Posts Tagged ‘run’

How to update macos from terminal / Check and update remotely Mac OS X software from console

Friday, October 23rd, 2015

../files/how-to-update-mac-osx-notebook-from-terminalsoftware-update-command-line-mac-screnshot-1

If you happen to have to deal with Mac OS X (Apple) notebook or Desktop PC (Hackintosh) etc. and you’re sysadmin or console freak being pissed off Mac’s GUI App Store update interface and you want to “keep it simple stupid” (KISS) in an Debian Linux like apt-get manner then you can also use Mac’s console application (cli) terminal to do the updates manually from command line with:

softwareupdate

command.

how-to-update-mac-osx-notebook-from-terminalsoftware-update-command-line-mac-screnshot

To get help about softwareupdate pass it on the -h flag:

softwareupdate -h

1. Get a list of available Mac OS updates

Though not a very likely scenario of course before installing it is always a wise thing to see what is being updated to make sure you will not upgrade something that you don’t want to.
This is done with:

softwareupdate -l

However in most cases you can simply skip this step as updating directly every package installed on the Mac with a new version from Apple will not affect your PC.
Anyways it is always a good idea to keep a backup image of your OS before proceeding with updates with let’s say Time Machine Mac OS backup app.

2. Install only recommended Updates from Apple store

softwareupdate -irv


Above will download all updates that are critical and thus a must to have in order to keep Mac OS security adequate.
Translated into Debian / Ubuntu Linux language, the command does pretty much the same as Linux’s:

apt-get –yes update

3. Install All Updates available from AppleStore

To install absolutely all updates provided by Apple’s package repositories run:

softwareupdate -iva

One note to make here is that always when you keep updating make sure your notebook is switched on to electricity grid otherwise if due to battery discharge it shutoffs during update your Mac will crash in a very crappy hard to recover state that might even cost you a complete re-install or a need to bring a PC to a Mac Store technical support guy so beware, you’re warned!

4. Installing all updates except Specific Softwares from Terminal

Often if you have a cracked software or a software whose GUI interface changed too much and you don’t want to upgrade it but an update is offered by Apple repos you can add the -i ingnore option:

softwareupdate -i [update_name(s)]

For example:

softwareupdate -i Safari-version-XXXX

5. View Mac OS Software Update History

The quickest way to see the update history is with System Information app, e.g.:

/Applications/Utilities/System Information.app

Check your Server Download / Upload Internet Speed from Console on Linux / BSD / Unix howto

Tuesday, March 17th, 2015

tux-check-internet-network-download-upload-speed-on-linux-console-terminal-linux-bsd-unix
If you've been given a new dedicated server from a New Dedicated-Server-Provider or VPS with Linux and you were told that a certain download speed to the Server is guaranteed from the server provider, in order to be sure the server's connection to the Internet told by service provider is correct it is useful to run a simple measurement console test after logging in remotely to the server via SSH.

Testing connection from Terminal is useful because as you probably know most of Linux / UNIX servers doesn't have a GUI interface and thus it is not possible to test Internet Up / Down Bandwidth through speedtest.net.
 

1. Testing Download Internet Speed given by ISP / Dedi-Server Provider from Linux Console

For the download speed (internet) test the historical approach was to just try downloading the Linux kernel source code from www.kernel.org with some text browser such as lynx or links count the seconds for which the download is completed and then multiple the kernel source archive size on the seconds to get an approximate bandwidth per second, however as nowdays internet connection speeds are much higher, thus it is better to try to download some Linux distribution iso file, you can still use kernel tar archive but it completed too fast to give you some good (adequate) statistics on Download bandwidth.

If its a fresh installed Linux server probably you will probably not have links / elinks and lynx text internet browers  installed so install them depending on deb / rpm distro with:

If on Deb Linuz distro:

 

root@pcfreak:/root# apt-get install –yes links elinks lynx

 

On RPM Based Linuz distro:
 

 

[root@fedora ~]# yum install -y lynx elinks links

 

Conduct Internet  Download Speed with links
root@pcfreak:/root# links https://www.kernel.org/pub/linux/kernel/v3.x/linux-3.19.1.tar.xz

check_your_download_speed-from-console-linux-with-links-text-browser

(Note that the kernel link is current latest stable Kernel source code archive in future that might change, so try with latest archive.)

You can also use non-interactive tool such as wget curl or lftp to measure internet download speed

To test Download Internet Speed with wget without saving anything to disk set output to go to /dev/null 

 

root@pcfreak:~# wget -O /dev/null https://www.pc-freak.net//~hipo/hirens-bootcd/HirensBootCD15/Hirens.BootCD.15.0.zip

 

check_bandwidth_download-internet-speed-with-wget-from-console-non-interactively-on-linux

You see the Download speed is 104 Mbit/s this is so because I'm conducting the download from my local 100Mbit network.

For the test you can use my mirrored version of Hirens BootCD

2. Testing Uplink Internet speed provided by ISP / Server Provider from Linux (SSH) Console

To test your uplink speed you will need lftp or iperf command tool.

 

root@pcfreak:~# apt-cache show lftp|grep -i descr -A 12
Description: Sophisticated command-line FTP/HTTP client programs
 Lftp is a file retrieving tool that supports FTP, HTTP, FISH, SFTP, HTTPS
 and FTPS protocols under both IPv4 and IPv6. Lftp has an amazing set of
 features, while preserving its interface as simple and easy as possible.
 .
 The main two advantages over other ftp clients are reliability and ability
 to perform tasks in background. It will reconnect and reget the file being
 transferred if the connection broke. You can start a transfer in background
 and continue browsing on the ftp site. It does this all in one process. When
 you have started background jobs and feel you are done, you can just exit
 lftp and it automatically moves to nohup mode and completes the transfers.
 It has also such nice features as reput and mirror. It can also download a
 file as soon as possible by using several connections at the same time.

 

root@pcfreak:/root# apt-cache show iperf|grep -i desc -A 2
Description: Internet Protocol bandwidth measuring tool
 Iperf is a modern alternative for measuring TCP and UDP bandwidth performance,
 allowing the tuning of various parameters and characteristics.

 

To test Upload Speed to Internet connect remotely and upload any FTP file:

 

root@pcfreak:/root# lftp -u hipo www.pc-freak.net -e 'put Hirens.BootCD.15.0.zip; bye'

 

uploading-file-with-lftp-screenshot-test-upload-internet-speed-linux

On Debian Linux to install iperf:

 

root@pcfreak:/root# apt-get install –yes iperf

 

On latest CentOS 7 and Fedora (and other RPM based) Linux, you will need to add RPMForge repository and install with yum

 

[root@centos ~]# rpm -ivh  rpmforge-release-0.5.3-1.el7.rf.x86_64.rpm

[root@centos ~]# yum -y install iperf

 

Once having iperf on the server the easiest way currently to test it is to use
serverius.net speedtest server –  located at the Serverius datacenters, AS50673 and is running on a 10GE connection with 5GB cap.

 

root@pcfreak:/root# iperf -c speedtest.serverius.net -P 10
————————————————————
Client connecting to speedtest.serverius.net, TCP port 5001
TCP window size: 16.0 KByte (default)
————————————————————
[ 12] local 83.228.93.76 port 54258 connected with 178.21.16.76 port 5001
[  7] local 83.228.93.76 port 54252 connected with 178.21.16.76 port 5001
[  5] local 83.228.93.76 port 54253 connected with 178.21.16.76 port 5001
[  9] local 83.228.93.76 port 54251 connected with 178.21.16.76 port 5001
[  3] local 83.228.93.76 port 54249 connected with 178.21.16.76 port 5001
[  4] local 83.228.93.76 port 54250 connected with 178.21.16.76 port 5001
[ 10] local 83.228.93.76 port 54254 connected with 178.21.16.76 port 5001
[ 11] local 83.228.93.76 port 54255 connected with 178.21.16.76 port 5001
[  6] local 83.228.93.76 port 54256 connected with 178.21.16.76 port 5001
[  8] local 83.228.93.76 port 54257 connected with 178.21.16.76 port 5001
[ ID] Interval       Transfer     Bandwidth
[  9]  0.0-10.2 sec  4.05 MBytes  3.33 Mbits/sec
[ 10]  0.0-10.2 sec  3.39 MBytes  2.78 Mbits/sec
[ 11]  0.0-10.3 sec  3.75 MBytes  3.06 Mbits/sec
[  4]  0.0-10.3 sec  3.43 MBytes  2.78 Mbits/sec
[ 12]  0.0-10.3 sec  3.92 MBytes  3.18 Mbits/sec
[  3]  0.0-10.4 sec  4.45 MBytes  3.58 Mbits/sec
[  5]  0.0-10.5 sec  4.06 MBytes  3.24 Mbits/sec
[  6]  0.0-10.5 sec  4.30 MBytes  3.42 Mbits/sec
[  8]  0.0-10.8 sec  3.92 MBytes  3.03 Mbits/sec
[  7]  0.0-10.9 sec  4.03 MBytes  3.11 Mbits/sec
[SUM]  0.0-10.9 sec  39.3 MBytes  30.3 Mbits/sec

 

You see currently my home machine has an Uplink of 30.3 Mbit/s per second, that's pretty nice since I've ordered a 100Mbits from my ISP (Unguaranteed Bandwidth Connection Speed) and as you might know it is a standard practice for many Internet Proviers to give Uplink speed of 1/4 from the ISP provided overall bandwidth 1/4 would be 25Mbi/s, meaning my ISP (Bergon.NET) is doing pretty well providing me with even more than promised (ordered) bandwidth.

Iperf is probably the choice of most sysadmins who have to do regular bandwidth in local networks speed between 2 servers or test  Internet Bandwidth speed on heterogenous network with Linux / BSDs / AIX / HP-UX (UNIXes). On HP-UX and AIX and other UNIXes for which iperf doesn't have port you have to compile it yourself.

If you don't have root /admin permissions on server and there is python language enterpreter installed you can use speedtest_cli.py script to test internet throughput connectivity
speedtest_cli uses speedtest.net to test server up / down link just in case if script is lost in future I've made ownload mirror of speedtest_cli.py is here

Quickest way to test net speed with speedtest_cli.py:

 

$ lynx -dump https://raw.github.com/sivel/speedtest-cli/master/speedtest_cli.py > speedtest_cli.py
$ chmod +x speedtest_cli.py
python speedtest_cli.py

speedtest_cli_pyhon_script_screenshot-on-gnu-linux-test-internet-network-speed-on-unix

How to completely disable Replication in MySQL server 5.1.61 on Debian GNU / Linux

Monday, July 16th, 2012

Replication_mysql_disable

Some time ago on one of the Database MySQL servers, I've configured replication as it was required to test somethings. Eventually it turned out replication will be not used (for some reason) it was too slow and not fitting our company needs hence we needed to disable it.

It seemed logical to me that, simply removing any replication related directives from my.cnf and a restart of the SQL server will be enough to turn replication off on the Debian Linux host. Therefore I proceeded removed all replication configs from /etc/my/my.cnf and issued MySQL restart i. e.:

sql-server:~# /etc/init.d/mysql restart
....

This however didn't turned off replication,as I thought and in phpmyadminweb frontend interface, replication was still appearing to be active in the replication tab.

Something was still making the SQL server still act as an Replication Slave Host, so after a bit of pondering and trying to remember, the exact steps I took to make the replication work on the host I remembered that actually I issued:

mysql> START SLAVE;

Onwards I run:

mysql> SHOW SLAVE STATUS;
....

and found in the database the server was still running in Slave Replication mode

Hence to turn off the db host run as a Slave, I had to issue in mysql cli:

mysql> STOP SLAVE;
Query OK, 0 rows affected, 1 warning (0.01 sec)
mysql> RESET SLAVE;
Query OK, 0 rows affected, 1 warning (0.01 sec)

Then after a reload of SQL server in memory, the host finally stopped working as a Slave Replication host, e.g.

sql-server:~# /etc/init.d/mysql restart
....

After the restart, to re-assure myself the SQL server is no more set to run as MySQL replication Slave host:

mysql> SHOW SLAVE STATUS;
Empty set (0.00 sec)

Cheers 😉

WordPress Security: Fix WordPress wp-config.php improper permissions to protect your sites from Database password steal / Website deface

Thursday, March 12th, 2015

wordpress-security-Fix-wordpress-wp-config-improper-permissions-to-protect-your-sites-from-Database-pass-steal
Keeping WordPress Site / Blog and related installed plugins up-to-date
is essential to prevent an attacker to hack into your Site / Database and deface your site, however if you're a company providing shell access from Cpanel / Plesk / Kloxo Panel to customers often customers are messing up permissions leaving important security credential files such as wp-config.php (which is storing user / pass credentials about connection to MySQL / PostgreSQL to have improper permissions and be world readable e.g. have permissions such as 666 or 777 while in reality the WordPress recommended permissions for wp-config.php is 600. I will skip here to explain in details difference between file permissions on Linux as this is already well described in any Linux book, however I just will recommend for any Share hosting Admin where Wordperss is hosted on Lighttpd / Apache Webserver + Some kind of backend database to be extra cautious.

Hence it is very useful to list all your WordPress sites on server wp-config.php permissions with find like this:

 

find /  -iname 'wp-config.php' -print1;

 

I find it a generally good practice to also automatically set all wp-config.php permissions to 600 (6= Read / Write  permissions only for File Owner  user 0 = No permissions for All groups, 0 = No Permissions for all non-owner users)

If find command output gives you some file permissions such as:
 

ls -al /var/www/wordpress-bak/wp-config.php
-rw-rw-rw- 1 www-data www-data 2654 jul 28  2009 wp-config.php

 

E.g. file permission has 666 permissions (Readable for all users), then it is wise to fix this with:
 

chmod 600 /var/www/wordpress-bak/wp-config.php


It is generally a very good practice to run also a chmod 600 to each and every found wp-config.php file on server:
 

find /  -iname 'wp-config.php' -print1 -exec chmod 600 '{}' \;


Above command will also print each file to whcih permission is set to Read / Write for Owner (this si done with -print1 option).

It is a good practice for shared hosting server to always configure a root cronjob to run above find chmod command at least once daily (whenever server hosts 50 – 100 wordpress+ more sites).
 

crontab -u root -l | { cat; echo “05 03 * * * find /  -iname 'wp-config.php' -print1 -exec chmod 600 '{}' \; } | crontab – 


If you don't have the 600 permissions set for all wp-config.php files this security "backdoor" can be used by any existing non-root user to be read and to break up (crack)  in your database and even when there are Deface bot-nets involved to deface all your hosted server wordpress sites.

One of my servers with wordpress has just recently suffered with this little but very important security hole due to a WordPress site directory backup  with improper permissions which allowed anyone to enter MySQL database, so I guess there are plenty of servers with this hidden vulnerability silently living.

Many thanks to my dear friend (Dimitar PaskalevNomen for sharing with me about this vulnerability! Very important note to make here is admins who are using some security enhancement modules such as SuPHP (which makes Apache webserver to run Separate Website instances with different user), should be careful with his set all wp-config.php modules to Owner, as it is possible the wp-config.php owner change to make customer WP based websites inaccessible.

Another good security measure to  protect your server WordPress based sites from malicious theme template injections (for both personal own hosted wordpress based blog / sites or a WordPress hosting company) is to install and activate WordPress Antivirus plugin.

Speed up WordPress / Joomla CMS and MySQL server on Linux with tmpfs ram file system / Decrease Website pageload times with RAM caching

Wednesday, March 4th, 2015

speed-up-accelerate-wordpress-joomla-drupal-cms-and-mysql-server-with-tmpfs_ramfs_decrease-pageload-times-with-ram-caching
As a WordPress blog owner and an sys admin that has to deal with servers running a lot of WordPress / Joomla / Droopal and other custom CMS installed on servers, performoing slow or big enough to put a significant load on servers
and I love efficiency and hardware cost saving is essential for my daily job, I'm constantly trying to find new ways to optimize Customer Website (WordPress) and rest of sites in order to utilize better our servers and improve our clients sites speed (and hence satisfaction). 

There is plenty of little things to do on servers but probably among the most crucial ones which we use nowadays that save us a lot of money is tmpfs, and earlier (ramfs) – previously known as shmfs).
TMPFS is a (Temporary File Storage Facility) Linux kernel technology based on ramfs (used by Linux kernel initrd / initramfs on boot time in order to load and store the Linux kernel in memory, before system hard disk partition file systems are mounted) which is heavily used by virtually all modern popular Linux distributions. 

Using ramfs (cramfs variation – Compressed ROM filesystem) has been used to store different system environment kernel and Desktop components of many Linux environment / applications and used by a lot of the Linux BootCD such as the most famous (Klaus Knopper's) KNOPPIX LiveCD and Trinity Rescue Kit Linux (TRK uses /dev/shm which btw can be seen on most modern Linux distros and is actually just another mounted tmpfs).
If you haven't tried Live Linux yet try it out as me and a lot of sysadmins out there use some kind of LiveLinux at least few times on yearly basis  to Recover Unbootable Linux servers after some applied remote Updates as well as for Rescuing (Save) Data from Linux server failing to properly boot because of hard disk (bad blocks) failures. As I said earlier TMPFS is also used on almost any distribution for the /dev/ filesystem which is kept in memory.

You can see which tmpfs partitions is used on your Linux server with:

 

debian-server:~# mount |grep -i tmpfs
tmpfs on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
udev on /dev type tmpfs (rw,mode=0755)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)

 

Above is an output from a standard Debian Linux server. On CentOS 7 standard mounted tmpfs are as follows:

 

[root@centos ~]# mount |grep -i tmpfs
devtmpfs on /dev type devtmpfs (rw,nosuid,seclabel,size=1016332k,nr_inodes=254083,mode=755)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev,seclabel)
tmpfs on /run type tmpfs (rw,nosuid,nodev,seclabel,mode=755)
tmpfs on /sys/fs/cgroup type tmpfs (rw,nosuid,nodev,noexec,seclabel,mode=755)

 

[root@centos ~]# df -h|grep -i tmpfs
devtmpfs                 993M     0  993M   0% /dev
tmpfs                   1002M   92K 1002M   1% /dev/shm
tmpfs                   1002M  8.8M  993M   1% /run
tmpfs                   1002M     0 1002M   0% /sys/fs/cgroup

The /run tmpfs mounted directory is also to be seen also on latest Ubuntus and Fedoras and is actually the good old /var/run ( where applications keep there pids and some small app related files) stored in tmpfs filesystem stored in memory.

If you're wondering what is /dev/shm and why it appears mounted on every single Linux Server / Desktop you've ever used this is a special filesystem shared memory which various running programs (processes) can use to transfer data quick and efficient between each other to preven the slow disk swapping. People using Linux for the rest 15 years should remember /dev/shm has been a target of a lot of kernel exploits as historically it had a lot of security issues.

While writting this article I've just checked about KNOPPIX developed amd just for info as of time of writting this distro has already 1000+ programs on CD version and 2600+ packages / application on DVD version.
Nowadays Knoppix is mostly used mostly as USB Live Flash drive as a lot of people are dropping CD / DVD use (many servers doesn't have a CD / DVD Drive) and for USB Live Flash Linux distros tmpfs is also key technology used as this gives the end user an amazing fast experience (Desktop applications run much fasten on Live USBs when tmpfs is used than when the slow 7200 RPM HDDs are used).

Loading big parts of the distribution within RAM (with tmpfs from Linux Kernel 2.4+ onwards) is also heavily used by a lot of Cluster vendors in most of Clustered (Cloud) Linux based environemnts, cause TMPFS gives often speeds up improvements to x30 times and decreases greatly I/O HDD. FreeBSD users will be happy to know that TMPFS is already ported and could be used on from FreeBSD 7.0+ onward.

In this small article I will give you example use on how I use tmpfs to speed up our WordPress Websites which use WP Caching plugins such as W3 Total Cache and WP Super Cache
and Hyper Cache / WP Super Cache disk caching and MySQL server as a Database backend.
Below example is wordpress specific but since it can be easily applied to JoomlaDrupal or any other CMS out there that uses mySQL server to make a lot of CPU expensive memory hungry (LEFT JOIN) queries which end up using a slow 7200 RPM hard disk.


 

1. Preparing tmpfs partitions for WordPress File Cache directory
 

If you want to give tmpfs a test drive, I recommend you try to create / mount a 20 Megabyte partition. To create a tmpfs partition you don't need to use a tool like mkfs.ext3 / mkfs.ext4 as TMPFS is in reality a virtual filesystem that is mapped in the server system physical RAM (volatile memory). TMPFS is very nice because if you run out of free RAM system starts a combination of RAM use + some Hard disk SWAP 
The great thing about TMPFS is it never uses all of the available RAM and SWAP, which would not halt your server if TMPFS partition gets filled, but instead you will start getting the usual "Insufficient Disk Space", just like with a physical HDD parititon. RAMFS cares much less about server compared to TMPFS, because if RAMFS is historically older.

ramfs file systems cannot be limited in size like a disk base file system which is limited by it’s capacity, thus ramfs will continue using memory storage until the system runs out of RAM and likely crashes or becomes unresponsive. This is a problem if the application writing to the file system cannot be limited in total size, so in my opinion you better stay away from RAMFS except you have a good idea what you're doing. Another disadvantage of RAMFS compared to TMPFS is you cannot see the size of the file system in df and it can only be estimated by looking at the cached entry in free.

Note that before proceeding to use TMPFS or RAMFS you should know besides having advantages, there are certain serious disadvantage that if the server using tmpfs (in RAM) to store files crashes the customer might loose his data, therefore using RAM filesystems on Production servers is best to be used just for caching folders which are regularly synchronized with (rsync) to some folder to assure no data will be lost on server reboot or crash.

Memory of fast storage areas are ideally suited for applications which need repetitively small data areas for caching or using as temporary space such as Jira (Issue and Proejct Tracking Software) Indexing  As the data is lost when the machine reboots the tmpfs stored data must not be data of high importance as even scheduling backups cannot guarantee that all the data will be replicated in the even of a system crash.

To test mounting a tmpfs virtual (memory stored) filesystem issue:
 

mount -t tmpfs tmpfs -o size=256m /mnt/tmpfs


If you want to test mount a ramfs instead:

 

 mount -t ramfs -o size=256m ramfs /mnt/ramfs

 

debian-server:~#  mount |grep -i -E "ramfs|tmpfs"
tmpfs on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
udev on /dev type tmpfs (rw,mode=0755)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
tmpfs on /mnt/tmpfs type tmpfs (rw,size=256m)
ramfs on /mnt/ramfs type tmpfs (rw,size=256m)

 

Once mounted tmpfs can be used in the same way as any ext4 / reiserfs filesystem. In the same way to make mounts permanent, its necessery to add a line to /etc/fstab

To illustrate better a tmpfs use case on my blog running WordPress with W3TotalCache (W3TC) plugin cache folder in /var/www/blog/wp-content/w3tc to get advantage of tmpfs to store w3tc files.

a) Stop Apache

On Debian
 

debian-server:~# /etc/init.d/apache stop


On CentOS 
 

[root@centos ~]# /etc/init.d/httpd stop


b) Move w3tc dir to w3tc-bak

 

debian-server:~# cd /var/www/blog/wp-content/
debian-server:~# mv w3tc w3tc-bak

 

c) Create w3tc directory
 

debian-server:/var/www/blog/wp-content# mkdir w3tc
debian-server:/var/www/blog/wp-content# chown -R www-data:www-data w3tc


d) Add tmpfs record to /etc/fstab

My W3TC Cache didn't grow bigger than 2Gigabytes so I create a 2Giga directory for it by adding following in /etc/fstab 
 

debian-server:~# vim /etc/fstab

 

tmpfs /var/www/blog/wp-content/w3tc tmpfs defaults,size=2g,noexec,nosuid,uid=33,gid=33,mode=1755 0 0


You might also want to add the nr_inodes (option) to tmpfs while mounting. nr_inodes is the maximum inode for instance. Default is half the number of your physical RAM pages, (on a machine with highmem) the number of lowmem RAM page, some common option that should work is nr_inodes=5k, if you're unsure what this option does you can safely skip it 🙂

e) Mount new added tmpfs folder

Then to mount the newly added filesystem issue:
 

mount -a


Or if you're on a CentOS / RHEL server use httpd Apache user instead and whenever you have docroot and wordpress installed.

 

[root@centos ~]# chown -R apache:apache: w3tc


If you're using Apache SuPHP use whatever the UID / GID is proper.

On CentOS you will need to set proper UID and GID (UserID / GroupID), to find out which ones to to use check in /etc/passwd:
 

[root@centos ~]# grep -i apache /etc/passwd
apache:x:48:48:Apache:/var/www:/sbin/nologin


f) Move old w3tc cache from w3tc-bak to w3tc

 

debian-server:/var/www/blog/wp-content# mv w3tc-bak/* w3tc/

 

g) Start again Apache

On Debian:

 

debian-server:~# /etc/init.d/apache2 start

 


On CentOS:
 

[root@centos~]# /etc/init.d/httpd start

h) Keeping w3tc cache site folder synced

As I said earlier the biggest problem with caching (the reason why many hosting providers) and site admins refuse to use it is they might loose some data, to prevent data loss or at least mitigate the data loss to few minutes intervals it is a good idea to synchronize tmpfs kept folders somewhere to disk with rsync.

To achieve that use a cronjob like this:
 

debian-server:~# crontab -u root -e
*/5 * * * * /usr/bin/ionice -c3 -n7 /usr/bin/nice -n 19 /usr/bin/rsync -ah –stats –delete /var/www/blog/wp-content/w3tc/ /backups/tmpfs/cache/ 1>/dev/null


Note that you will need to have the /backups/tmpfs/cache folder existing, create it with:

 

debian-server:~# mkdir -p /backups/tmpfs/cache


You will also need to add a rsync synchronization from backupped folder to tmpfs (in case if the server gets accidently rebooted because it hanged or power outage), place in

/etc/rc.local

 

ionice -c3 -n7 nice -n 19 rsync -ahv –stats –delete /backups/tmpfs/cache/ /var/www/blog/wp-content/w3tc/ 1>/dev/null


(somewhere before exit 0) line
 

0 05 * * * /usr/bin/ionice -c3 -n7 /bin/nice -n 19 /usr/bin/rsync -ah –stats –delete /var/www/blog/wp-content/w3tc/ /backups/tmpfs/cache/ 1>/dev/null

 

 

2. Preparing tmpfs partitions for MySQL server temp File Cache directory


Its common that MySQL servers had to serve a lot of long and heavy SQL JOIN Queries mostly by related posts WP plugins such as (Zemanta Related Posts) and Contextual Related posts though MySQLs are well optimized  to work as much as efficient using mysql tuner (tuning primer) still often SQL servers get a lot of temp tables created to disk (about 25% to 30%) of all SQL queries use somehow HDD to serve queries and as this is very slow and there is file lock created the overall MySQL performance becomes sluggish at times to fix (resolve) that without playing with SQL code to optimize the slow queries the best way I found is by using TMPFS as MySQL temp folder.

To do so I create a TMPFS usually the size of 256 MB because this is usually enough for us, but other hosting companies might want to add bigger virtual temp disk:

a) Add tmpfs new dir to /etc/fstab

In /etc/fstab add below record with vim editor:
 

debian-server:~# vim /etc/fstab

 

tmpfs /var/mysqltmp tmpfs rw,gid=111,uid=108,size=256M,nr_inodes=10k,mode=0700 0 0

 

Note that the uid / and gid 105 and 114 are taken again from /etc/passwd

On Debian

debian-server:~# grep -i mysql /etc/passwd
mysql:x:108:111:MySQL Server,,,:/var/lib/mysql:/bin/false


On CentOS
 

[root@centos ~]# grep -i mysql /etc/passwd
mysql:x:27:27:MySQL Server:/var/lib/mysql:/bin/bash


b) Create folder /var/mysqltmp or whenever you want to place the tmpfs memory kept SQL folder

 

debian-server:~# mkdir /var/mysqltmp
debian-server:~# chown mysql:mysql /var/mysqltmp

 

debian-server:~# mount|grep -i tmpfs
tmpfs on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
udev on /dev type tmpfs (rw,mode=0755)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
tmpfs on /var/www/blog/wp-content/w3tc type tmpfs (rw,noexec,nosuid,size=2g,uid=33,gid=33,mode=1755)
tmpfs on /var/mysqltmp type tmpfs (rw,gid=108,uid=111,size=256M,nr_inodes=10k,mode=0700)


c) Add new path to tmpfs created folder in my.cnf 

Then  edit /etc/mysql/my.cnf

 

debian-server:~# vim /etc/mysql/my.cnf

[mysqld]
#
# * Basic Settings
#
user        = mysql
pid-file    = /var/run/mysqld/mysqld.pid
socket      = /var/run/mysqld/mysqld.sock
port        = 3306
basedir     = /usr
datadir     = /var/lib/mysql
tmpdir      = /var/mysqltmp

 

On CentOS edit and change tmpdir in same way within /etc/my.cnf


d) Finally Restart Apache and MySQL to make mysql start using new set tmpfs memory kept folder

On Debian:
 

debian-server:~# /etc/init.d/apache2 stop; /etc/init.d/mysql restart; /etc/init.d/apache2 start

On CentOS:
 

[root@centos ~]# /etc/init.d/httpd stop; /etc/init.d/mysqld restart; /etc/initd/httpd start


Now monitor your server and check your pagespeed increase for me such an optimization usually improves site performance so site becomes +50% faster, to see the difference you can test your website before applying tmpfs caching for site and after that by using Google PageInsight (PageSpeed) Online Test. Though this example is for MySQL and WordPress you can easily adopt the same for Joomla if you have Joomla Caching enabled to some folder, same goes for any other CMS such as Drupal that can take use of Disk Caching. Actually its a small secret of many Hosting providers that allow clients to create sites via CPanel and Kloxo this tmpfs optimizations are already used for sites and by this the provider is able to offer better website service on lower prices. VPS hosting providers also use heavy caching. A lot of people are using TMPFS also to accelerate Sites that have enabled Google Pagespeed as Cacher and accelerator, as PageSpeed module puts a heavy HDD I/O load that can easily stone the server. Many admins also choose to use TMPFS for  /tmp, /var/run, and /var/lock directories as this leads often to significant overall server services operations improvement.
Once you have tmpfs enabled, It is a good idea to periodically monitor your SWAP used space with (df -h), because if you allocate bigger tmpfs partitions than your physical memory and tmpfs's full size starts to be used your machine will start swapping heavily and this could have a very negative performance affect.
 

debian-server:~# df -h|grep -i tmpfs
tmpfs            3,9G     0   3,9G   0% /lib/init/rw
tmpfs            3,9G     0   3,9G   0% /dev/shm
tmpfs            2,0G  1,4G   712M  66% /var/www/blog/wp-content/w3tc
tmpfs            256M     0   256M   0% /mnt/tmpfs
tmpfs            256M  236K   256M   1% /var/mysqltmp

The applications of tmpfs to accelerate services is up to your imagination, so I will be glad to hear from other admins on any interesting other application or problems faced while using TMPFS.

 Enjoy! 🙂

Howto install XCache Debian on GNU / Linux to accelerate Apache Webserver – XCache Best alternative to outdated PHP cacher EAccelerator

Thursday, February 26th, 2015

xcache_install-and-enable-best-alternative-php-cacher-to-eaccelerator-logo
I was using Eaccelerator until recently on all Apache / PHP / MySQL  (LAMP) web-servers as a caching engine (Webserver accelerator) across all Debian GNU / Linux Lenny / Squeeze / Etch servers.
However recently, I've noticed in phpinfo output on some of the Debian hosts, that eaccelerator was loaded but showed:

 Caching Enabled false

eaccelerator_caching_enabled_false-phpinfo-screenshot-apache-debian-linux.

 

Our servers are quite busy serving about 50 000 to 100 000 requests and thus not having enabled caching puts a lot of extra load on the CPU and eats a lot of memory which were usually saved by eAccelerator.
Logically I tried fixing the issues following some Stackoverflow threads recommendations such as this one but didn't work I tried playing manually spending hours trying to make eaccelerator run again and as a final mean, I even tried to upgrade eaccelerator to newer version but noticed the latest available eaccelerator version 0.9.6 was 2.5 years old (from 03.09.2012). Thus while there is no new release, just make s so just to make sure I didn't break the module with (default Debian bundled distribution package which is also installed on the servers)  re-installed eAccelerator from source 

This didn't worked either and since I was totally pissed off by the worsened systems performance (CPU load increased with to 10-30%) per server, I looked for some alternatives I can use and in the mean time I learned a bit more about history of PHP Accelerators, I learned some interesting things such as that  ionCube (PHPA) was the  first PHP Accelerator Apache like module (encoding PHP code),  created in 2001, later it become inspirational for  birth to PHP-APC (Alternative PHP Cache) Apache module. 
There is also Zend Opcache PHP accelerator (available since PHP 5.5 onwards)  but since Zend OpCache caches well PHP Zend written PHP code and servers run PHP 5.4 + sites are not using Zend PHP Framewosk  this was an option.
Further investigation lead me to MMCache which is already too obsolete (latest release is from 2013), PHPExpress – PHP Encoder which  was said to run on Windows, Linux, FreeBSD, NetBSD, Mac OS X, and Solaris) but already looks dead as there were no new releases since January 2012) and finally Lighttpd's XCache.

To give you an idea on what exactly is the difference between Apache Webserver with PHP-APC Caching or other PHP Cacher enabled and the Standard way PHP Interprets PHP scripts below is a diagram:

php-apc-cache-how-php-caching-works-with-and-without-encoding-php-code-diagram

Obviously my short research shows that from all the available PHP Cache Encoder / Accelerators only ones that seemed to be recently updated (under active development) are APC and XCache.
I've already used PHP-APC earlier on some servers and was having having some random Apache Webservers crashes and weird empty pages with some PHP pages and besides that APC is known to give lower speed in PHP caching than Eaccelerator and XCache, leaving me with the only and logical choise to use XCACHE.

Here is how Xcache developers describe their opcacher:
 

XCache is a free, open source operation code cacher, it is designed to enhance the performance of PHP scripts execution on servers. It optimizes the performance by eliminating the compilation time of PHP code by caching the compiled version of code into the memory and this way the compiled version loads the PHP script directly from the memory. This will surety accelerate the page generation time by up to 5 times faster and also optimizes and increases many other aspects of php scripts and reduce website/server load.

 


Thanksfully XCache is shipped by default with all Debians (Etch /Lenny / Squeeze / Wheezy)  Linuces so to install it just run the standard apt cmd:
 

apt-get install –yes php5-xcache


Then to enable XCache all I had to do is edit /etc/php5/apache2/php.ini and place below code
 

debian-server:~# vim /etc/php5/apache2/php.ini

 

[xcache-common]
;; install as zend extension (recommended), normally "$extension_dir/xcache.so"
;;zend_extension = /usr/lib/php5/20100525/xcache.so

 

[xcache.admin]
xcache.admin.enable_auth = On
; Configure this to use admin pages
; xcache.admin.user = "mOo"
; xcache.admin.pass = md5($your_password)
; xcache.admin.pass = ""

[xcache]
; ini only settings, all the values here is default unless explained

; select low level shm/allocator scheme implemenation
xcache.shm_scheme =        "mmap"
; to disable: xcache.size=0
; to enable : xcache.size=64M etc (any size > 0) and your system mmap allows
xcache.size  =                16M
; set to cpu count (cat /proc/cpuinfo |grep -c processor)
xcache.count =                 1
; just a hash hints, you can always store count(items) > slots
xcache.slots =                8K
; ttl of the cache item, 0=forever
xcache.ttl   =                 0
; interval of gc scanning expired items, 0=no scan, other values is in seconds
xcache.gc_interval =           0
; same as aboves but for variable cache

Note that Debian location which instructs xcache to load in Apache as a module is xcache.ini – e.g. /usr/share/php5/xcache/xcache.ini, so instead of placing above configuration right into php.ini you might prefer to place it in xcache.ini (though I personally prefer php.ini) because it is easier for me to later control how PHP behaves from single location.

To test whether XCache is enabled for Apache Webserver:

Create phpinfo.php somewhere in DocumentRoot (in my case this was /var/www/php_info.php)

debian-server:~# vim /var/www/php_info.php

 

<php?
phpinfo()
?>


When you access the php_info.php in browser you will get XCache loaded as in below screenshot:

 

xcache_loaded-in-php-apache-phpinfo-output-debian-gnu-linux-server

To Test whether Xcache is enabled also for PHP CLI (applications set to run as a crontab – cronjob) :
 

debian-server:~# php -v
PHP 5.4.37-1~dotdeb.0 (cli) (built: Feb  2 2015 05:03:00)
Copyright (c) 1997-2014 The PHP Group
Zend Engine v2.4.0, Copyright (c) 1998-2014 Zend Technologies
    with XCache v3.2.0, Copyright (c) 2005-2014, by mOo
    with XCache Cacher v3.2.0, Copyright (c) 2005-2014, by mOo

 

Once it is tested as successful install you might want to enable the XCache admin (which is disabled by default), to enable XCache Admin on Debian you need to generate new password for it first like so:

 

echo -n "xcache_rulez" | md5sum
acbf5ba4a44f03058aa0ad11e0a6b645

 


Then you need to add in /etc/php5/mods-available/xcache.ini

debian-server:~# vim /etc/php5/mods-available/xcache.ini
[xcache.admin]
xcache.admin.enable_auth = On
; Configure this to use admin pages
 xcache.admin.user = "admin"
; xcache.admin.pass = md5($your_password)
 xcache.admin.pass = "change_with_above_generated_password_here"

 

To enable admin and be able to access it in a browser (if you're using as a documentroot /var/www/ and docroot supports interpretting php scripts and (has AllowOverride All) enabled to also support htaccess authentication do:
 

debian-server:~# cd /var/www/
debian-server:~# ln -sf /usr/share/xcache/htdocs/ xcache

When you access http://your-url-address.com/xcache/ you should see in browser some statistics along with all configured xcache options:

xcacher-admin-on-debian-gnu-linux-in-chrome-browser-screenshot-enable-xcacher-admin-howto

If you have time you can play with the options and get some speed minor speed improvements. The overall increase in page opening XCache should give you is between 100% – 190% !

Enjoy 🙂

Generating Static Source Code Auditing reports with Spike PHP Security Audit Tool

Saturday, April 24th, 2010

I’m conducting a PHP Audit on a server in relation to that one of the audit criterias I follow is a
Static PHP Source Code Auditing of the php files source code located physically on the Linux server.
Auditing a tons of source code manually is a kind of impossible task, therefore I needed a quick way to at least
partly automate or fully automate the PHP applications source code.
A quick search in Google pointed me to a php application tool – Spike Security Audit .
This small application PHP written app is quite handy. It is able to either check a certain php source code file for WARNINGS or ERRORS or do a complete security source code analysis of a bunch of PHP files in a directory including all the other php source files in subdirectories.

After executed the PHP Security Audit Tool generates a nice source code analysis report in html that can easily be later observed with some Browser.

The use of the tool is pretty straight forward, all you have to do is download it from Spikeforge – the project’s official webpage and unzip it e.g.


debian-server:~# wget http://developer.spikesource.com/frs/download.php/136/spike_phpSecAudit_0.27.zip
debian-server:~# unzip spike_phpSecAudit_0.27.zip

Then you have to invoke the run.php with the php cli, that you need to have installed first.
If you don’t have the php cli yet please install it with the command:


debian-server:~# apt-get install php5-cli

Now you have to execute the run.php script bundled with the spike php security audit program source code.


debian-server:~# php run.php

Please specify a source directory/file using –src option.

Usage run.php options

Options:
–src Root of the source directory tree or a file.
–exclude [Optional] A directory or file that needs to be excluded.
–format [Optional] Output format (html/text). Defaults to ‘html’.
–outdir [Optional] Report Directory. Defaults to ‘./style-report’.
–help Display this usage information.

As you can see the spike php security audit has only few command line options and they’re quite easily understandable.
However in my case I had to audit a couple of directories which contained source code.
I also wanted the generated reports to be cyclic, on let’s say per daily basis cause I wanted to have the PHP applicaiton analysis generated on a daily basis.
In that reason I decided to write a small shell script that would aid the usage of php spike audit, I’ve called the script code-analysis.sh

The usage of the Automation source code analysis script for PHP Spike Audit can be downloaded here
The script has a few configuration options that you might need to modify before you can put it to execute on a crontab.

This are:


# Specify your domain name on which php spike audit reports will be accessed
domain_name='yourdomainname.com';
# put here the location where phpspike run.php execute is located
spike_phpsec=/usr/local/spike_phpSecAudit_0.27/run.php;
# specify here which will be the directory where the php source code analysis reports will be stored by php spike
log_dir=/root/code-analysis/;
# in that part you have to specify the physical location of the php cli it's located by default in /usr/bin/php on Debian GNU Linux.
php_bin=/usr/bin/php;
# the directory below should be set to a directory where the reports that will be visible from the webserver will be stored
www_dir=/var/www/code-analysis;

# in the variables

directory[1]=’/home/source-code1/’; ..
directory[2]=”; ..

# you should configure the directories containing php source code to be audited by the php spike audit tool.

After you have prepared the code-analysis.sh script with your custom likings, you can now put it to be executed periodically
using crontab or some other unix system scheduler of choice.

To do that edit your root crontab.

crontab -u root -e

and put in it.

# code analysis results
05 3 * * * /usr/local/bin/code-analysis.sh >/dev/null 2>&1

Now hopefully you can edit your /etc/apache2/apache2.conf or your httpd.conf depending on your linux or unix architecture and make a Alias like:


Alias /code-analysis "/var/www/code-analysis"

Now your php source code analysis from the php spike audit tool will be generated daily.
You will be able to access them via web using http://yourdomain.com/code-analysis/

That way, you can review your php source code written or changed in your php applications on daily basis and you can a way easily track your coding mistakes, as well as track for possible security issues in your code.

For the sake of security I’ve also decided to protect the /code-analysis Apache directory with a password using the following .htaccess file:


AuthUserFile /var/www/code-analysis/.htpasswd
AuthGroupFile /dev/null
AuthName "Login to access PHP Source Code Analysis"
AuthType Basic

< Limit GET >
require valid-user
< /Limit >

If you decide to protect yours as well you have to also generate the .htpasswd file using the following command:


debian-server:~# htpasswd -c /var/www/code-analysis/.htpasswd admin

You will be asked for a password. The code-analysis.sh script will also take care to generate an html file for you including links to reports to all the php source code audited directories reports.

Now accessing http://yourdomain.com/code-analysis/ will give you shiny look to the php source applications generated reports .

Installing EEMame to play MAME games on Nokia 9300i / Turn your Nokia mobile to arcade game statition

Monday, May 31st, 2010

EEMame Nokia 9300i

Since I’m keen on old school arcade games I checked online if I can install and play MAME (Multimedia Arcade Machine Emulator) games (roms) to my Nokia 9300i mobile.
The information on the topic on the Net is pretty much muddled so it took me a while until I found that in order to install a MAME port for Nokia 9300i I will have to use EEMame – MAME for Symbian Mobile Phones .
The first thing I came across before I finally found EEMame was EMame 9210 .
Emame is a port of Mame that is compatible with Nokia 9300i since the 9300i mobile has backward compatibility with the older 9210 phone.
To save memory since the Nokia 9210 has low memory capacity the Mame 9210 application is actually separated in 4 applications each of which containing a set of drivers for a number of mame rom game files.:
The whole application Emame9210All.sis is separated into the following parts:

EMame9210Set1.sis
EMame9210Set2.sisEMame9210Set3.sis
EMame9210Set4.sis

For convenience the developers has provided also a .sis file containing all the up-mentioned 4 parts in one .sis archive
For some convenience I have created a mirror from which you can download EMame9210All.SIS

Though the Emame9210 would install on the Nokia 9300i and you’ll be able to run each of the 4 exe files from the Nokia file manager I couldn’t make the application work with any of the listed roms that are marked as a tested on the Emame9210.
Honestly I didn’t really spend much time trying, so it could be my fault that I couldn’t bring the Emame9210 on my 9300i mobile. Be aware that trying to run some rom files downloaded from romnation.net and listed as compatible with the 9210 arcade emulator led the Emame9210 programs to crash.
So assume the Emame9210 is not really compatible with the Nokia 9300 phone. Anyways this first time though mournful was just a plunge-board to the “real deal”, e.g. the real joy experienced when I found out that the EEMame port is available for Nokia 9300i
To install the EEMame on my Nokia 9300i I downloaded and installed the eemame-series80-1.1.SIS . The file is also available through EEmame’s official website download section along with few other EEmame for a few other Motorolla and Nokia powered devices.

Another thing I really liked about EEMame is that it’s released under the GNU General Public License

So far so good ’till now I was having a complete working version of MAME to my Nokia 9300i mobile but I was lacking any games and I was absolutely lazy to scrape through the internet to find some working rom files for the EEMame, not to mention that only a exact set of rom files is compatible to the device and you have to check and download the compatible games one by one … this is pretty much insane especially if you’re a busy man as I am.
I assumed somebody has already done the hard task of downloading and creating a pack with rom files that run on the EEMame so I spend approximately some half an hour to look for a preliminary prepared pack of rom files that would run on the EEMame mobile (Multiple Arcade Machine Emulator).
The original announce for the availability for download of eemame 218 rom games which are compatible with EEMame could be red here

You can download MAME_S60v3_and_working_ROMSET_by_herbalb.rar here

Herein I will include herbalb original message found along with his 218 rom games pack for EEMAME :

Some time ago I made a romset that includes 1320 of 1321 Roms known to work with EEMAME (also included). Hope some of you will like it and have fun playing these original arcade games (i.e. Wonderboy, Ghost N Goblins, Joust, Arkanoid, 1943, Burger Time, Contra ...).
By the way, when starting a game and you read 'press OK to continue' just push left and then right on the directional pad on your phone and the game will start.

I tested them (many of them) on my N95.
You can also try this version of EEMame to use with the Set above (I have not tested this version as i am using the one includet in the set)Happy new year and peace to everyone.

herbalb

NOTE: I am happy if you share it with others but please do not say it would be your own work. It took me hours to do find all necessary games for this set, so please be social, thanks.

As you can see in herbalb’s message the ROM games for EEMame are not tested with other mobile phones except the N95.
I downloaded and tested his EEMAME rom pack set and I have to confirm almost all the game are loading with EEMame perfectly fine.
However there is two minor down-sides of the EEMame on Nokia 9300i. First you will probably have to play the rom games without a sound, because when sound is enabled almost all the games will work slow as hell, and second most of the MAME emulated games will occupy just a small portion of your screen and you won’t be able to enjoy the joy of playing the game on a full wide screen on your cellphone.
Anyways life is not perfectly anywhere, being able to play all this wonderful oldschool arcade directly on your Nokia 9300i mobile turns your mobile into a sophisticated game station and guarantees you a lot of fun.
I have prepared a list of all the rom files included with MAME_S60v3_and_working_ROMSET_by_herbalb.rar, you can check the whole list of roms available for EEMame on Nokia 9300i here

I have also made some few modifications in the readme of the herbalb’s archive and have included the necessery sis file to install and run EEMAME on Nokia 9300i the new archive can be downloaded here.

Just in case if you need to download some specific rom files from the whole collection please select your preferred EEMame ROM file here
Well, That’s all folks! All left now is to truly enjoy your classic nitendo & arcade games playable directly on your Nokia 9300i mobile! 🙂

Save data from failing hard disk on Linux – Rescuing data from failing disk with bad blocks

Wednesday, April 16th, 2014

save-data-from-failing-hard-drive-data-recovery-badblocks-linux_1.jpg
Sooner or later your Linux Desktop or Linux server hard drive will start breaking up, whether you have a hardware or software RAID 1, 6 or 10 you can  and good hard disk health monitoring software you can react on time but sometimes as admins we have to take care of old servers which either have RAID 0 or missing RAID configuration and or disk firmware is unable to recognize failing blocks on time and remap them. Thus it is quite useful to have techniques to save data from failing hard disk drives with physical badblocks.

With ddrescue tool there is still hope for your Linux data though disk is full of unrecoverable I/O errors.

apt-cache show ddrescue
 

apt-cache show ddrescue|grep -i description -A 12

Description: copy data from one file or block device to another
 dd_rescue is a tool to help you to save data from crashed
 partition. Like dd, dd_rescue does copy data from one file or
 block device to another. But dd_rescue does not abort on errors
 on the input file (unless you specify a maximum error number).
 It uses two block sizes, a large (soft) block size and a small
 (hard) block size. In case of errors, the size falls back to the
 small one and is promoted again after a while without errors.
 If the copying process is interrupted by the user it is possible
 to continue at any position later. It also does not truncate
 the output file (unless asked to). It allows you to start from
 the end of a file and move backwards as well. dd_rescue does
 not provide character conversions.

 

To use ddrescue for saving data first thing is to shutdown the Linux host boot the system with a Rescue LiveCD like SystemRescueCD – (Linux system rescue disk), Knoppix (Most famous bootable LiveCD / LiveDVD), Ubuntu Rescue Remix or BackTrack LiveCD – (A security centered "hackers" distro which can be used also for forensics and data recovery), then mount the failing disk (I assume disk is still mountable :). Note that it is very important to mount the disk as read only, because any write operation on hard drive increases chance that it completely becomes unusable before saving your data!

To make backup of your whole hard disk data to secondary mounted disk into /mnt/second_disk

# mkdir /mnt/second_disk/rescue
# mount /dev/sda2 /mnt/second_disk/rescue
# dd_rescue -d -r 10 /dev/sda1 /mnt/second_disk/rescue/backup.img
# mount -o loop /mnt/second_disk/rescue/backup.img

In above example change /dev/sda2 to whatever your hard drive device is named.

Whether you have already an identical secondary drive attached to the Linux host and you would like to copy whole failing Linux partition (/dev/sda) to the identical drive (/dev/sdb) issue:

ddrescue -d -f -r3 /dev/sda /dev/sdb /media/PNY_usb/rescue.logfile

If you got just a few unreadable files and you would like to recover only them then run ddrescue just on the damaged files:

ddrescue -d –R -r 100 /damaged/disk/some_dir/damaged_file /mnt/secondary_disk/some_dir/recoveredfile

-d instructs to use direct I/O
-R retrims the error area on each retry
-r 100 sets the retry limit to 100 (tries to read data 100 times before resign)

Of course this is not always working as on some HDDs recovery is impossible due to hard physical damages, if above command can't recover a file in 10 attempts it is very likely that it never succeeds …

A small note to make here is that there is another tool dd_rescue (make sure you don't confuse them) – which is also for recovery but GNU ddrescue performs better with recovery.
How ddrescue works is it keeps track of the bad sectors, and go back and try to do a slow read of that data in order to read them.
By the way BSD users would happy to know there is ddrescue port already, so data recovery on BSDs *NIX filesystems if you're a Windows user you can use ddrescue to recover data too via Cygwin.
Of course final data recovery is also very much into God's hands so before launching ddrescue, don't forget to say a prayer 🙂

Make Viber calls with no smartphone from Mobile to PC and from PC to Mobile – Bluestacks install android mobile apps on PC

Thursday, April 24th, 2014

Viber-for-smartphones-connect-freely-through-internet-voip-on-your-mobile

Since I've bought ZTE smat phone and I have Android on it, decided to install   Viber – iOS, Android and Desktop PC – Free Calls, Text and Picture sharing through the internet app. Viber is used by a lot of my people including many friends already so I installed it as well to be possible to speak for free with close friends …

Why Viber?


What makes this nifty app so great is its capability to make free calls over mobile phones through the Internet Viber.
Viber saves you a lot of money as calls are handled only through the Internet (you need Wifi on your mobile or Mobile 3G Internet access on phone) and you don't need to pay to your mobile operator 0.10 – 0.15 euro / cents per minute. Besides being Free another advantage of Viber is conversations sound quality which is much better than a regular phone call

Viber doesn't need a special registration, but as (login) identificator uses your mobile phone number – you just need to have a working Mobile operator phone num. Once registered under a number even if you change your mobile sim card to other operator (for example moving from country to country) still the Viber account will continue work. Another good reason to use Viber is it makes possible price free calls between different countries (for example if you travel a lot and you want to regularly speak with your wife) – in my case right now I'm in Bulgaria and my wife is in Belarus, so to save money and keep talking daily we use Viber daily.

What Devices and Operating System Viber Supports and what is Viber advantages / disadvantages ?


Another reason why Viber is so great is its multi-platform support it works on iPhone, Blackberry, Windows Phone, Nokia (Symbian), Windows, Mac OS and even (Korean own OS-ed) Bada devices. Some might argue that Viber is inferior to Skype and interms of Voice and Video quality its better because of its enhanced HD voice enhanced codecs, besides that Viber's video is still in Beta. However Viber has one big advantage it makes easy possible to reach people using just their Mobile Phone numbers where in Skype it takes time and effort to register in Skype install application on your Mobile keep yourself logged in in Skype and have all contacts previously added, all this happens automatically in Viber in time of installation of Viber App on your mobile.
 

Which Is Cheaper Viber or Skype?

Skype_VS_Viber-VOIP-Prices-which-is-cheaper-skype-or-viber


Once installed Viber could integrate itself with rest of your Mobile OS Call Manager and in time of call a friend number you have the opportunity to make it free Viber call. Viber are also selling Viber Credits so if you want to use your Viber Voice Over IP you can call external mobile operator numbers on a very very cheap price. Viber Calls to landline or mobile phones could be up to 400% cheaper than Skype! Whether you own a Smartphone it will be nice to give Viber a try.

Viber – How to make Phone calls between Desktop PC and Smarphone Mobile

 

One not so standard Viber use is to make Viber calls with no smartphone (at hand) from PC to another Viber equipped Mobile and vice versa.
I needed to make Viber calls from my ZTE Android running mobile to my wife's MacBook Air PC because her mobile is an old Nokia running obscure Symbian version which is not supporting Viber + she doesn't have an Internet access tariff switched on her mobile.

Here is what I had to do to make Phone calls between my Mobile Viber App and my wife's MacbookAir Notebook PC:
 

  • Install BlueStacks Web App Player

     

     

     

    BlueStacks_emulate-google-appstore-on-Windows-and-Mac-OS-android-emulator_Logo
    BlueStacks App Player is a software designed to enable Android applications to run on Windows PC, Apple Macintosh Computers and Windows tablets. BlueStacks is something like (VMware, Qemu) Virtual Machine which allows you to install and run any Android App on your Desktop PC.
    Its curious that app was created by Rosen Sharma in 2008 an ex CTO (Chief Technology Officer) of McAfee
     

  •  A mobile phone with a working SIM card (Nokia 6310 or any old mobile no need to be a smartphone
     
  • Desktop PC with Windows 7, 8 or PC with Mac OS


Install Bluestacks

BlueStacks is needed in order to emulate a smartphone on your PC, therefore once setupped Bluestacks. Launch it and  inside its necessary to login with your Gmail (Google Account) in order to allow access to Google Play Appstore on your PC.
viber with no mobile phone bluestacks
 

Installing and Verifying Viber

This is the most crucial and tricky part in order to make Viber working on any device you need to receive a special Viber verification code, you need to fill in this code to confirm Viber installation on PC. Here I assume you have BlueStacks running with Viber Application installed.

viber-running-under-bluestacks-on-windows-7-8-screenshot

First will be prompted to Agree with Terms and Conditions and provide Mobile Phone number for verification. Tell the Viber app that you have a smartphone with Viber already when prompted. After receving Viber Verification Code you need to fill in this code into BlueStacks Window (inside Viber should be running), go further to next step and you should be done with Desktop PC Viber number registration.

N.B. ! One brackets to open here is you need to have a working Mobile Phone number where you will receive the verification code as SMS, otherwise you cannot get the verification. On your filled in mobile phone number you will get the verification code as SMS.

Making Viber Calls to (Windows Mac) PC without Smartphone

There is no more further need for BlueStacks so you can uninstall it, however I preferred to keep it as its useful to be able to install Android Applications straight on your Desktop PC. To start using Viber on Desktop, just launch Viber application (not through BlueStacks) but the direct install.

Use Viber dial pad to dial your desired remote Smartphone number with Viber equipped.
Enjoy the free Internet calls ! 🙂