
# Override DSDT in BIOS by this file
acpi_video_load="NO" # Load the ACPI video extension driver

d) disable ACPI thermal monitoring

It is generally a good idea to disable the ACPI thermal monitoring, as many machines hardware does not support it.

To do so in /boot/loader.conf add

debug.acpi.disabled="thermal"

If you want to learn more on on how ACPI is being handled on BDSs check out:

freebsd# man acpi

Other alternative method to permanently wipe out ACPI support is by not compiling ACPI support in the kernel.
If that's the case in /usr/obj/usr/src/sys/GENERIC make sure device acpi is commented, e.g.:

##device acpi

 

Possible way to Improve wordpress performance with wp-config.php 4 config variables

Tuesday, March 6th, 2012

Wordpress improve performance wp-config.php logo chromium effect GIMP

Nowdays WordPress is ran by million of blogs and websites all around the net. I myself run wordpress for this blog in general wordpress behaves quite well in terms of performance. However as with time the visitors tend to increase, on frequently updated websites or blogs. As a consequence, the blog / website performance slowly starts to decrease as result of the MySQL server read / write operations creating I/O and CPU load overheads. Buying a new hardware and migrating the wordpress database is a possible solution, however for many small or middle size wordpress blogs en sites like mine this is not easy task. Getting a dedicated server or simply upgrading your home server hardware is expensive and time consuming process… In my efforts to maximize my hardware utilization and increase my blog decaying performance I've stumbled on the article Optimize WordPress performance with wp-config.php

According to the article there are 4 simple wp-config.php config directvies useful in decreasing a lot of queries to the MySQL server issued with each blog visitor.

define('WP_HOME','http://www.yourblog-or-siteurl.com');
define('WP_SITEURL','http://www.yourblog-or-siteurl.com');
define('TEMPLATEPATH', '/var/www/blog/wp-content/themes/default');
define('STYLESHEETPATH', '/var/www/blog/wp-content/themes/default');

1. WP_HOME and WP_SITEURL wp-config.php directvies

The WP_HOME and WP_SITEURL variables are used to hard-code the address of the wordpress blog or site url, so wordpress doesn't have to check everytime in the database on every user request to know it is own URL address.

2. TEMPLATEPATH and TEMPLATEPATH wp variables

This variables will surely improve performance to Wodpress blogs which doesn't implement caching. On wp install with enabled caching plugins like WordPress Super Cache, Hyper Cache or WordPress Db Cache is used, I don't know if this variables will have performance impact …

So far I have tested the vars on a couple of wordpress based installs with caching enabled and even on them it seems the pages load faster than before, but I cannot say this for sure as I did not check the site loading time in advance before hardcoding the vars.

Anyways even if the suggested variables couldn't make positive impact on performance, having the four variables in wp-config.php is a good practice for blogs or websites which are looking for extra clarity.
For multiple wordpress installations living on the same server, having defined the 4 vars in different wordpress seems like a good idea too.

Facebook and Youtube Culture has a negative impact on people in young years development and teenagers

Tuesday, December 13th, 2011

Facebook and Youtube helps young people get stupid

Facebook and Youtube has become for just a few years a defacto standard service for 80% of computer users in our age.
This is true and it seems there is growing tendency for people to adopt new easy to use services and a boom in the social networks.
We’ve seen that with the fast adoption of the anti-human freedom program Skype , the own privacy breaching FaceBook as well as the people interests tracking service YouTube.

We’ve seen similar high adoption rates in earlier times as well with the already dying (if not dead MySpace), with the early yahoo mail boom etc and in even earlier times with the AltaVista search engine use.
However this time it appears Youtube and FaceBook are here to stay with us and become standard online services for longer times …
Many people who work in office all day staring in a computer screen as well as growing teenagers and practically anyone in the developed and the development world is using those services heavily for (in between 5 to 10 hours a day or more). The Software as a Service users spends approximately half of their time spend on the internet in Youtube or and Facebook.

Its true Youtube can be massively educative with this global database of videos on all kind of topics and in some cases facebook can be considered helpful in keeping in touch people or keeping a catalog of pictures easily accessible from everywhere, however when few services becomes more used and influential than other provided services on the internet this makes these services harmful to the communities and destroyes cultures. The concentration of most of the human popuplation who uses high technologies around few online services creates a big electronic monopoly. In other words the tendency, we see of amalgamation of businesses in real world (building of big malls and destroyment of small and middle sized shops is being observed in the Internet space.

Besides that Facebook and Youtube and Twitter are highly contrary to the true hacker spirit and creates a big harm for intellectuals and other kind of tight and technical community culture by creating one imaginative casual disco culture without any deepness of thought or spirit.

Its observable that most of the people that are heavily using those services are turning into (if not exaggerate) a brainless consumer zombies, a crowd of pathless people who watch videos and pictures and write meaningless commentaries all day long.

You have as a result a “unified dumbness” (dumbness which unifies people).

Even if we can accept the grown and fully formed character people are aware of the threats of using Youtube or Facebook, this is definitely not the case with the growing people which are still in a process of building personality and personal likings.
The harmful resuls that the so called Social networks create can be seen almost everywhere, most of the cafeterias I visit the bar tender uses facebook or youtube all da long, most of random people I see outside in a coffee or university or any public institution where internet access is available they are again in Youtube and Facebook. The result is people almost did not use the Net but just hang around in those few services wasting network bandwidth and loading networks and computer equipment and spending energy for nothing. The wasteful computer and Internet deepens the ecologic problems as energy is spend on nonsense and not goal oriented tasks but on “empty” false entertainment.
Hence the whole original idea of internet for many is changed and comes to few words ( Skype, Youtube, Facebook etc.

Besides that youngsters instead of reading some classical valuable books, are staring in the computer screen most of their cognitive time at only this few “services” and are learned to become more a consumers than self opinion thinkers and inventors.
I have not lately met any growing real thinking man. I’ve seen already by own experience the IQ level of younger generations than mine (I’m 28) is getting downer and downer. Where I see as a main cause the constant interaction with technology built in a way to restrict, a consumers technology so to say.
Facebook and Youtube puts in young and growing man’s mind, the wrong idea that they should be limited choice people always praising what is newest and brightest (without taking in consideration any sight effects). These services lead people to the idea that one should always be with the crowds and never have a solid own opinion or solid state on lifely matters. As said own opionion is highly mitigated especially in facebook where all young people try to look not what they really are but copy / paste some trendy buzz words, modern style or just copying the today’s hearoes of the day. This as one can imagine prevents a person of getting a strong unique self identity and preference on things.

Many of the older people or computer illiterates can hardly recognize the severe problems, as they’re not aware on the technical side of things and does not realize how much security compromising as well as binding the constant exposure to those online hives are.
The purpose of this small post is hence just a small attempt to try to raise up some awareness of the potential problems, we as society might face very soon if we continue to follow the latest buzz trends instead of stop for a moment have a profound think on what is the moral consequences of giving so much power on Internet medias like Facebook and Youtube? …

How to disable IPv6 on Debian / Ubuntu / CentOS and RHEL Linux

Friday, December 9th, 2011

I have few servers, which have automatically enabled IPv6 protocols (IPv6 gets automatically enabled on Debian), as well as on most latest Linux distribituions nowdays.

Disabling IPv6 network protocol on Linux if not used has 2 reasons:

1. Security (It’s well known security practice to disable anything not used on a server)
Besides that IPv6 has been known for few criticil security vulnerabilities, which has historically affected the Linux kernel.
2. Performance (Sometimes disabling IPv6 could have positive impact on IPv4 especially on heavy traffic network servers).
I’ve red people claiming disabling IPv6 improves the DNS performance, however since this is not rumors and did not check it personally I cannot positively confirm this.

Disabling IPv6 on all GNU / Linuces can be achieved by changing the kernel sysctl settings net.ipv6.conf.all.disable_ipv6 by default net.ipv6.conf.all.disable_ipv6 equals 1 which means IPv6 is enabled, hence to disable IPv6 I issued:

server:~# sysctl net.ipv6.conf.all.disable_ipv6=0

To set it permanently on system boot I put the setting also in /etc/sysctl.conf :

server:~# echo 'net.ipv6.conf.all.disable = 1 >> /etc/sysctl.conf

The aforedescribed methods should be working on most Linux kernels version > 2.6.27 in that number it should work 100% on recent versions of Fedora, CentOS, Debian and Ubuntu.

To disable IPv6 protocol on Debian Lenny its necessery to blackist the ipv6 module in /etc/modprobe.d/blacklist by issuing:

echo 'blacklist ipv6' >> /etc/modprobe.d/blacklist

On Fedora / CentOS there is a another universal “Redhat” way disable IPv6.

On them disabling IPv6 is done by editting /etc/sysconfig/network and adding:

NETWORKING_IPV6=no
IPV6INIT=no

I would be happy to hear how people achieved disabling the IPv6, since on earlier and (various by distro) Linuxes the way to disable the IPv6 is probably different.
 

Alto to stop Iptables IPV6 on CentOS / Fedora and RHEL issue:

# service ip6tables stop

# service ip6tables off

How to convert Postscript files to PDF on Debian GNU / Linux with ps2pdf

Saturday, December 3rd, 2011

convert ps to pdf linux,Free as in Freedom book cover - Richard Stallman GNU and Free Software Father

I’m currently reading Free as in Freedom (2.0) R. Stallman and the Free Software Revolution
The book includes a reference to Eric S. Raymond ‘s famous The Cathedral and the Bazaar which does makes a point about the important of Open Source . I’ve read the The Cathedral and the Bazaar paper some very long time ago (in my young days so to say) and hence I couldn’t resemble much of the document so I jumped in after the footnote in the FAIF book and decided to take a quick look on The Cathedral and the Bazaar once again to bring up some memories. I was stunned to find the paper is available in many formats but officially not included in PDF . Since i’m a GNU / Linux user I’ve never managed to get into the habit to read postscript documents which from modern day stand point are also already a bit of obsolete and therefore I found it as a wise idea to convert and mirror the POSTSCRIPT (PS) version of the document to PDF on pc-freak.net

Happily the ps2pdf command to convert the ps to pdf on my debian gnu / linux is really easy:

ps2pdf cathedral-and-the-bazaar-Eric_Raymond.ps Cathedral-and-the-bazaar-Eric_Raymond.pdf

ps2pdf is part of the ghostscript deb package, so if you can’t find the program you will need to have it installed with apt-get first.

By the way the Postscript file is easily readable using my default gnome PDF reader evince , but anyways I converted and mirrored the paper for all those windows users who might like to take a look at the document in PDF.
I’ve also made a mirror of the original Cathedral and the Bazaaar postscript document here , for all those who want to check out The PDF version of the Cathedral and the Bazaaar is for download here

Even though the “open source” movement is an interesting idea and it had some major impact on the development of some free software the idiology of open source which was very much influenced by this document is very weak compared to the philosophy Richard Stallman indcuded as of the great need of the software to be free.

To be honest looking back in time for a long time being a Linux user I did not make any distinguishment between “Free Software” concept and “Open Source”, even worser I considered to evangelize on Open Source not realizing that initially what attracted me to free software was the idiology of open source and not the real values on which ground free software is built.
This kind of miss understanding between perception of “open source” and “free software” I got and spread for years now I fully realize and I seem like when I red back then The Cathedral and the Bazaar document I didn’t looked any critical at the document but it had a major, I would say “bad” impact on my idiology on software for a long time. So for all those who had not checked it it’s worthy checking but only in case if one fully understands Richard Stallman’s concept of Free Software, without this understanding one can easily slip into the wrong believe (just like me back in thme) that open source is the same as free software. Even though open source can be free software it is not presumably that an open source is free software and that it guarantees that the published source will be free. But I’ll stop now as I slept away from my goal of the article to just log here how a convertion of postscript to pdf on gnu / linux is done.
Just to close up this article I warmly recommend on all people interested into hacking and the history of Free operating systems and Free software as FreeBSD and GNU / Linux the Free as in Freedom (2.0) book ! Its truly a remarkable and great inspirational reading for all people like me involved into free software realm of ICT.