Dim the Lights

In most of the devices, including cellphones, the display is the biggest culprit when it comes to reduced battery life. A brightly lit laptop won’t really help you get through a whole workday. The best solution to this problem is to dim the screen as much as possible. If, in certain cases like movie-watching or reading you need a bright display, you can turn the brightness up for that period and them dim the screen back when you’re finished.

Kill the Slowpokes

It’s not just the display that hurts the battery, it’s also those CPU-hogging programs that make you reach out for the charger sooner than expected. That said, it’s not always easy for a user to spot that the CPU is under a load. It takes a real slowdown or freezing to realize that the program has become a mess and needs to be killed.

Don’t worry yet, as you can always keep an eye on your CPU or RAM by using any of the following methods:

1. Take a look at the system monitor if you feel the slightest of difference in performance. From there, you can kill any misbehaving task.

2. Ubuntu users can install the System Load Indicator from a ppa, which, once installed, will let you take a look at the performance right from the indicator menu. To install, go to the terminal (Ctrl+Alt+T) and paste/type in the following commands.

sudo add-apt-repository ppa:indicator-multiload/stable-daily

sudo apt-get update && sudo apt-get install indicator-multiload

Power Management

The computer’s power management scheme is one of the most important factors that decide the fate of your battery. In the power management settings window, always make sure you choose a balanced plan that helps you get through a whole workday without looking for an adapter. Another great way to take advantage of this setting is by making sure that the laptop goes into suspend mode as soon as the lid is closed. Though, it might not be a suitable setting for folks who are a tad impatient, it still is one of the most effective ways of saving battery life. To access the power management settings in Ubuntu, open the Dash (Super/Windows key) and type in the word “Power” without quotes.

Hibernate over Suspend

If, instead of shutting down your laptop, you put it on suspend mode, always make sure you’re connected to a charger. If not, then put the computer in hibernate mode and go for a nice nap. That way, neither would you lose any precious battery life nor would you lose your current work.

Keep It Cool

Most of the battery loss also occurs due to overheating laptops. The overheating issue is something that affects a lot of laptops. To remedy that problem, simply use a laptop cooling pad, a simple accessory that saves your computer from overheating. It’s also a good idea to keep an eye on the temperature; to do that, simply install the system monitor indicator that comes with various temperature sensors.

sudo add-apt-repository ppa:alexeftimie/ppa

sudo apt-get update && sudo apt-get install indicator-sysmonitor

Or, if all you want is a simple hardware sensor, then try out the following indicator applet:

sudo add-apt-repository ppa:alexmurray/indicator-sensors

sudo apt-get install indicator-sensors

Update Update Update

Finally, always remember to update your computer. The Linux kernel is continuously improving, and so are the distributions. In Ubuntu 12.04 for example, users will get to see an improved support for battery life. So, make sure you don’t ignore your computer when it badgers you to give it a big update.

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• how to improve the battery life in fedora (1)

I’m using Debian on daily basis, and everybody that had even little of experience with Debian should already be aware about the existence of the handy:
/etc/modules file.
On Debian to enable a certain kernel module to load up on Linux boot, all necessery is to just place the kernel module name in /etc/modules.

For example loading the tun tunneling kernel module I issue the command:

debian:~# echo tun >> /etc/modules


I wondered if CentOS, also supports /etc/modules as it was necessery now to add this tun module to load up on CentOS’s boot.
After a bit of research I’ve figured out CentOS does not have support for adding modules names in /etc/modules , anyhow after consulting CentOS documentation on  http://www.centos.org , I found CentOS and RHEL use /etc/rc.modules instead of Debian’s /etc/modules to load up any custom kernel modules not loaded by default during system boot.

Therefore instructing the RHEL Linux to load up my desired tun module in kernel on next boot was as easy as executing:

[root@centos ~]# echo 'modprobe tun' >> /etc/rc.modules
[root@centos ~]# chmod +x /etc/rc.modules


Now on next boot CentOS will load up the tun module in kernel. Achiving the same module load up is also possible through /etc/rc.local , but it’s not recommended way as /etc/rc.local would load up the kernel module after all of the rest init boot scripts complete and therefore will load up the module slightly later, at the final boot stage.

I’m aware of the existence of Hardware Watchdog devices, which are capable to detect if a server is hanged and auto-restart it, however the servers I administrate does not have Hardware support for Watchdog timer.

Thankfully there is a free software project called Watchdog which is easily configured and mitigates the terrible downtimes caused every now and then by a server crash and respective delays by tech support in Data Centers.

I’ve recently blogged on the topic of Debian Linux auto-restart in case of kernel panic , however now i had to configure watchdog on some dozen of CentOS Linux servers.

It appeared installation & configuration of Watchdog on CentOS is a piece of cake and comes to simply following few easy steps, which I’ll explain quickly in this post:

1. Install with yum watchdog to CentOS

[root@centos:/etc/init.d ]# yum install watchdog
…

2. Add to configuration a log file to log watchdog activities and location of the watchdog device

The quickest way to add this two is to use echo to append it in /etc/watchdog.conf:

[root@centos:/etc/init.d ]# echo ‘file = /var/log/messages’ >> /etc/watchdog.conf
echo ‘watchdog-device = /dev/watchdog’ >> /etc/watchdog.conf

3. Load the softdog kernel module to initialize the software watchdog via /dev/watchdog

[root@centos:/etc/init.d ]# /sbin/modprobe softdog

Initialization of softdog should be indicated by a line in dmesg kernel log like the one above:

[root@centos:/etc/init.d ]# dmesg |grep -i watchdog
Software Watchdog Timer: 0.07 initialized. soft_noboot=0 soft_margin=60 sec (nowayout= 0)

4. Include the softdog kernel module to load on CentOS boot up

This is necessary, because otherwise after reboot the softdog would not be auto initialized and without it being initialized, the watchdog daemon service could not function as it does automatically auto reboots the server if the /dev/watchdog disappears.

It’s better that the softdog module is not loaded via /etc/rc.local but the default CentOS methodology to load module from /etc/rc.module is used:

[root@centos:/etc/init.d ]# echo modprobe softdog >> /etc/rc.modules
[root@centos:/etc/init.d ]# chmod +x /etc/rc.modules

5. Start the watchdog daemon service

The successful initialization of Softdog in step 4, should have provided the system with /dev/watchdog, before proceeding with starting up the watchdog daemon it’s wise to first check if /dev/watchdog is existent on the system. Here is how:

[root@centos:/etc/init.d ]# ls -al /dev/watchdogcrw——- 1 root root 10, 130 Aug 10 14:03 /dev/watchdog

Being sure, that /dev/watchdog is there, I’ll start the watchdog service.

[root@centos:/etc/init.d ]# service watchdog restart
…

Very important note to make here is that you should never ever configure watchdog service to run on boot time with chkconfig. In other words the status from chkconfig for watchdog boot on all levels should be off like so:

[root@centos:/etc/init.d ]# chkconfig –list |grep -i watchdog
watchdog 0:off 1:off 2:off 3:off 4:off 5:off 6:off

Enabling the watchdog from the chkconfig will cause watchdog to automatically restart the system as it will probably start the watchdog daemon before the softdog module is initialized. As watchdog will be unable to read the /dev/watchdog it will though the system has hanged even though the system might be in a boot process. Therefore it will end up in an endless loops of reboots which can only be fixed in a linux single user mode!!! Once again BEWARE, never ever activate watchdog via chkconfig!

Next step to be absolutely sure that watchdog device is running it can be checked with normal ps command:

[root@centos:/etc/init.d ]# ps aux|grep -i watchdog
root@hosting1-fr [~]# ps axu|grep -i watch|grep -v greproot 18692 0.0 0.0 1816 1812 ? SNLs 14:03 0:00 /usr/sbin/watchdog
root 25225 0.0 0.0 0 0 ? ZN 17:25 0:00 [watchdog]

You have probably noticed the defunct state of watchdog, consider that as absolutely normal, above output indicates that now watchdog is properly running on the host and waiting to auto reboot in case of sudden /dev/watchdog disappearance.

As a last step before, after being sure its initialized properly, it’s necessery to add watchdog to run on boot time via /etc/rc.local post init script, like so:

[root@centos:/etc/init.d ]# echo ‘echo /sbin/service watchdog start’ >> /etc/rc.local

Now enjoy, watchdog is up and running and will automatically restart the CentOS host.

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• config vsftpd in centos 6 2 (1)
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On a VMware ESXi 5.0 host, how can I check if fiber storage adapters are properly connected to the fiber switch/SAN, i.e. if the fiber link is up?

Solution:

This information is shown nowhere in the vSphere Client, and there is no command-line tool to check it, either.

The only way to verify if a fiber link is up is to access the ESXi shell and go to /proc/scsi/your_hba_driver (in my case, /proc/scsi/qla2xxx); there is a (virtual) file there for each fiber port, and the contents of these files include one of the following:

For an active link:

Host adapter:Loop State = <READY>, flags = 0xaa68
Link speed = <8 Gbps>

For an inactive link:

Host adapter:Loop State = <DEAD>, flags = 0x1a268
Link speed = <Unknown>

If you are a system administrator, you have probably wondered at least once how to configure your Linux server to automatically reboot itself if it crashes, is going through a mass CPU overload, e.g. the server load average “hits the sky”.

I just learned from a nice article found here that there is a kernel variable which when enabled takes care to automatically restart a crashed server with the terrible Kernel Panic message we all know.

The variable I’m taking about is kernel.panic for instance kernel.panic = 20 would instruct your GNU Linux kernel to automatically reboot if it experiences a kernel panic system crash within a time limit of 20 seconds.

To start using the auto-reboot linux capabilities on a kernel panic occurance just set the variable to /etc/sysctl.conf

debian-server:~# echo 'kernel.panic = 20' >> /etc/sysctl.conf

Now we will also have to enable the variable to start being use on the system, so execute:

debian-server:~# sysctl -p

There you go automatic system reboots on kernel panics is now on.
Now to further assure yourself the linux server you’re responsible of will automatically restart itself on a emergency situation like a system overload I suggest you check Watchdog

You might consider checking out this auto reboot tutorial which explains in simple words how watchdog is installed and configured.
On Debian installing and maintaining watchdog is really simple and comes to installing and enabling the watchdog system service, right afteryou made two changes in it’s configuration file /etc/watchdog.conf

To do so execute:

debian-server:~# apt-get install watchdog
debian-server:~# echo "file = /var/log/messages" >> /etc/watchdog.conf
debian-server:~# echo "watchdog-device = /dev/watchdog" >> /etc/watchdog.conf


Well that should be it, you might also need to load some kernel module to monitor your watchdog.
On my system the kernel modules related to watchdog are located in:

/lib/modules/2.6.26-2-amd64/kernel/drivers/watchdog/
If not then you should certainly try the software watchdog linux kernel module called softdog , to do so issue:

debian-server:~# /sbin/modprobe softdog


It’s best if you load the module while the softdog daemon is disabled.
If you consider auto loadig the softdog software watchdog kernel driver you should exec:

debian-server:~# echo 'softdog' >> /etc/modules


Finally a start of the watchdog is necessery:


debian-server:~# /etc/init.d/watchdog start
Stopping watchdog keepalive daemon....
Starting watchdog daemon....


That should be all your automatic system reboots should be now on!

This function parses a URL and returns an associative array containing any of the various components of the URL that are present. It is important to note that parse_url does not validate the given URL, it simply breaks it up into parts. Partial URLs are also accepted, and whilst parse_url tries its best to parse them correctly, it may return -1 if the URL provided is too malformed.

So what exactly does it break an URL up into then?

Well, given an URL like below, parse_url would return the following:

$url = ‘http://username:password@hostname/path?arg=value#anchor’;

print_r(parse_url($url));

echo parse_url($url, PHP_URL_PATH);

The output:

Array
(
[scheme] => http
[host] => hostname
[user] => username
[pass] => password
[path] => /path
[query] => arg=value
[fragment] => anchor
)

/path

So pretty useful if you want say just the host or query value from a given URL then!

Another thing to note is that it is not designed to work with relative URLs, meaning that you do need to provide it with fully qualified URLs in order to get something usable back.

Still, a pretty nifty little function to keep in mind when writing parsing scripts…

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

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• centos 6 2 ipv6 (1)
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Thus I was curious if Debian guys were smart enough to implement a proxy cache cleaning option as an option to be passed on to squid’s init script.

Honestly I was quite suprised squid clear cache option is not there;

squid-cache:~# /etc/init.d/squid3
Usage: /etc/init.d/squid3 {start|stop|reload|force-reload|restart}
squid-cache:/#


As it was not embedded into init script I still hoped, there might be some Debian way to do the proxy cache clearing, so I spend some 10 minutes checking online as well as checked in squid3‘s manual just to find there is no specific command or Debian accepted way to clean squid’s cache.

Since I couldn’t find any Debian specific, way I did it the old fashioned way (deleted directory/file structures in /var/spool/squid3/* and used squid’s -z option, to recreate the swap directories.

Here is how:

squid-cache:~# /etc/init.d/squid3 stop;
squid-cache:~# rm -Rf /var/spool/squid3/*;
squid-cache:~# squid3 -z; /etc/init.d/squid3 start


Finally I was quite amazed to realize, there was not even a crontab script to periodically clear and re-create proxy cache.

My previous experience with maintaning an office Squid proxy cache has prooved, that periodic cache clean ups are very helpful, especially to resolve issues with cached unreslovable DNS entries in the server.
Clearing up squid cache every week or something, guarantees that failure to resolve certain hosts at certain times would not stay unresolvable like forever

In that manner of thougths, I decided to put the following crontab which will twice a month clear up proxy’s cache, to possibly solve some failed squid DNS issues.

squid-cache:~# crontab -u root -l > file;
echo '00 04 12,26 * * /etc/init.d/squid3 stop; rm -Rf /var/spool/squid3/*; squid3 -z; /etc/init.d/squid3 start >/dev/null 2>&1'
>> file; crontab file


By the way, implementing the squid clear cache in Debian and Ubuntu ‘s init scripts and putting a periodic proxy clear up cron, seems like a feature worthy to be proposed to the distro developers and hopefully be embbed in some of the upcoming distro releases

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#!/bin/sh
user="$1";
realm="$2";
pass="$3";
if [ -z "$1" -o -z "$2" -o -z "$3" ] ; then
echo "Usage: $0 user password 'realm'";
exit 1
fi
ha1=$(echo -n "$user:$realm:$pass"|md5sum |cut -f1 -d' ')
echo "$user:$realm:$ha1"

You can alternatively download the squid_generate_pass.sh script here

The script accepts three arguments;

proxy-server:~# ./squid_generate_pass.sh
Usage: ./squid_generate_pass.sh user password 'realm'

Thus to generate a new user and password and insert it immediately into let’s say a squid configured user/pass file in /etc/squid3/users execute command:

proxy-server:~# ./squid_generate_pass.sh admin_user MySecretPassword 'Squid_Configured_Realm'
>> /etc/squid3/users

Where Squid_Configured_Realm depends on the realm name configured in squid.conf, for example if squid.conf includes some auth configuration similar to:

auth_param digest program /usr/lib/squid3/digest_pw_auth -c /etc/squid3/users
auth_param digest children 2
auth_param digest realm My_Proxy_Realm
acl localusers proxy_auth REQUIRED

The realm script argument should be My_Proxy_realm . If squid_generate_pass does completes without errors, it should add a line to /etc/squid3/users file similar to:

proxy-server:~# cat /etc/squid3/users
admin_user:My_Proxy_realm:3bbcb35e505c52a0024ef2e3ab1910b0

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If not, please follow this article to install squid proxy server on CentOS 6.2/RHEL 6 (How to Install and Configure Squid Proxy Server on CentOS 6.2/RHEL 6)

1. Open the squid.conf configuration file :

[root@php2s ~]# vi /etc/squid/squid.conf

2. In this example, the setup just allow surfing_hour’s access from the php2s.com network, while always restricting access to ehowstuff.com network other than surfing hour.

# Example rule allowing access from your local networks.
# Adapt to list your (internal) IP networks from where browsing
# should be allowed
acl php2s.com src 192.168.1.0/24    # Your php2s.com internal network

3. Define surfing_hour group’s name and time.

#Add this at the bottom of the ACL Section
#
acl surfing_hours time M T W H F 08:00-17:00
#

4. Always restricting access to php2s.com, but allow during surfing hours only.

# Only allow cachemgr access from php2s.com
http_access allow php2s.com surfing_hours
http_access deny php2s.com

5. Restart Squid proxy server to take effect :

[root@php2s ~]# service squid restart
Stopping squid: ................                           [  OK  ]
Starting squid: .                                          [  OK  ]

Full Configuration of the Squid Cache Proxy Configuration :

#
# Recommended minimum configuration:
#
acl manager proto cache_object
acl localhost src 127.0.0.1/32 ::1
acl to_localhost dst 127.0.0.0/8 0.0.0.0/32 ::1

# Example rule allowing access from your local networks.
# Adapt to list your (internal) IP networks from where browsing
# should be allowed
acl localnet src 10.0.0.0/8	# RFC1918 possible internal network
acl localnet src 172.16.0.0/12	# RFC1918 possible internal network
acl localnet src 192.168.0.0/16	# RFC1918 possible internal network
acl localnet src fc00::/7       # RFC 4193 local private network range
acl localnet src fe80::/10      # RFC 4291 link-local (directly plugged) machines
acl php2s.com src 192.168.1.0/24    # Your php2s.com internal network

acl SSL_ports port 443
acl Safe_ports port 80		# http
acl Safe_ports port 21		# ftp
acl Safe_ports port 443		# https
acl Safe_ports port 70		# gopher
acl Safe_ports port 210		# wais
acl Safe_ports port 1025-65535	# unregistered ports
acl Safe_ports port 280		# http-mgmt
acl Safe_ports port 488		# gss-http
acl Safe_ports port 591		# filemaker
acl Safe_ports port 777		# multiling http
acl CONNECT method CONNECT

#Add this at the bottom of the ACL Section
#
acl surfing_hours time M T W H F 08:00-17:00
#
# Recommended minimum Access Permission configuration:
#
# Only allow cachemgr access from localhost
http_access allow manager localhost
http_access deny manager

# Only allow cachemgr access from ehowstuff.com
http_access allow php2s.com surfing_hours
http_access deny php2s.com

# Deny requests to certain unsafe ports
http_access deny !Safe_ports

# Deny CONNECT to other than secure SSL ports
http_access deny CONNECT !SSL_ports

# We strongly recommend the following be uncommented to protect innocent
# web applications running on the proxy server who think the only
# one who can access services on "localhost" is a local user
#http_access deny to_localhost

#
# INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS
#

# Example rule allowing access from your local networks.
# Adapt localnet in the ACL section to list your (internal) IP networks
# from where browsing should be allowed
#http_access allow localnet
http_access allow localhost
http_access allow php2s.com

# And finally deny all other access to this proxy
http_access deny all

# Squid normally listens to port 3128
http_port 3128

# We recommend you to use at least the following line.
hierarchy_stoplist cgi-bin ?

# Uncomment and adjust the following to add a disk cache directory.
#cache_dir ufs /var/spool/squid 100 16 256

# Leave coredumps in the first cache dir
coredump_dir /var/spool/squid

# Add any of your own refresh_pattern entries above these.
refresh_pattern ^ftp:		1440	20%	10080
refresh_pattern ^gopher:	1440	0%	1440
refresh_pattern -i (/cgi-bin/|\?) 0	0%	0
refresh_pattern .		0	20%	4320

if you like the tutorial please subscribe.

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Also download via torrent will prevent corrupt HTTP downloads, Ubuntu torrent links below:

Ubuntu 11.10 torrents

Ubuntu 11.10 Alternate Torrent

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Ubuntu 11.10 Desktop Torrent

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Ubuntu 110.10 Server Torrent

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Ubuntu 10.04 LTS Torrents

Ubuntu 10.04 LTS Alternate Torrent

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Ubuntu 10.04 LTS Netbook Torrent

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Ubuntu 10.04 LTS Server Torrent

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These Ubuntu Torrent links should be the fastest around, have fun installing and using your new Ubuntu systems.

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Squid service plays two main roles which mainly act as a caching proxy server between the user and the web. Second role, squid also regularly used as a content accelerator, or reverse proxy, intercepting requests to a server and using a cached version of the page to serve the request. Follow below steps to install and configure squid.

1. Install Squid proxy using yum command. This installation is performed using local yum repository as documented in this article.

[root@php2s ~]# yum install squid -y

2. Configure server hosts file :

[root@php2s ~]# vi /etc/hosts

127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6

192.168.1.44 linux.php2s.com

3. Configure main squid configuration file. Use vi to edit.

[root@php2s ~]# vi /etc/squid/squid.conf

4. Add your internal network name into the IP networks list where browsing should be allowed. In this example, your internal network name is php2s.com.

acl localnet src 10.0.0.0/8     # RFC1918 possible internal network
acl localnet src 172.16.0.0/12  # RFC1918 possible internal network
acl localnet src 192.168.0.0/16 # RFC1918 possible internal network
acl localnet src fc00::/7       # RFC 4193 local private network range
acl localnet src fe80::/10      # RFC 4291 link-local (directly plugged) machines
acl ehowstuff.com src 192.168.1.0/24    # Your internal network

5. Add php2s.com network in the ACL section list IP networks where browsing should be allowed :

#http_access allow localnet
http_access allow localhost
http_access allow php2s.com

6. Make sure squid proxy port is uncomment. You can change the proxy port to any available port here. As an example, other available port is 8080.

# Squid normally listens to port 3128
http_port 3128

7. Configure auto start at boot for squid service :

[root@php2s ~]# chkconfig squid on

8. Start squid service :

[root@php2s ~]# service squid restart
Stopping squid: …………….                           [  OK  ]
Starting squid: .                                          [  OK  ]

9. Client browser configuration should be as below :

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What`s new on Openshot 1.4.1:

• New 3D animation (wireframe text)
• New Titles (gold)
• New Effects (fish eye)
• New Animation Presets
• Support for Blender 2.6.X
• Localization fixes (seg faults, audio volume, rotation effect)
• UI bugs (disappearing icons using some GTK themes)
• Improved Help Manual
• Improved Title UI (interactive font list)
• Improved Precision (clip length, default image length)
• Tons of bug fixes! (view all bug reports)

Installation of Openshot1.4.1

- Ubuntu and LinuxMint  ppa:

Open terminal and enter the following commands:

sudo add-apt-repository ppa:jonoomph/openshot-edge
sudo apt-get update
sudo apt-get install openshot openshot-doc

- For other Linux distribution, please download this new release from the download page

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Nginx is known for its high performance, stability, rich feature set, simple configuration, and low resource consumption. This tutorial will help those who is trying to install Nginx with HTTPS support.

Note: The ssl certification is self generated. Therefore it is not recommended for commercial websites, though it can be used for personal use such as hosting an administration area

Download Nginx and Install It

cd
wget http://nginx.org/download/nginx-1.0.11.tar.gz
tar -zxvf nginx-1.0.11.tar.gz
cd nginx-1.0.11
./configure  –with-http_ssl_module
make
make install

Now, let us generate a self signed ssl certificate valid for 1 year

cd /usr/local/nginx/conf
openssl genrsa -out server.key 1024
openssl req -new -key server.key -out server.csr -subj “/C=ab/ST=cd/L=ef/CN=ghij”
mv server.key server.key.org
openssl rsa -in server.key.org -out server.key
openssl x509 -req -days 365 -in server.csr -signkey server.key -out server.crt

Final step
Edit nginx configuration

nano /usr/local/nginx/conf/nginx.conf

Comment out the https section

server {
listen       443;
server_name  localhost;

ssl                  on;
ssl_certificate      server.crt;
ssl_certificate_key  server.key;

ssl_session_timeout  5m;

ssl_protocols  SSLv2 SSLv3 TLSv1;
ssl_ciphers  HIGH:!aNULL:!MD5;
ssl_prefer_server_ciphers   on;

location / {
root   html;
index  index.html index.htm index.php;
}
}

That is fine.

Now you have to restart nginx to take effect

cd /usr/local/nginx/sbin/
./nginx -s stop
./nginx

Now you can browser https://serverip

Please subscribe us if you like this blog.

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GNU/Linux and FreeBSD are equipped with the split command. The purpose of this command is exactly the cutting of a file to a number of pieces.

On Linux the split command comes by default install to the system with the coreutils package on most Debian (deb) based and Redhat based (rpm) distributions, theerefore Linux’s version of split is GNU/split since it’s part of the GNU Coreutils package. An interesting fact about Linux split is that one of the two programmers who has coded it is Richard Stallman

On BSD Unix split is the AT&∓T UNIX (BSD) split

In the past splitting files in pieces was much more needed than today, as people used floppy drives to transfer data, though today with the bloom of Internet and the improve of the data carriers transferring even an extra large files from one place to another is a way more trivial task still at many occasions splitting it in pieces is needed.

Even though today splitting file is very rarely required, still there are times when being able to split a file in X number of parts is very much needed.
Maybe the most common use of splitting a file today is necessery when a large SQL file dumps, like let’s say 200 MBytes of info database needs to be moved from ane hosting provider to another one.
Many hosting providers does disallow direct access with standard mySQL client programs to the database directly and only allow a user to connect only via phpMyAdmin or some other web interface like Cpanel to improve data into the SQL or PostgreSQL server.

In such times, having knowledge on the Unix split command is a priceless asset.

Even though on Linux and BSD the code for the split command is not identical and GNU/split and BSD/split has some basic differences, the use of split on both of these Unices is identical.
The way to split a file in few pieces using on both Linux and BSD OSes is being done with one and the same command, here is how:

1. Splitting file in size of 40 mb On Linux

linux:~# split -b 40m SQL-Backup-Data.sql SQL-Backup-Data_split


2. Splitting file in size of 40mb on BSD (FreeBSD, OpenBSD, NetBSD)

freebsd# split -b 40m SQL-Backup-Data.sql SQL-Backup-Data_split


The Second argument the split command takes is actually called a prefix, the prefix is used as a basis name for the creation of the newly generated files cut in pieces file based on SQL-Backup-Data.sql.

As I said identical command will split the SQL-Backup-Data.sql files in a couple of parts which of it will be sized 40 megas.

These command will generate few files output like:

freebsd# ls -1 SQL-Backup-Dat*SQL-Backup-Data.sql
SQL-Backup-Dataa
SQL-Backup-Dataab
SQL-Backup-Dataac
SQL-Backup-Dataad
SQL-Backup-Dataae


As you see the SQL-Backup-Data.sql with size 200MB is being split in four files each of which is sized 40mbytes.

After the files are transfered to another Linux or BSD host, they can easily be again united in the original file with the command:

linux:~# for i in $(ls -1 SQL-Backup-Data_split*); echo $i >> SQL-Backup-Data.sql


Alternatively in most Unices also using cat should be enough to collect back the pieces into the original file, like so:

freebsd# cat SQL-Backup-Data_split* >> SQL-Backup-Data.sql

Hope the tutorial will be useful.

∓

AT

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Before to start installing the Forum, you need to  Install LAMP on Debian, to complete this step.

Here are the exact steps I followed to have a properly it properly instlled:

1. Install the phpbb3 debian package
This was pretty straight forward:

debian:~# apt-get install phpbb3


At this point of installation I’ve faced a dpkg-reconfigure phpbb deb package configuration issue:
I was prompted to pass in the credentials for my MySQL password right after I’ve selected the MySQL as my preferred database back engine.
I’ve feeded my MySQL root password as well as my preferred forum database name, however the database installation failed because, somehow the configuration procedure tried to connect to my MySQL database with the htcheck user.
I guess this has to be a bug in the package itself or something from my previous installation misconfigured the way the debian database backend configuration was operating.
My assumption is that my previously installed htcheck package or something beforehand I’ve done right after the htcheck and htcheck-php packages installation.

after the package configuration failed still the package had a status of properly installed when I reviewed it with dpkg
I’ve thought about trying to manually reconfigure it using the dpkg-reconfigure debian command and I gave it a try like that:

debian:~# dpkg-reconfigure phpbb3


This time along with the other fields I’ve to fill in the ncurses interface I was prompted for a username before the password prompted appeared.
Logically I tried to fill in the root as it’s my global privileges MySQL allowed user.
However that didn’t helped at all and again the configuration tried to send the credentials with user htcheck to my MySQL database server.
To deal with the situation I had to approach it in the good old manual way.

2. Manually prepare / create the required phpbb forum database

To completet that connected to the MySQL server with the mysql client and created the proper database like so:

debian:~# mysql -u root -p
mysql>
CREATE database phpbb3forum;


3. Use phpmyadmin or the mysql client command line to create a new user for the phpbb forum

Here since adding up the user using the phpmyadmin was a way easier to do I decided to go that route, anyways using the mysql cli is also an option.

From phpmyadmin It’s pretty easy to add a new user and grant privileges to a certain database, to do so navigate to the following database:

Privileges -> -> Add a new user ->

Now type your User name: , Host , Password , Re-type password , also for a Host: you have to choose Local from the drop down menu.

Leave the Database for user field empty as we have already previously created our desired database in step 2 of this article

Now press the “Go” button and the user will get created.

Further after choose the Privileges menu right on the bottom of the page once again, select through the checkbox the username you have just created let’s say the previously created user is phpbb3

Go to Action (There is a picture with a man and a pencil on the right side of this button

Scroll down to the page part saying Database-specific privileges and in the field Add privileges on the following database: fill in your previosly created database name in our case it’s phpbb3forum

and then press the “Go” button once again.
A page will appear where you will have to select the exact privileges you would like to grant on the specific selected database.
For some simplicity just check all the checkbox to grant as many privilegs to your database as you could.
Then again you will have to press the “Go” button and there you go you should have already configured an username and database ready to go with your new phpbb forum.

4. Create a virtualhost if you would like to have the forum as a subdomain or into a separate domain

If you decide to have the forum on a separate sub-domain or domain as I did you will have to add some kind of Virtualhost into either your Apache configuration /etc/apache2/apache2.conf or into where officially the virutualhosts are laid in Debian Linux in /etc/apache2/sites-available
I’ve personally created a new file like for instance /etc/apache2/sites-available/mysubdomain.mydomain.com

Here is an example content of the new Virtualhost:

<VirtualHost *>
ServerAdmin admin-email@domain.com
ServerName mysubdomain.domain.com

# Indexes + Directory Root.
DirectoryIndex index.php index.php5 index.htm index.html index.pl index.cgi index.phtml index.jsp index.py index.asp

DocumentRoot /usr/share/phpbb3/www/

# Logfiles
ErrorLog /var/log/apache2/yourdomain/error.log
CustomLog /var/log/apache2/yourdomain/access.log combined
# CustomLog /dev/null combined
<Directory /usr/share/phpbb3/www/>
Options FollowSymLinks MultiViews -Includes ExecCGI
AllowOverride All
Order allow,deny
allow from all </Directory>
</VirtualHost>


In above Virtualhost just change the values for ServerAdmin , ServerName , DocumentRoot , ErrorLog , CustomLog and Directory declaration to adjust it to your situation.

5. Restart the Apache webserver for the new Virtualhost to take affect

debian:~# /etc/init.d/apache2 restart


Now accessing your http://mysubdomain.domain.com should display the installed phpbb3 forum
The default username and password for your forum you can use straight are:

username: admin
password: admin

So far so good you by now have the PHPBB3 forum properly installed and running, however if you try to Register a new user in the forum you will notice that it’s impossible because of a terrible ugly message reading:

Sorry but this board is currently unavailable.

I’ve spend few minutes online to scrape through the forums before I can understand what I have to stop that annoying message from appearing and allow new users to register in the phpbb forum

The solution came natural and was a setting that had to be changed with the forum admin account, thus login as admin and look at the bottom of the page, below the text reading Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group you will notice a link with Administration Control Panel
just press there a whole bunch of menus will appear on the screen allowing you to do numerous things, however what you will have to do is go to Board Settings -> Disable Board and change the radio button there to say No

That’s all now your forum will be ready to go and your users can freely register and if the server where the forum is installed has an already running mail server, they will receive an emails with a registration data concerning their new registrations in your new phpbb forum.
Cheers and Enjoy your new shiny phpbb Forum

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Common monit usage:

• Monit can start a process if it does not run.
• Restart a process if it does not respond.
• Stop a process if it uses to much resources etc.

Installation on CentOS

yum install openssl*
wget http://mmonit.com/monit/dist/monit-5.3.2.tar.gz
tar -zxf monit-5.3.2.tar.gz
cd monit-5.3.2
./configure
make && make install
cp monitrc /etc/
cd ..
rm -rf monit-5.3.2*
echo “include /etc/monit.d/*” >> /etc/monitrc
chmod 700 /etc/monitrc
mkdir /etc/monit.d/
nano /etc/monit.d/apache

And copy/paste the following and save the file

Note: If you are on cPanel, use the codeblock posted next to the below post

check process httpd with pidfile /var/run/httpd.pid
group apache
start program = “/etc/init.d/httpd start”
stop program = “/etc/init.d/httpd stop”
if failed host 127.0.0.1 port 80 protocol http
and request “/test.html”
then restart
if 5 restarts within 5 cycles then timeout

check process httpd with pidfile /usr/local/apache/logs/httpd.pid
group nobody
start program = “/scripts/restartsrv httpd”
stop program = “/scripts/restartsrv httpd”
if failed host 127.0.0.1 port 80 protocol http
and request “/test.html”
then restart
if 5 restarts within 5 cycles then timeout

I believe, it is better if you use “/scripts/restartsrv httpd” instead of “/etc/init.d/httpd start” if you are on cPanel/WHM server.

Note: Next step may change according to your system configuration. The location of apache on cPanel server is
 /usr/local/apache and htdocs will be /usr/local/apache/htdocs

So you should use this command provided below

echo “Test file” > /usr/local/apache/htdocs/test.html

If you are not using cPanel, then the apache location may be /etc/httpd and htdocs may be /var/www/html. In that case, change the code accordingly

echo “Test file” > /var/www/html/test.html

Add monit to rc.local so that it starts automatically when your server starts.

echo “/usr/local/bin/monit -d 60 -v -c /etc/monitrc  -p /var/run/monit.pid -l /var/log/monit.log” >> /etc/rc.local

Finally, execute monit now.

/usr/local/bin/monit -d 60 -v -c /etc/monitrc  -p /var/run/monit.pid -l /var/log/monit.log

You will see a message “Starting monit daemon” at the end if everything goes perfect.

That should start monit as deamon and check the ports on every 60 seconds.

Extending monit

You can monitor other services using monit such as mysql, exim etc. To do so, create a new file at /etc/monit.d/ and save it with the appropriate commands to check and restart code.

For example, if you want to monitor mysql, you can use the below commands

touch /etc/monit.d/mysql
echo “check process mysqld with pidfile /var/lib/mysql/`hostname`.pid” > /etc/monit.d/mysql
echo “start program = \”/etc/init.d/mysql start\”" >> /etc/monit.d/mysql
echo “stop program = \”/etc/init.d/mysql stop\”" >> /etc/monit.d/mysql
echo “if failed host 127.0.0.1 port 3306 then restart” >> /etc/monit.d/mysql
echo “if 5 restarts within 5 cycles then timeout” >> /etc/monit.d/mysql

Those commands will add the following lines to /etc/monit.d/mysql

check process mysqld with pidfile /var/lib/mysql/server.php2s.com.pid
start program = “/etc/init.d/mysql start”
stop program = “/etc/init.d/mysql stop”
if failed host 127.0.0.1 port 3306 then restart
if 5 restarts within 5 cycles then timeout

Be sure to re-execute monit after adding this.

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The installation of Lamp server  in  Debian Sqeeze  will be done in 3 steps :

1. Install apache2 + php5

Apache is one of the most famous web server which runs on most linux based servers. With just few commands you can configure apache to run with  PHP 5.

root@unixmen-debian6:~# apt-get install apache2 php5 libapache2-mod-php5

your  normal web folder is located in /var/www/

Now  lets  check if php is corectly  installed

vi /var/www/test.php

and  add

{codecitation}<?php phpinfo(); ?>{/codecitation}
save and exit

Now open browser with http://ip/test.php

2. Installing MySQL Database Server

To install MySQL, as root enter the following command:

apt-get install mysql-server mysql-client php5-mysql

in this  installation you will  get a  windows  to  insert  your root mysql password

- Or  yon can add it manually later  with :

mysql -u root mysql> USE mysql;mysql> UPDATE user SET Password=PASSWORD('your-password') WHERE user='root';mysql> FLUSH PRIVILEGES;

3. Install  PhpMyAdmin

Phpmyadmin is   easy webtool  to  manage  you  databases to install  it :

apt-get  install  phpmyadmin

Choose the  webserver that  you want  to use  , in my  case is apache2

Now open your browser with http://ip/phpmyadmin

Hope the tutorial will be useful.

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First, though, what are permissions?

Basically, every file and folder on a Ubuntu system can be accessed by three different groups of users – the owning user, the owning group, and everybody else with an account on the system. In Linux file permissions, “ownership” means that the owner, whether the owning user or the owning group, has full control over the file or folder. The owning user and group, obviously, are the particular user and group that have been assigned ownership of that file or folder. (The owner and the root user are the only ones who can change or assign permissions to a file.) Everyone else means every other user on the system.

There are three permissions that can be assigned to the owner, the owning group, and everyone else – read, write, and execute.

The Read permission allows you to access the file, but not to delete it or alter it. For example, you could open a document with the Read permission, but you could not edit it, and you could not delete it.

The Write permission allows you alter or delete a file. To return to our example document, if you have the Write permission, you could delete it or make changes to it. (Ironically, to actually view the document, you also need the Write permission.)

The Execute permission allows you to run a file as a program. Any application or program files need to have this permission, otherwise they won’t work.

So, how to change a file’s permissions? This is done using the chmod command. (In Linux, a file’s total permissions are called the “mode”, so chmod stands for “change mode.”) If you want to add the execute permission to the owning user of a file, you would use chmod like this (note that in chmod, u stands for the owning user):

chmod u+x test.txt

If you wanted to add the execute permission to the owning group:

chmod g+x test.txt

Finally, if you wanted to add the execute permission for everyone on the system:

chmod o+x test.txt

(In chmod, o stands for Others, or everyone else on the system.)

And to do all three at once:

chmod u+x,g+x,o+x test.txt

Alternately, to remove permissions, replace the + sign with the – symbol:

chmod u-x,g-x,o-x test.txt

All this typing is rather cumbersome, isn’t it? Fortunately, file permissions in Ubuntu Linux have numeric codes – mathematical shorthand, if you will. The Read permission is assigned the number 4, Write the number 2, and Execute the number 1. Having no permissions is represented by a zero. You then calculate the permissions by adding up the numbers. Take this example:

-rwxrw-r– 6 bobsmith users 4096 Dec 9 14:56 test.txt

The file’s owner receives the Read, Write, and Execute permissions, the owning group gets Read and Write, and everyone else gets Read. Since Read is 4, Write is 2, and Execute is 1, the file owner gets a permission of 7. The owning group gets a total of 6, and everyone else gets 4. The permissions can then be expression numerically as this:

764

And so to set the permissions as 764, you would use the chmod command:

chmod 764 test.txt

Much easier to simply type 764, isn’t it?

Or to give the owning user full permissions, while denying permissions to both the owning group and everyone else, use this command:

chmod 700 test.txt

Needless to say, this makes using the chmod command far less cumbersome. As another example, let us say you wanted to change the permissions of test.txt so that the owner can read, write and execute, the owning group can read and execute, and everyone on the system who is neither the owner nor the owning user can read the file but not write or execute. You would use this chmod command:

chmod 754 test.txt

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What is file and folder ownership? In Linux file permissions, “ownership” means that the owner, whether the owning user or the owning group, has full control over the file or folder. Basically, every file and folder on a Linux system can be accessed by three different groups of users – the owning user, the owning group, and everybody else with an account on the system. The owning user and group, obviously, are the particular user and group that have been assigned ownership of that file or folder. (The owner and the root user are the only ones who can change or assign permissions to a file.) Everyone else means every other user on the system.

Permissions are then assigned based on those groups – the owning user, the owning group, and all other users on the system.

Assigning permissions is useful, but it’s only the first half of managing security for your files and folders. You may also need to sometimes take ownership of files, or to assign them to different owners. Or you may need to assign a file to a different group.

To change the ownership of files, you can use the chown command. To assign the ownership of the test.txt file to a user named tim:

sudo chown tim test.txt

(You won’t need root permissions to change the ownership of files you already own, but you’ll need it while changing the ownership of files that you don’t own.)

You might have noticed that all this command only affects one file or directory at one time. How do you change the ownership of a large number of files at once? Like the cp or the mv commands, all the commands for managing permissions and ownership work with both the recursive -r option and with wildcards. For instance, to assign ownership of the /test directory, and all its files and sub-directories, to a user named tim:

sudo chown -r tim /test

Using chown, you can quickly manage both ownership on your Linux system.

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