Posts Tagged ‘config’

Nginx increase security by putting websites into Linux jails howto

Monday, August 27th, 2018

linux-jail-nginx-webserver-increase-security-by-putting-it-and-its-data-into-jail-environment

If you're sysadmining a large numbers of shared hosted websites which use Nginx Webserver to interpret PHP scripts and serve HTML, Javascript, CSS … whatever data.

You realize the high amount of risk that comes with a possible successful security breach / hack into a server by a malicious cracker. Compromising Nginx Webserver by an intruder automatically would mean that not only all users web data will get compromised, but the attacker would get an immediate access to other data such as Email or SQL (if the server is running multiple services).

Nowadays it is not so common thing to have a multiple shared websites on the same server together with other services, but historically there are many legacy servers / webservers left which host some 50 or 100+ websites.

Of course the best thing to do is to isolate each and every website into a separate Virtual Container however as this is a lot of work and small and mid-sized companies refuse to spend money on mostly anything this might be not an option for you.

Considering that this might be your case and you're running Nginx either as a Load Balancing, Reverse Proxy server etc. , even though Nginx is considered to be among the most secure webservers out there, there is absolutely no gurantee it would not get hacked and the server wouldn't get rooted by a script kiddie freak that just got in darknet some 0day exploit.

To minimize the impact of a possible Webserver hack it is a good idea to place all websites into Linux Jails.

linux-jail-simple-explained-diagram-chroot-jail

For those who hear about Linux Jail for a first time,
chroot() jail is a way to isolate a process / processes and its forked children from the rest of the *nix system. It should / could be used only for UNIX processes that aren't running as root (administrator user), because of the fact the superuser could break out (escape) the jail pretty easily.

Jailing processes is a concept that is pretty old that was first time introduced in UNIX version 7 back in the distant year 1979, and it was first implemented into BSD Operating System ver. 4.2 by Bill Joy (a notorious computer scientist and co-founder of Sun Microsystems). Its original use for the creation of so called HoneyPot – a computer security mechanism set to detect, deflect, or, in some manner, counteract attempts at unauthorized use of information systems that appears completely legimit service or part of website whose only goal is to track, isolate, and monitor intruders, a very similar to police string operations (baiting) of the suspect. It is pretty much like а bait set to collect the fish (which in this  case is the possible cracker).

linux-chroot-jail-environment-explained-jailing-hackers-and-intruders-unix

BSD Jails nowadays became very popular as iPhones environment where applications are deployed are inside a customly created chroot jail, the principle is exactly the same as in Linux.

But anyways enough talk, let's create a new jail and deploy set of system binaries for our Nginx installation, here is the things you will need:

1. You need to have set a directory where a copy of /bin/ls /bin/bash /bin/,  /bin/cat … /usr/bin binaries /lib and other base system Linux system binaries copy will reside.

 

server:~# mkdir -p /usr/local/chroot/nginx

 


2. You need to create the isolated environment backbone structure /etc/ , /dev, /var/, /usr/, /lib64/ (in case if deploying on 64 bit architecture Operating System).

 

server:~# export DIR_N=/usr/local/chroot/nginx;
server:~# mkdir -p $DIR_N/etc
server:~# mkdir -p $DIR_N/dev
server:~# mkdir -p $DIR_N/var
server:~# mkdir -p $DIR_N/usr
server:~# mkdir -p $DIR_N/usr/local/nginx
server:~# mkdir -p $DIR_N/tmp
server:~# chmod 1777 $DIR_N/tmp
server:~# mkdir -p $DIR_N/var/tmp
server:~# chmod 1777 $DIR_N/var/tmp
server:~# mkdir -p $DIR_N/lib64
server:~# mkdir -p $DIR_N/usr/local/

 

3. Create required device files for the new chroot environment

 

server:~# /bin/mknod -m 0666 $D/dev/null c 1 3
server:~# /bin/mknod -m 0666 $D/dev/random c 1 8
server:~# /bin/mknod -m 0444 $D/dev/urandom c 1 9

 

mknod COMMAND is used instead of the usual /bin/touch command to create block or character special files.

Once create the permissions of /usr/local/chroot/nginx/{dev/null, dev/random, dev/urandom} have to be look like so:

 

server:~# ls -l /usr/local/chroot/nginx/dev/{null,random,urandom}
crw-rw-rw- 1 root root 1, 3 Aug 17 09:13 /dev/null
crw-rw-rw- 1 root root 1, 8 Aug 17 09:13 /dev/random
crw-rw-rw- 1 root root 1, 9 Aug 17 09:13 /dev/urandom

 

4. Install nginx files into the chroot directory (copy all files of current nginx installation into the jail)
 

If your NGINX webserver installation was installed from source to keep it latest
and is installed in lets say, directory location /usr/local/nginx you have to copy /usr/local/nginx to /usr/local/chroot/nginx/usr/local/nginx, i.e:

 

server:~# /bin/cp -varf /usr/local/nginx/* /usr/local/chroot/nginx/usr/local/nginx

 


5. Copy necessery Linux system libraries to newly created jail
 

NGINX webserver is compiled to depend on various libraries from Linux system root e.g. /lib/* and /lib64/* therefore in order to the server work inside the chroot-ed environment you need to transfer this libraries to the jail folder /usr/local/chroot/nginx

If you are curious to find out which libraries exactly is nginx binary dependent on run:

server:~# ldd /usr/local/nginx/usr/local/nginx/sbin/nginx

        linux-vdso.so.1 (0x00007ffe3e952000)
        libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f2b4762c000)
        libcrypt.so.1 => /lib/x86_64-linux-gnu/libcrypt.so.1 (0x00007f2b473f4000)
        libpcre.so.3 => /lib/x86_64-linux-gnu/libpcre.so.3 (0x00007f2b47181000)
        libcrypto.so.0.9.8 => /usr/local/lib/libcrypto.so.0.9.8 (0x00007f2b46ddf000)
        libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f2b46bc5000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f2b46826000)
        /lib64/ld-linux-x86-64.so.2 (0x00007f2b47849000)
        libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f2b46622000)


The best way is to copy only the libraries in the list from ldd command for best security, like so:

 

server: ~# cp -rpf /lib/x86_64-linux-gnu/libthread.so.0 /usr/local/chroot/nginx/lib/*
server: ~# cp -rpf library chroot_location

etc.

 

However if you're in a hurry (not a recommended practice) and you don't care for maximum security anyways (you don't worry the jail could be exploited from some of the many lib files not used by nginx and you don't  about HDD space), you can also copy whole /lib into the jail, like so:

 

server: ~# cp -rpf /lib/ /usr/local/chroot/nginx/usr/local/nginx/lib

 

NOTE! Once again copy whole /lib directory is a very bad practice but for a time pushing activities sometimes you can do it …


6. Copy /etc/ some base files and ld.so.conf.d , prelink.conf.d directories to jail environment
 

 

server:~# cp -rfv /etc/{group,prelink.cache,services,adjtime,shells,gshadow,shadow,hosts.deny,localtime,nsswitch.conf,nscd.conf,prelink.conf,protocols,hosts,passwd,ld.so.cache,ld.so.conf,resolv.conf,host.conf}  \
/usr/local/chroot/nginx/usr/local/nginx/etc

 

server:~# cp -avr /etc/{ld.so.conf.d,prelink.conf.d} /usr/local/chroot/nginx/nginx/etc


7. Copy HTML, CSS, Javascript websites data from the root directory to the chrooted nginx environment

 

server:~# nice -n 10 cp -rpf /usr/local/websites/ /usr/local/chroot/nginx/usr/local/


This could be really long if the websites are multiple gigabytes and million of files, but anyways the nice command should reduce a little bit the load on the server it is best practice to set some kind of temporary server maintenance page to show on the websites index in order to prevent the accessing server clients to not have interrupts (that's especially the case on older 7200 / 7400 RPM non-SSD HDDs.)
 

 

8. Stop old Nginx server outside of Chroot environment and start the new one inside the jail


a) Stop old nginx server

Either stop the old nginx using it start / stop / restart script inside /etc/init.d/nginx (if you have such installed) or directly kill the running webserver with:

 

server:~# killall -9 nginx

 

b) Test the chrooted nginx installation is correct and ready to run inside the chroot environment

 

server:~# /usr/sbin/chroot /usr/local/chroot/nginx /usr/local/nginx/nginx/sbin/nginx -t
server:~# /usr/sbin/chroot /usr/local/chroot/nginx /usr/local/nginx/nginx/sbin/nginx

 

c) Restart the chrooted nginx webserver – when necessery later

 

server:~# /usr/sbin/chroot /nginx /usr/local/chroot/nginx/sbin/nginx -s reload

 

d) Edit the chrooted nginx conf

If you need to edit nginx configuration, be aware that the chrooted NGINX will read its configuration from /usr/local/chroot/nginx/nginx/etc/conf/nginx.conf (i'm saying that if you by mistake forget and try to edit the old config that is usually under /usr/local/nginx/conf/nginx.conf

 

 

How to enable Gravis UltraSound in DOSBox for enhanced music experience in DOS programs and Games

Tuesday, October 31st, 2017

DOSBox

Gravis UltraSound Classic

 

Gravis UltraSound

Gravis UltraSound or GUS is a sound card for the IBM PC compatible systems.
It was lunched in 1992 and is notable for it's ability to use real-world sound recordings (wavetable) of a musical instruments rather than artificial computer-generated waveforms.
As one of my friends used to say back then: "it sounds like a CD".

To enable GUS in DOSBox all you need to do is:

1. Download the archive with the GUS files from https://alex.pc-freak.net/files/GUS/ULTRASND.zip. Extract the archive (there is already a directory in it so you don't have to create one) preferably where you keep your DOSBox stuff (like Games).

2. Find your DOSBox config file. Depending on the version or host OS, the dosbox conf file is located either inside the user profile folder or inside the same folder as dosbox.exe. In Windows 7 the config file is located at

"C:\Users\Fred\AppData\Local\VirtualStore\Program Files (x86)\dosbox.conf"

where "Fred" is your username.

In GNU/Linux it's in "/home/Fred/.dosbox/dosbox.conf" where "Fred" is your username.

The name of the conf file may also have dosbox version (for example –

"dosbox-0.74.conf").

Open it with a text editor like notepad (Windows) or equvalent for GNU/Linux (vi, Kate, gedit…). Locate "[gus]" section (without the quotes) and edit it so it looks like this:

[gus]
#      gus: Enable the Gravis Ultrasound emulation.
#  gusrate: Sample rate of Ultrasound emulation.
#           Possible values: 44100, 48000, 32000, 22050, 16000, 11025, 8000, 49716.
#  gusbase: The IO base address of the Gravis Ultrasound.
#           Possible values: 240, 220, 260, 280, 2a0, 2c0, 2e0, 300.
#   gusirq: The IRQ number of the Gravis Ultrasound.
#           Possible values: 5, 3, 7, 9, 10, 11, 12.
#   gusdma: The DMA channel of the Gravis Ultrasound.
#           Possible values: 3, 0, 1, 5, 6, 7.
# ultradir: Path to Ultrasound directory. In this directory
#           there should be a MIDI directory that contains
#           the patch files for GUS playback. Patch sets used
#           with Timidity should work fine.

gus=true
gusrate=44100
gusbase=240
gusirq=5
gusdma=3
ultradir=C:\ULTRASND

Then save the dosbox conf file.

3. Start DOSBox and mount "ULTRASND" directory to "C:".

You can do that with

mount c (directory to ULTRASND)

For example if you have extracted the archive in "C:\Games" it has created "C:\Games\ULTRASND" and the command you will have to write in DOSBox is

mount c c:\Games

(example: if your game is in "C:\Games\Heroes2" and your GUS directory is "C:\Games\ULTRSND" (if you have extracted the archive "C:\Games\") then you "mount c c:\Games" and you are set)

or for GNU/Linux if you have extracted the archive in "/home/Fred/Games" it has created "/home/Fred/Games/ULTRASND" and the command you will have to write in DOSBox is

mount c /home/Fred/Games (where "Fred" is your user name).

(example: if your game is in "/home/Fred/Games/Heroes2" and your GUS directory is "/home/Fred/Games/ULTRSND" (if you have extracted the archive" /home/Fred/Games/") in  then you "mount c /home/Fred/Games" and you are set)

You can make this automatic so you don't have to write it everytime by adding this command in the end (bottom) part of your dosbox conf file and save it.

You're practicly ready. All you need to do now is set Gravis UltraSound in your game or application setup (for example with the file "setup.exe") with IO: 240, IRQ 5 and DMA 3. If you prefer you previous sound card you can do that by selecting it again from the setup without disabling GUS from the dosbox conf file.

Happy listening!

Gravis Ultrasound

 

Article written by Alex

Fix dosbox – setting: cycles=auto. If the game runs too fast try a fixed cycles amount in DOSBox’s options. Exit to error: DRC64:Unhandled memory reference

Thursday, October 12th, 2017

fix-dosbox-error-setting-cycles-auto-game-runs-too-fast-exit-err-drc64-unhandled-memory-reference

I've recently installed Debian GNU / Linux 9.1 Stretch and on Ubuntu 16.10 Yakkety Yak and as an old school true gamer addict decided to play some games to recall the good old memories from the past of the glorious DOS games times, when all was simple people was real and there was no terrible people dividers such as Facebook  / GooglePlus, no skype fuzzy craziness and no people watching all time at their mobile smart phones like zoombies .

Well anyways, so I wanted to play my favourite DOS games Terminal Velocity, StarGunner, Raptor, Heroes of Might and Magic 2, Doom II, Duke 3d etc. etc. the list goes on and on – BTW What's your favourite old school DOS Game??

So I issues in Terminal:

$ dosbox TV.EXE

DOSBox version 0.74
Copyright 2002-2010 DOSBox Team, published under GNU GPL.

CONFIG:Loading primary settings from config file /home/zetathon/.dosbox/dosbox-0.74.conf
MIXER:Got different values from SDL: freq 44100, blocksize 512
ALSA:Can't subscribe to MIDI port (65:0) nor (17:0)
MIDI:Opened device:none
DOSBox switched to max cycles, because of the setting: cycles=auto. If    the game runs too fast try a fixed cycles amount in DOSBox's options.
Exit to error: DRC64:Unhandled memory reference

 

So what is the solution to  Exit to error: DRC64:Unhandled memory reference
error and why it happens?

Well, as the error clearly states the whole problem
comes from a default dosbox dos emulator configuration, that's the
setting:
 

cycles=auto


Perhaps the CPU beat of a Core I7 CPUs is too strong for some of the old games which are expecting a slower PC with less memory that's why the exception

Exit to Error: DRC64:Unhandled memory reference
is spit out by Dosemu.

So how to solve DRC64:Unhandled memory reference dosemu error?

By default DOSBOX places its configuration at  Linux / BSD / *nix-es at home folder /dosbox – e.g. ~/.dosbox/ the naming of dosbox.conf might differ according to dosbox version and the respective Linux / BSD distro, on Debian and Ubuntu Linux usually the naming includes a version number.

On Debian 9 Strecth Linux dosbox config is at ~/.dosbox/dosbox-0.74.conf

Edit the file
 

$ vim ~/.dosbox/dosbox-0.74.conf


and change inside the value for:

 

 

 

core=auto

to

core=normal

Then give dosbox with the erroring game another try, it worked for me
for me and everything seemed to run fine.

I've only run a handful of games but so far it seems to be working well.

If it does work but performance is degraded and tooks a huch hit on Gameplay you better try to substitute
 

core=normal

to
 

core=simple


AND HOORAY IT WORKS AGAIN! THE GAME RUN SUCCESSFULLY JOY TO THE WORLD! 🙂

Make Apache webserver fix spelling mistyped URL errors and serve files case insensitive with mod_speling

Wednesday, July 16th, 2014

make_apache_fix_mistyped_spelling_urls_errors_and_serve_files_case_insensitive_mod_speling_logo
On most if not all modern GNU / Linux distributions, Apache webserver comes preinstalled with mod_speling.

What mod_speling does is it tries to find and serve files and directories for non-existing  (404 return code) urls with a similar name to passed URL. Other thing mod_speling does is it serves files case-insensitive, even though the UNIX / Linux filesystems are built to understand files case-sensitive.

mod_speling is a very useful module especially when files are being pushed (synchronized) to Apache visible from web document folder from operating systems like Windows whose filesystem doesn't store files case sensitive.

Let me give you a small example on M$ Windows a create file NewFile.html, NEWFILE.HTML, NeWfIlE.Html etc. are one and the same file newfile.html and not 3 different files like it is usually on UNIX / Linux filesystems.

If you happen to migrate old static Websites from Microsoft Internet Information Services (IIS) to UNIX / Linux based hosting. Often Html coders which create websites on Windows platform doesn't respect in website hyperlinks case-sensitive, because anyways Windows FS is case-insetive, thus moving the website to Linux host with Apache the website/s will end up with many 404 error pages, whose fixing for big static websites will be a real pain in the ass.

Also there might be need for mod_speling module enabled, for PHP / Python / Perl websites developed on MS Windows platform and tested on Windows host and then officially to be deployed on Linux.

Note that mod_speling name as a funny thing as actually the module is also converting mis-pelled / mis-typed Apache URLs:

If for example, someone tried to link to your website from a forum mistyping the URL address with mod_speling the mistyped URL could still be handled to open the real existing URL:

Lets say you have URL:
 

http://your-domain.com/files/what-Ever-fle.php


and the actual URL is:

http://your-domain.com/files/what-Ever-file.php

 

mod_speling will make Apache scan in /files/ for any files with similar name to what-Ever-fle.php and will open any similar matched file name, preventing you from the normal 404 error and therefore often serving exactly what it has to. Of course such a behavior could be unwanted in same cases for CMSes, which depend on 404 error code for proper operating, so be very sure when configuring mod_speling that this is exactly what you need.

mod_speling can be also useful sometimes for Search Engine Optimization – SEO, as it will show less 404 pages to Crawler search engine bots.

1. Enable mod_speling module on Debian GNU / Linux and Ubuntu

Enabling mod_speling in Apache in Debian / Ubuntu etc. debian based Linuxes is done with either creating symlink from /etc/apache2/mods-available/speling.load to /etc/apache2/mods-enabled/speling.load :
 

ln -sf /etc/apache2/mods-available/speling.load /etc/apache2/mods-enabled/speling.load

Or by using a2enmodDebian apache module enabling script:
 

a2ensite sitename


To enable mod_speling mis-speling resolve feature config directive is:

 

CheckSpelling on


To disable case sensitivity – as I said earlier helpful for migrations from Microsoft Windows hosts to Linux, use directive:

CheckCaseOnly on


To enable both use:

<IfModule mod_speling.c>
    CheckCaseOnly on
    CheckSpelling on
</IfModule>

Enabling mod_speling case-insensitivity and fixing mistypes in URL could be done from .htaccess, for any <Directory> (vhost) with enabled .htaccess with

AllowOverride All

To enable it for default set host in new Apache install place it in /etc/apache2/apache2.conf and /etc/apache2/sites-enabled/000-default

Then as usual to make the configuration changes take affect, restart Apache:
 

/etc/init.d/apache2 restart


2. Enablig mod_speling on CentOS, RHEL and Fedora Linux

 

Most of RPM based Linux distributions have already mod_speling by default in Apache, so there will be no need to explicitly enable the module within HTTPD.

To check whether mod_speling is already enabled in httpd issue:
 

/usr/sbin/httpd -M |grep -i mod_speling


If you don't get no output from command this means the module is not enabled. This is the case with CentOS Linux 6.5 for example …

To enable mod_speling on Apache level add in /etc/httpd/conf/httpd.conf

LoadModule speling_module modules/mod_speling.so

and restart webserver
 

/etc/init.d/httpd restart


If you get instead
 

/usr/sbin/httpd -M |grep -i mod_speling
speling_module (shared)

 

Then it is already loaded in HTTPD to enable the module for default domain add to /etc/httpd/conf/httpd.conf – within (<Directory "/var/www/html">),

<IfModule mod_speling.c>
    CheckCaseOnly on
    CheckSpelling on
</IfModule>

Or if you want to make it active for specific directories within /var/www/html/whatever-dir use either new <Directory ..> directive within Apache config, or enable .htaccess processing with AllowOverride All and place them in .htaccess . For complete mod_speling reference check on Apache's official website

Fix MySQL connection error – Host ” is blocked because of many connection errors; unblock with ‘mysqladmin flush-hosts’

Wednesday, July 2nd, 2014

fix-mysql-too-many-connection-errors-explained

If you get a MySQL error like:

Host '' is blocked because of many connection errors; unblock with 'mysqladmin flush-hosts'

This most likely means your PHP / Java whatever programming language application connecting to MySQL is failing to authenticate with the application created (existing) or that the application is trying too many connections to MySQL in a rate where MySQL server can't serve all the requests.

Some common errors for Too many Connection errors are:
 

  • Networking Problem
  • Server itself could be down
  • Authentication Problems
  • Maximum Connection Errors allowed.

The value of the max_connection_errors system variable determines how many successive interrupted connection requests are permitted to myqsl server.
 

Well anyways if you get the:

Host '' is blocked because of many connection errors; unblock with 'mysqladmin flush-hosts'

You can consider this a sure sign application connections to MySQLis logging a lot of error connections, for some reason.
This error could also appear on very busy websites where high amount of separete connections are used – I've seen the error occur on PHP websites whether mysql_pconnect(); is selected in favour of the prooved working mysql_connect();

The first thing to do before changing / increasing default set of max connection errors is to check how many max connection errors are set within MySQL?

For that connect with MySQL CLI and issue:
 

mysql> SHOW VARIABLES LIKE '%error%';


+——————–+————————————————————-+
| Variable_name      | Value                                                           |
+——————–+————————————————————-+
| error_count        | 0                                                                     |
| log_error          | /var/log/mysql//mysqld.log                                |
| max_connect_errors | 10000                                                      |
| max_error_count    | 64                                                               |
| slave_skip_errors  | OFF                                                             |
+——————–+————————————————————-+


A very useful mysql cli command in debugging max connection errors reached problem is

mysql> SHOW PROCESSLIST;

 

To solve the error, try to tune in /etc/my.cnf, /etc/mysql/my.cnf or wherever my.cnf is located:

[mysqld]
max_connect_errors
variable

and

wait_timeout var. Some reasonable variable size would be:

max_connect_errors = 100000
wait_timeout = 60

If such (anyways) high values is still not high enough you can raise mysql config connection timeout

 

to

max_connect_errors = 100000000

Also if you want to try raise max_connect_errors var without making it permanenty (i.e. remember var setting after MySQL service restart), set it from MySQL cli with:

SET GLOBAL max_connect_errors


If you want to keep the set default max_connection_errors and fix it temporary, you can try to follow the error

Host '' is blocked because of many connection errors; unblock with 'mysqladmin flush-hosts'

suggestion and issue in root console:

mysqladmin flush-hosts

Same could also be done from MySQL Cli with cmd:
 

FLUSH HOSTS;

Allowing MySQL users access from all hosts – Fixing mysql ERROR 1045 (28000): Access denied for user ‘root’@’remote-admin.com’ (using password: YES)

Friday, June 20th, 2014

mysql_allow_access-from-remote-any-host-fix-access-error-after-sql-migration

I recently migrated MySQL database server from host A to host B (remotesystemadministration.com), because I wanted to have the mysql database server on a separate machine (have separation of server running services and have a dedicated mysql server).

MySQL server host (running on localhost previously was set from my mysql config my.cnf to listen and serve connections on localhost with

bind-address = 127.0.0.1

). MySQL is used by a Tomcat running Java application on localhost and my task was to set the Tomcat to use the MySQL database remotely to MySQL host B (new remote hostname where MySQL is moved is  remotesystemadminsitration.com and is running on IP 83.228.93.76).

Migration from MySQL Db server 1 (host A) to MySQL Db server 2 (host B) is done by binary copying the mysql database directory which in this case is (as it is a Debian server installed MySQL), the standard directory where mysql stores its database data is /var/lib/mysql ( datadir = /var/lib/mysql in /etc/mysql/my.cnf)

Binary copying of data from MySQL db (host A) to MySQL Db (host B) is done with rsync

After migrating and trying to login on migrated mysql  database on remotesystemadministration.net with mysql cli client:

remotesysadmin:~$ mysql -u root -p

I got following error:
 

ERROR 1045 (28000): Access denied for user 'root'@'remotesystemadministration.com' (using password: YES)


To fix the issue I had to login remotely from old migration server mysql (host A) cli:

mysql:~$ mysql -u root -p -h remotesystemadministration.com

and  run SQL commands:

GRANT ALL PRIVILEGES ON *.* TO 'root'@'remotesystemadministration.com' WITH GRANT OPTION;
GRANT USAGE ON *.* TO 'root'@'remotesystemadministration.com' IDENTIFIED BY 'secret-mysql-pass';
FLUSH PRIVILEGES;

Query OK, 0 rows affected (0.03 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)


Another way to solve the problem is to add the root user to be able to connect from any host (Enable MySQL root access from all host), to do so issue:

GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY 'password';
FLUSH PRIVILEGES;

Note: In newer version of MySQL, flush privileges could be omitted.

Another approach if you want to substitute access from localhost for all users and enable all users to be able to authenticate to mysql remotely is to execute SQL Query:

UPDATE USER SET host='%' WHERE host='localhost';

Allowing all users to be able to connect from anywhere on the internet is a very bad security practice anyways, if you already have a tight firewall setup and you can only access the server via specific remote IP addresses allowing MySQL access from all hosts / ips should be ok.

Play Dune2 on Debian Linux with dosbox – Dune 2 Mother of all Real Time Strategy games

Saturday, March 1st, 2014

medium_1809-dune-ii-the-building-of-a-dynasty_one_of_best_games_ever_linux_windows.gif

Dune II: The Building of a Dynasty (known also as Dune II: Battle for Arrakis in Europe is a game that my generation will never forget. Dune 2 is the "first" computer Real Time Strategy (RTE) game of the genre of the Warcraft I and Warcraft II / III and later Command and Conquer – Red Aleart, Age of Empires I / II and Starcraft …

dune2-unit-destroyed

I've grown up with Dune2 and the little computer geek community in my school was absolutely crazy about playing it. Though not historically being the first Real Time Strategy game, this Lucas Inc. 
game give standards that for the whole RTE genre for years and will stay in history of Computer Games as one of best games of all times.

I've spend big part of my teenager years with my best friends playing Dune2 and the possibility nowadays to resurrect the memories of these young careless years is a blessing.  Younger computer enthusiasts and gamers probably never heard of Dune 2 and this is why I decided to place a little post here about this legendary game.

dune-2-tank-vehicle - one of best games computer games ever

Its worthy out of curiosity or for fun to play Dune 2 on modern OS be it Windows or Linux. Since Dune is DOS game, it is necessary to play it via DOS emulator i.e. – (DosBox). 
Here is how I run dune2 on my Debian Linux:

1. Install dosbox DOS emulator

apt-get install --yes dosbox

2. Download Dune2 game executable

You can download my mirror of dune2 here

Note that you will need unzip to uanrchive it, if you don't have it installed do so:

apt-get install --yes unzip

cd ~/Downloads/
wget http://www.pc-freak.net/files/dune-2.zip

3.  Unzip archive and create directory to mount it emulating 'C:\' drive

mkdir -p ~/.dos/Dune2
cd ~/.dos/Dune2

unzip ~/Downloads/dune-2.zip
 

4. Start dosbox and create permanent config for C: drive auto mount


dosbox

To make C:\ virtual drive automatically mounted you have to write a dosbox config from inside dbox console

config -writeconf /home/hipo/.dosbox.conf

My home dir is in /home/hipo, change this with your username /home/username

Then exit dosbox console with 'exit' command

To make dune2 game automatically mapped on Virtual C: drive:

echo "mount c /home/hipo/.dos" >> ~/.dosbox.conf

Further to make dosbox start each time with ~/.dosbox.conf add alias to your ~/.bashrc 

vim ~/.bashrc
echo "alias dosbox='dosbox -conf /home/hipo/.dosbox.conf'" >> ~/.bashrc
source ~/.bashrc

Then to run DUNE2 launch dosbox:

dosbox

and inside console type:

c:
cd Dune2
Dune2.exe

dune2-first-real-time-strategy-game-harkonen-screenshot

For the lazy ones who would like to test dune you can play dune 2 online on this website

Useful VIM editor tip colorscheme evening – make your configurations look brighter in VI

Monday, February 24th, 2014

I just learned about cool VIM option from a collegue:

:colorscheme evening

What it does it makes configurations in vim edit look brighter like you seen in below screenshots.

– Before :colorscheme evening vim command

colorscheme_vim-linux-editor-options-screenshot

– After :colorscheme evening

colorscheme2_vim-linux-editor-options-screenshot

The option is really useful as often editing a config in vim on a random server is too dark and in order to read the config you have to strain your eyes in long term leading to eye damage.

Any other useful vim options, you use daily?

phpMyAdmin No activity within 1440 seconds; please log in again Fix

Friday, July 5th, 2013

phpmyadmin no activity within 1440 seconds please log in again screenshot Debian Gnu Linux
I had some complains from Web Developers who constantly was working on a Testing Web Development server. That their opened PhpMyadmin in browser is often closing opened session (auto logging out) with an error:
 

No activity within 1440 seconds; please log in again

This message was driving crazy people, as often they code something in PHP and design a new table or something and refreshing in browser blocked their work flow process with this annoying error …

Thanksfully there is an easy fix to that, just raise the time limit via /etc/phpmyadmin/config.inc.php

First its necessary to enable cookies authentication (by default it is commented):

Line:

//$cfg['Servers'][$i]['auth_type'] = 'cookie';

should be:

$cfg['Servers'][$i]['auth_type'] = 'cookie';

PHPMyAdmin 1140 seconds (24 minutes) timeout behavior behavior is controlled through variable: cfg['LoginCookieValidity']
Also it is necessary to increase timeout from server php.ini  (in Debian and Ubuntu via /etc/php5/apache2/php.ini or in CentOS / RHEL / Fedora Linux by editting /etc/php.ini and changing 1h session expiry setting:

session.gc_maxlifetime = 3600

to

(60*60*8  = 28800 – 8 hrs)

session.gc_maxlifetime = 28800

By default cfg['LoginCookieValidity'] is omitted from config.inc.php so you have to insert it at end of file.

A reasonable timeout value is 8 hours. To change PhPMyadmin Login TimeOut to 8 hours:

$cfg['LoginCookieValidity'] = 60 * 60 * 8; // in seconds (8 hours)

If you want to make Timeout Expire almost never (and you don't care about security) set it to some extra high timeout like 1 year  🙂

$cfg['LoginCookieValidity'] = 3600 * 24 * 365; // 1 year
 

Fixing common WordPress empty page error

Thursday, May 2nd, 2013

A very common error for  wordpress based blog / site  whenever you modified
something inside pluginsis to receive empty page screen on user visit.

This error often is because of any installed WordPress caching plugins like
WP SUPER CACHE

or

W3 TOTAL CACHE.

One way to solve it is to delete from wp-config/plugins/ Folder whatever plugin is
causing the troubles.

If this doesn't fix the error and you need to Debug what is causing the odd
Empty pages.
Open wp-config.php and somewhere near beginning of file include:
 

error_reporting(E_ALL); ini_set('display_errors', 1);
define( 'WP_DEBUG', true);

After saving wp-config.php and refreshing WP size in Browser
(after cleaning browser cache)

if you get an error like:

Fatal error: Allowed memory size of 8388608 bytes exhausted
(tried to allocate 252212 bytes) in
/var/www/blog/wp-includes/cache.php on line 4


This is due to set maximum System Wide memory Limit of PHP Scripts to 8MB.
To solve that raise the PHP Limit to lets say 64M from wp-config.php by adding
in it line:

define('WP_MEMORY_LIMIT', '64M');

That's all WordPress should be working normal again.

Enjoy 🙂