Posts Tagged ‘grep’

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Testing your local network for open Windows shares from Linux router

Friday, June 28th, 2013

Windows sharing testing local network for open shared directories Samba Software logo

Whether you administrate local Windows network behind a DMZ router, It is useful to routinely scan from Linux router which Windows hosts on the network has enabled sharing? The reason is some Windows user might share something by mistake which is not supposed to be shared without even he realizes this.
 

 In case, where new Linux router is configured and Windows hosts behind it can't locate each other on network make sure you have in your firewall before any filtering (REJECT / DROP) firewall rules:

iptables -A INPUT -s 192.168.5.1/24 -m state --state NEW -p tcp --dport 137 -j ACCEPT
iptables -A INPUT  -s 192.168.5.1/24 -m state --state NEW -p tcp --dport 138 -j ACCEPT
iptables -A INPUT  -s 192.168.5.1/24 -m state --state NEW -p tcp --dport 139 -j ACCEPT
iptables -A INPUT  -s 192.168.5.1/24 -m state --state NEW -p tcp --dport 445 -j ACCEPT

iptables -A INPUT -s 0.0.0.0/24 -m state --state NEW -p tcp --dport 445 -j REJECT
iptables -A INPUT -s 0.0.0.0/24 -m state --state NEW -p tcp --dport 138 -j REJECT
iptables -A INPUT -s 0.0.0.0/24 -m state --state NEW -p tcp --dport 139 -j REJECT
iptables -A INPUT -s 0.0.0.0/24 -m state --state NEW -p tcp --dport 137 -j REJECT
(Qquickest way to place rules to exec on next boot is via /etc/rc.local)

Once set, to check all is fine with fwall rules:

router:~# iptables -L INPUT -n

Chain INPUT (policy ACCEPT)

target     prot opt source               destination         

ACCEPT     tcp  —  192.168.5.0/24       0.0.0.0/0           state NEW tcp dpt:137
ACCEPT     tcp  —  192.168.5.0/24       0.0.0.0/0           state NEW tcp dpt:138
ACCEPT     tcp  —  192.168.5.0/24       0.0.0.0/0           state NEW tcp dpt:139
ACCEPT     tcp  —  192.168.5.0/24       0.0.0.0/0           state NEW tcp dpt:445 
REJECT tcp — 0.0.0.0/24 0.0.0.0/0 state NEW tcp dpt:445 reject-with icmp-port-unreachable
REJECT tcp — 0.0.0.0/24 0.0.0.0/0 state NEW tcp dpt:138 reject-with icmp-port-unreachable
REJECT tcp — 0.0.0.0/24 0.0.0.0/0 state NEW tcp dpt:139 reject-with icmp-port-unreachable
REJECT tcp — 0.0.0.0/24 0.0.0.0/0 state NEW tcp dpt:137 reject-with icmp-port-unreachable

On CentOS / Fedora / Redhat router place below rules in /etc/sysconfig/iptables – default firewall configuration file for RPM based distros:

-A RH-Firewall-1-INPUT -s 192.168.1.0/24 -m state --state NEW -p tcp --dport 137 -j ACCEPT
-A RH-Firewall-1-INPUT -s 192.168.1.0/24 -m state --state NEW -p tcp --dport 138 -j ACCEPT
-A RH-Firewall-1-INPUT -s 192.168.1.0/24 -m state --state NEW -p tcp --dport 139 -j ACCEPT
-A RH-Firewall-1-INPUT -s 192.168.1.0/24 -m state --state NEW -p tcp --dport 445 -j ACCEPT
 -A RH-Firewall-1-INPUT -s 0.0.0.0/24 -m state --state NEW -p tcp --dport 137 -j REJECT
 -A RH-Firewall-1-INPUT -s 0.0.0.0/24 -m state --state NEW -p tcp --dport 138 -j REJECT
 -A RH-Firewall-1-INPUT -s 0.0.0.0/24 -m state --state NEW -p tcp --dport 139 -j REJECT
 -A RH-Firewall-1-INPUT -s 0.0.0.0/24 -m state --state NEW -p tcp --dport 445 -j REJECT

After that check lets say 192.168.5.0/24 whether Windows Samba shares ports are reachable:

 To check hosts with Sharing easiest way is to scan your network C class range with nmap for all ports through which Windows Samba shares communicate – i.e. check for open state TCP / UDP port numbers 139,137,139,445 list of samba used default ports is in  /etc/services

router:~# grep netbios /etc/services

netbios-ns 137/tcp # NETBIOS Name Service
netbios-ns 137/udp
netbios-dgm 138/tcp # NETBIOS Datagram Service
netbios-dgm 138/udp
netbios-ssn 139/tcp # NETBIOS session service
netbios-ssn 139/udp

Note that Port 445 microsoft-ds is not in /etc/services because it is not common used (only used whether Windows hosts are using Active Directory)

 
router:~# nmap 192.168.5.1-255 -p 139,137,139,445

Interesting ports on 192.168.5.23:

PORT    STATE    SERVICE
137/tcp filtered netbios-ns
139/tcp open     netbios-ssn
445/tcp open     microsoft-ds
MAC Address: 00:AA:4D:2F:4D:A2 (Giga-byte Technology Co.)


Interesting ports on 192.168.5.31:

PORT    STATE    SERVICE
137/tcp filtered netbios-ns
139/tcp open     netbios-ssn
445/tcp open     microsoft-ds
MAC Address: 3C:B9:2B:76:A6:08 (Unknown)
….
…..

 

 

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Posted in Computer Security, Linux, System Administration, Various | No Comments »

Linux: Delete empty lines from text file with sed, awk, grep and vim

Saturday, March 23rd, 2013

As a system administrator, sometimes is necessary to do basic plain text processing for various sysadmin tasks. One very common task I do to remove empty lines in file. There are plenty of ways to do it i.e. – with grep, sed, awk, bash, perl etc.

1. Deleting empty file lines with sed

The most standard way to do it is with sed, as sed was written to do in shell quick regexp. Here is how;

sed '/^\s*$/d' file_with_empty_lines.txt > output_no_empty_lines.txt
2. Deleting empty file lines with awk

It is less of writting with awk, but I always forget the syntax and thus I like more sed, anyways here is how with awk;

cat file_with_empty_lines.txt | awk 'NF' >
output_no_empty_lines.txt

3. Deleting empty lines with grep

Grep  regular expression can be used. Here is grep cmd to cut off empty lines from file;

grep -v '^\s*$' file_with_empty_lines.txt >
output_no_empty_lines.txt

4. Delete empty files with vi / vim text editor
Open vi / vim text editor

$ vim

Press Esc+: and if empty lines doesn't have empty space characters use command

g/^$/d

Whether, empty lines contain " " – space characters (which are not visible in most text editors), use vi cmd:
g/^ $/d

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Posted in Linux, Programming, System Administration, Various | No Comments »

Enable Apache libphp extension to interpret PHP scripts on FreeBSD 9.1

Saturday, January 12th, 2013

Enable php scripts to be interpreted / executed by PHP on freebsd
First you have to have installed and properly set up Apache from port, in my case this is Apache:

 

freebsd# pkg_info | grep -i apache
ap22-mod_fastcgi-2.4.6_3 A fast-cgi module for Apache
apache22-2.2.23_4   Version 2.2.x of Apache web server with prefork MPM.
apr-1.4.6.1.4.1_3   Apache Portability Library
I've installed it from source port /usr/ports/www/apache22, with:

freebsd# cd /usr/ports/www/apache22;
freebsd# make install clean
.....
 Then to be able to start Apache from init script and make it run automatically on FBSD system reboot:

 

echo 'apache22_enable="YES"' >> /etc/rc.conf
I've also installed php5-extensions port;

freebsd# cd /usr/ports/lang/php5-extensions/
freebsd# make install clean
....
freebsd# cp -rpf /usr/local/etc/php.ini-production /usr/local/etc/php.ini
I had to select the exact Apache PHP library extensions I need, after selecting and installing, here is the list of PHP extensions installed on system:

freebsd# pkg_info | grep -i php5
php5-5.4.10         PHP Scripting Language
php5-bz2-5.4.10     The bz2 shared extension for php
php5-ctype-5.4.10   The ctype shared extension for php
php5-dom-5.4.10     The dom shared extension for php
php5-filter-5.4.10  The filter shared extension for php
php5-gd-5.4.10      The gd shared extension for php
php5-gettext-5.4.10 The gettext shared extension for php
php5-hash-5.4.10    The hash shared extension for php
php5-iconv-5.4.10   The iconv shared extension for php
php5-json-5.4.10    The json shared extension for php
php5-mbstring-5.4.10 The mbstring shared extension for php
php5-mcrypt-5.4.10  The mcrypt shared extension for php
php5-mysql-5.4.10   The mysql shared extension for php
php5-pdo-5.4.10     The pdo shared extension for php
php5-pdo_sqlite-5.4.10 The pdo_sqlite shared extension for php
php5-phar-5.4.10    The phar shared extension for php
php5-posix-5.4.10   The posix shared extension for php
php5-session-5.4.10 The session shared extension for php
php5-simplexml-5.4.10 The simplexml shared extension for php
php5-sqlite3-5.4.10 The sqlite3 shared extension for php
php5-tokenizer-5.4.10 The tokenizer shared extension for php
php5-xml-5.4.10     The xml shared extension for php
php5-xmlreader-5.4.10 The xmlreader shared extension for php
php5-xmlwriter-5.4.10 The xmlwriter shared extension for php
php5-zip-5.4.10     The zip shared extension for php
php5-zlib-5.4.10    The zlib shared extension for php
By default DirectoryIndex is not set to process index.php and .php, file extensions will not be interpreted by libphp, instead requests to .php, just opens them as plain text files.

In Apache config httpd.conf, libphp5 module should be displaying as loaded, like so:

freebsd# grep -i php5 /usr/local/etc/apache22/httpd.conf
LoadModule php5_module        libexec/apache22/libphp5.so

Next step find in /usr/local/etc/apache22/httpd.conf lines:

<IfModule dir_module>
DirectoryIndex index.html

Change

DirectoryIndex index.html

to

DirectoryIndex index.php index.html

(If you would like index.php to be processed as primary whether an Apache directory contains both .php and .html files.

After DirectoryIndex index.php, paste following;

<IfModule mod_dir.c>
    <IfModule mod_php3.c>
        <IfModule mod_php5.c>
            DirectoryIndex index.php index.php3 index.html
        </IfModule>
        <IfModule !mod_php4.c>
            DirectoryIndex index.php3 index.html
        </IfModule>
    </IfModule>
    <IfModule !mod_php3.c>
        <IfModule mod_php5.c>
            DirectoryIndex index.php index.html index.htm
        </IfModule>
        <IfModule !mod_php4.c>
            DirectoryIndex index.html
        </IfModule>
    </IfModule>
</IfModule>

Open /usr/local/etc/apache22/httpd.conf. I use vim so:

vim /usr/local/etc/apache22/httpd.conf

and press CTRL+g to go to last line of file. Last line is:

Include etc/apache22/Includes/*.conf

I press I to insert text and paste before the line:

AddType application/x-httpd-php .php
AddType application/x-httpd-php-source .phpS
AddType application/x-httpd-php .php .htm .html

And save with the usual vim esc+ :x! (exit, save and overwrite changes command).

Then restart Apache to load new settings, after testing Apache config is okay;

freebsd# apache2ctl -t
Syntax OK
freebsd# /usr/local/sbin/apachectl -k restart
To test php conduct the usual test if php is interpretting code with phpinfo(); by creating  file php_info.php and pasting inside:

<?php
phpinfo();
?>
One important note, to make here is if you try to use phpinfo(); test code like:

<?
phpinfo();
?>

You will get in your browser empty pages content – which usually appear only, if PHP execution fails. Even if you try to enable PHP errors to be displayed in browser by setting

display_errors = On in /usr/local/etc/php.ini, or configuring a separate php error_log file with setting variable error_log, i.e.:

error_log = /var/log/php_error.log
No error or warning is to be both displayed in browser or recorded in log. After consulting in irc.freenode.net #php, I was pointed out by nezZario that this unusual behavior is normal for PHP 5.4, as well as explained this behavior is controlled by var called:

Short Open Tags

To enable Short Open Tags to interpret PHP code inside <? set in /usr/local/etc/php.ini

short_open_tag = On

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Posted in FreeBSD, System Administration, Web and CMS | No Comments »

Editting binary files in console and GUI on FreeBSD and Linux

Thursday, April 26th, 2012

I’ve recently wanted to edit one binary file because there was compiled in the binary a text string with a word I didn’t liked and therefore I wanted to delete. I know I can dig in the source of the proggie with grep and directly substitute my “unwatned text” there but I wanted to experiment, and see what kind of hex binary text editors are for Free OSes.
All those who lived the DOS OS computer era should certainly remember the DOS hex editors was very enjoyable. It was not rare case, where in this good old days, one could simply use the hex editor to “hack” the game and add extra player lives or modify some vital game parameter like put himself first in the top scores list. I even remember some DOS programs and games was possible to be cracked with a text editor … Well it was times, now back to current situation as a Free Software user for the last 12 years it was interesting to see what is the DOS hexeditor like alternatives for FreeBSD and Linux and hence in this article I will present my findings:

A quick search in FreeBSD ports tree and Debian installable packages list, I’ve found a number of programs allowing one to edit in console and GUI binary files.

Here is a list of the hex editors I will in short review in this article:

  • hexedit
  • dhex
  • chexedit
  • hte
  • hexer
  • hexcurse
  • ghex
  • shed
  • okteta
  • bless
  • lfhex

1. hexedit on Linux and BSD – basic hex editor

I’ve used hexedit already on Linux so I’ve used it some long time ago.

My previou experience in using hexedit is not too pinky, I found it difficult to use on Redhat and Debian Linux back in the day. hexedit is definitely not a choice of people who are not “initiated” with hex editting.
Anyways if you want to give it a try you can install it on FreeBSD with:

freebsd# cd /usr/ports/editors/hexedit
freebsd# make install clean
…

On Debian the hexedit, install package is named the same so installation is with apt:

debian:~# apt-get –yes install hexedit

hexedit screenshot Debian Linux Squeeze

2. Hex editting with chexedit

I’ve installed chexedit the usual way from ports:

freebsd# cd /usr/ports/editors/chexedit
freebsd# make install clean

…

chexedit is using the ncurses text console library, so the interface is very similar to midnight commander (mc) as you see from below’s screenshot:

Chexeditor FreeBSD 7.2 OS Screenshot

Editting the binary compiled in string was an easy task with chexedit as most of the commands are clearly visible, anyways changing a certain text string contained within the binary file with some other is not easy with chexedit as you need to know the corresponding binary binary value representing each text string character.
I’m not a low level programmer, so I don’t know the binary values of each keyboard character and hence my competence came to the point where I can substitute the text string I wanted with some unreadable characters by simply filling all my text string with AA AA AA AA values…

chexedit on Debian is packaged under a deb ncurses-hexedit. Hence to install it on Deb run:

debian:~# apt-get –yes install ncurses-hexedit
…

Further on the binary to run chexedit on binary contained within ncurses-hexedit is:

debian:~# hexeeditor

3. Hex Editting on BSD and Linux with hte

Just after trying out chexedit, I’ve found about the existence of one even more sophisticated hexeditor console program available across both FreeBSD and Linux.
The program is called hte (sounds to me a bit like the Indian word for Elephant “Hatti” :))

hte is installable on Debian with cmd:

debian:~# apt-get install ht

On FreeBSD the port name is identical, so to install it I execed:

freebsd# cd /usr/ports/editors/hte
freebsd# make install clean
…

hte is started on Debian Linux (and presumably other Linux distros) with:

$ hte

On FreeBSD you need to run it with ht command:

freebsd# ht

You see how hte looks like in below screenshot:

ht has the look & feel like midnight commander and I found it easier to use than chexedit and hexeditor
4. hexer VI like interface for Linux

As I was looking through the available packages ready to install, I’ve tried hexer

debian:~# apt-get install –yes hexer
…

hexer does follow the same standard commands like VIM, e.g. i for insert, a for append etc.

Hexer Debian Linux vim like binary editor screenshot

It was interesting to find out hexer was written by a Bulgarian fellow Petar Penchev 🙂
(Proud to be Bulgarian)

http://people.freebsd.org/~roam/ – Petar Penchev has his own page on FreeBSD.org

As a vim user I really liked the idea, the only thing I didn’t liked is there is no easy way to just substitute a string within the binary with another string.

5. hexcurse another ncurses library based hex editor

On Deb install and run via:

debian:~# apt-get –yes install hexcurse
debian:~# hexcurse /usr/bin/mc

Hexcurse Debian Linux text binary editor screenshot

hexcurse is also available on FreeBSD to install it use cmd:

freebsd# cd /usr/ports/editors/hexcurse
freebsd# make install clean
….

To access the editor functions press CTRL+the first letter of the word in the bottom menu, CTRL+H, CTRL+S etc.
Something I disliked about it is the program search is always in hex, so I cannot look for a text string within the binaries with it.

6. ghex – Editting binary files in graphical environment

If you’re running a graphical environment, take a look at ghex. ghex is a gnome (graphical hex) editor.Installing ghex on Debian is with:

debian:~# apt-get –yes install ghex
….

To run ghex from terminal type:

debian:~# ghex2

GHex2 GNOME hex binary editor screenshot

To install ghex on FreeBSD (and I assume other BSDs), install via port:

freebsd# cd /usr/ports/editors/ghex
freebsd# make install clean

Gnome hex editor have plenty of tools, useful for developers to debug binary files.

Some nice tools one can find are under the the menus:

Windows -> Character Table

This will show a complete list of each keyboard sent character in ASCII, Hex, Decimal, Octal and Binary

Screenshot ghex Character table Debian Linux

Another useful embedded tool in ghex is:

Windows -> Type Convertion Dialog

Ghex type convertion dialog screenshot

Note that if you want to use the Type Convertion Dialog tool to find the representing binary values of a text string you will have to type in the letters one by one and save the output within a text file and later you can go and use the same editor to edit the text string within the binary file you like.

I’m not a programmer but surely for programmers or people who want to learn some binary counting, this 2 ghex edmebbed tools are surely valuable.

To conclude even though there are plenty of softwares for hex editting in Linux and BSD, none of them is not so easy to use as the old DOS hexdedit tool, maybe it will be a nice idea if someone actually rewrites the DOS tool and they package it for various free operating systems, I’m sure many people will find it helpful to have a 1:1 equivalent to the DOS tool.

7. Shed pico like interfaced hex editor

For people, who use pico / nano as a default text editor in Linux shed will probably be the editor of choice as it follows the command shortcuts of picoOn Deb based distros to install it run:

debian:~# apt-get install –yes shed
…

shed pico like hex binary editor Linux

Shed has no BSD port as of time of writting.8. Okteta a KDE GUI hex editor

For KDE users, I found a program called okteta. It is available for Deb based Linuxes as deb to install it:

debian:~# apt-get –yes install okteta

Screenshot Okteta Debian GNU / Linux Squeeze

As of time of writting this article there is no okteta port for BSDs.
Okteta has plenty of functions and even has more of a functions than ghexedit. Something distinctive for it is it supports opening multiple files in tabs.

9. lfhex a large file text editor

lfhex is said to be a large (binary) file text editor, I have not tested it myself but just run it to see how it looks like. I don’t have a need to edit large binary files too, but I guess there are people with such requirements too 🙂

lfhex - Linux The Large file hex editor

To install lfhex on Debian:

debian:~# apt-get install –yes lfhex

lfhex has also a FreeBSD port installable via:

freebsd# cd /usr/ports/editors/lfhex
freebsd# make install clean

10. Bless a GUI tool for editting large hex (binary) files

Here is the description directly taken from the BSD port /usr/ports/editors/bless

Bless is a binary (hex) editor, a program that enables you to edit files asa sequence of bytes. It is written in C# and uses the Gtk# bindings for theGTK+ toolkit.

To install and use ot on deb based Linuxes:

debian:~# apt-get install –yes bless
….

On BSD installation is again from port:

freebsd# cd /usr/ports/editors/bless
freebsd# make install clean
….

Something that makes bless, maybe more desirable choice for GUI users than ghex is its availability of tabs. Opening multiple binaries in tabs will be useful only to few heavy debuggers.

Bless GUI hex editor Debian Linux tabs opened screenshot

11. Ghextris – an ultra hard hacker tetris game 🙂

For absolute, hacker / (geeks), there is a tetris game called ghextris. The game is the hardest tetris game I ever played in my life. It requires more than regular IQ and a lot of practice if you want to become really good in this game.

To enjoy it:

debian:~# apt-get –yes install ghextris

Ultra hrad hardcore hackers game ghextris screenshot

Unfortunately there is no native port of ghextris for BSD (yet). Anyhow, it can be probably run using the Linux emulation or even compiled from source.
Well that’s all I found for hexedit-ing, I’ll be happy to hear if someone can give me some feedback on his favourite editor.

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Posted in System Administration | 4 Comments »

Fix Null error in WordPress comment reply with wordpress-threaded-comments plugin enabled

Friday, April 6th, 2012

I'm running WordPress for already 3 years or so now. Since some very long time. The first wordpress install, I can hardly remember but it something like wordpress 2.5 or wordpress 2.4

Since quite a long time my wordpress blog is powered by a number of plugins, which I regularly update, whenever new plugins pops up …
I haven't noticed most of the time problems during major WordPress platform updates or the update of the installed extensions. However, today while I tried to reply back to one of my blog comments, I've been shocked that, I couldn't.
Pointing at the the Comment Reply box and typing inside was impossible and a null message was stayed filled in the form:

To catch what was causing this weird misbehaving with the reply comments functionality, I grepped through my /var/www/blog/wp-content/plugins/* for the movecfm(null,0,1,null):

# cd /var/www/blog/wp-content/plugins
# grep -rli 'movecfm(null,0,1,null)' */*.php
wordpress-thread-comment/wp-thread-comment.php

I've taken the string movecfm(null,0,1,null) from the browser page source in in my Firefox by pressing – Ctrl+U).

Once I knew of the problem, I first tried commenting the occurances of the null fields in wp-thread-comment.php, but as there, were other troubles in commenting this and I was lazy to read the whole code, checked online if some other fellows experienced the same shitty null void javascript error and already someone pointed at a solution. In the few minutes search I was unable to find anyone who reported for this bug, but what I found is some user threads on wordpress.org mentioning since WordPress 2.7+ the wordpress-threaded-comments is obsolete and the functionality provided by the plugin is already provided by default in newer WPinstalls.

Hence in order to enable the threaded comments WordPress (embedded) reply functionality from within the wp-admin panel used:

Settings -> Discussions -> Enable Threaded (nested) comments (Tick)

Enable Nested Comments WordPress default wp comments enable reply functionality screenshot

You see there is also an option to define how many nested comments subcomments, can be placed per comment, the default was 5, but I thought 5 is a bit low so increased it to 10 comments reply possible per comment.

Finally, to prevent the default threaded comments to interfere with the WordPress Threaded Comments plugin, disabled the plugin through menus:

Plugins -> Active -> WordPress Thread Comments (Deactivate)

This solved the weird javascript null "bug" caused by wordpress-threaded-comments once and for all.
Hopefully onwards, my blog readers will not have issues with threaded Reply Comments.

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Posted in Web and CMS, Wordpress | 1 Comment »

Check and Restart Apache if it is malfunctioning (not returning HTML content) shell script

Monday, March 19th, 2012

Check and Restart Apache Webserver on Malfunction, Apache feather logo

One of the company Debian Lenny 5.0 Webservers, where I'm working as sys admin sometimes stops to properly server HTTP requests.
Whenever this oddity happens, the Apache server seems to be running okay but it is not failing to return requested content

I can see the webserver listens on port 80 and establishing connections to remote hosts – the apache processes show normally as I can see in netstat …:

apache:~# netstat -enp 80
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address Foreign Address State User Inode PID/Program name
tcp 0 0 xxx.xxx.xxx.xx:80 46.253.9.36:5665 SYN_RECV 0 0 -
tcp 0 0 xxx.xxx.xxx.xx:80 78.157.26.24:5933 SYN_RECV 0 0 -
...

Also the apache forked child processes show normally in process list:

apache:~# ps axuwwf|grep -i apache
root 46748 0.0 0.0 112300 872 pts/1 S+ 18:07 0:00 \_ grep -i apache
root 42530 0.0 0.1 217392 6636 ? Ss Mar14 0:39 /usr/sbin/apache2 -k start
www-data 42535 0.0 0.0 147876 1488 ? S Mar14 0:01 \_ /usr/sbin/apache2 -k start
root 28747 0.0 0.1 218180 4792 ? Sl Mar14 0:00 \_ /usr/sbin/apache2 -k start
www-data 31787 0.0 0.1 219156 5832 ? S Mar14 0:00 | \_ /usr/sbin/apache2 -k start

In spite of that, in any client browser to any of the Apache (Virtual hosts) websites, there is no HTML content returned…
This weird problem continues until the Apache webserver is retarted.
Once webserver is restarted everything is back to normal.
I use Apache Check Apache shell script set on few remote hosts to regularly check with nmap if port 80 (www) of my server is open and responding, anyways this script just checks if the open and reachable and thus using it was unable to detect Apache wasn't able to return back HTML content.
To work around the malfunctions I wrote tiny script – retart_apache_if_empty_content_is_returned.sh

The scripts idea is very simple;
A request is made a remote defined host with lynx text browser, then the output of lines is counted, if the output returned by lynx -dump http://someurl.com is less than the number returned whether normally invoked, then the script triggers an apache init script restart.

I've set the script to periodically run in a cron job, every 5 minutes each hour.
# check if apache returns empty content with lynx and if yes restart and log it
*/5 * * * * /usr/sbin/restart_apache_if_empty_content.sh >/dev/null 2>&1

This is not perfect as sometimes still, there will be few minutes downtime, but at least the downside will not be few hours until I am informed ssh to the server and restart Apache manually …

A quick way to download and set from cron execution my script every 5 minutes use:

apache:~# cd /usr/sbin
apache:/usr/sbin# wget -q https://www.pc-freak.net/bscscr/restart_apache_if_empty_content.sh
apache:/usr/sbin# chmod +x restart_apache_if_empty_content.sh
apache:/usr/sbin# crontab -l > /tmp/file; echo '*/5 * * * *' /usr/sbin/restart_apache_if_empty_content.sh 2>&1 >/dev/null
 

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Posted in System Administration, Web and CMS | 7 Comments »

How to change from default main menu text to another text in Joomla

Tuesday, December 21st, 2010

To change the Main Menu link menu entry in Joomla, from Joomla administ rator I tried to:

Menus -> Main Menu -> Menus

I’ve changed the title but the change didn’t appeared in my Joomla based website .

I tried to change it directly in the source code of the website by looking for ‘Main Menu’ string with:

debian:/home/mysite/www# grep -rli 'Main Menu' *

but it appeared too complicated and after trying few string changes in few files I decided to drop this kind of approach.

A bit of investigation online led me to how to achieve what I was trying to dire ctly from Joomla.

Here is how. In Joomla administrator move to:

Extensions -> Module Manager

In the list you will the Module Manager appear under the list Module Name , therein you have to click over Main Menu text and change it to whatever you like to.

The new text you entered will appear on the joomla website immediately, enjoy.

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Posted in Joomla, Linux, SEO | 2 Comments »

How to install Samsung ML-2010 (ML-2010P) Mono Laser Printer on Xubuntu GNU/Linux

Wednesday, January 18th, 2012

I had to make one old Samsung ML-2010P Laser Printer work on Xubuntu Linux . I've had some issues in installing it, I couldn't fine any step by step tutorial online, on how the printer can be made work fine on Linux. Therefore I took the time to experiment and see if I could make it work. Since the printer is old, not much people are interested any more in making the printer operational on Linux, hence I couldn't find too much relevant posts and sites on the net, anyways thanks God after a bit of pondering I finally succeeded to make the Samsung ML-2010P printer to print on Linux.This are the exact steps one has to follow to make this old bunch of hardware to play nice on Linux:

1. use lsusb to list the printer model

root@linux:~# lsusb |grep -i samsung
Bus 001 Device 003: ID 04e8:326c Samsung Electronics Co., Ltd ML-2010P Mono Laser Printer

You see the printer reports as Samsung Electronics Co., Ltd ML-2010P Mono Laser Printer

2. Install cups printing service required packages

root@linux:~# apt-get install cups cups-bsd cups-client cups-common
root@linux:~# apt-get install cups-driver-gutenprint ghostscript-cups
root@linux:~# apt-get install python-cups python-cupshelpers

3. Install foomatic packages

root@linux:~# apt-get install foomatic-db foomatic-db-engine foomatic-db-gutenprint
root@linux:~# apt-get install foomatic-filters python-foomatic

4. Install hpijs hplip printconfand other packages necesssery for proper printer operation

root@linux:~# apt-get install hpijs hplip hplip-data ijsgutenprint
root@linux:~# apt-get install min12xxw openprinting-pdds printconf foo2zjs

P.S. Some of the packages I list might already have been installed as a dependency to another package, as I'm writting this article few days after I've succeeded installing the printer, I don't remember the exact install order.

5. Install splix (SPL Driver for Unix)

Here is a quote taken from Spix's project website:

"SpliX is a set of CUPS printer drivers for SPL (Samsung Printer Language) printers.
If you have a such printer, you need to download and use SpliX. Moreover you will find documentation about this proprietary language.
"

root@linux:~# apt-get install splix

For more information on splix, check on Splix SPL driver for UNIX website http://splix.ap2c.org/

You can check on the projects website the Samsung ML 2010 Printer is marked as Working
Next step is to configure the Printer

6. Go to Cups interface on localhost in browser and Add the Samsung printer.

Use Firefox, SeaMonkey or any browser of choice to configure CUPS:

Type in the browser:

http://localhost:631

Next a password prompt will appear asking for a user/pass. The user/pass you have to use is the same as the password of the user account you're logged on with.

UNIX Linux Administration CUPS Printer adding Samsung ML 2010 ML-2010P Xubuntu

Click on the Add Printer button and choose to add the Samsung ML-2010.

Then restart the CUP Service (cupsd) to make it load the new settings:

root@linux:~# /etc/init.d/cups restart

Now give the printer a try in printing some page in SeaMonkey, Chrome or Firefox (the quickest way is through pressing CTRL + P )

Following this steps, I've managed to run the printer on Xubuntu Linux, though the same steps if followed should most probably make the Samsnung ML 2010 play nice with other Linux distributions with a little or no adjustments.
I'll be glad to hear if someone succeeded in making the printer work on other distributions, if so please drop me a comment.
That's all folks! Enjoy printing 😉

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Posted in Linux, System Administration, Web and CMS | 2 Comments »

Debian (Unstable) Squeeze / Sid /usr/lib32/alsa-lib/libasound_module_pcm_pulse.so linked to missing libraries

Thursday, September 10th, 2009

While playing with my installed programs on my recently updated Debian I stepped into a problem with /usr/lib32/alsa-lib/libasound_module_pcm_pulse.so. It seems the library was linked to two non-existing libraries: /emul/ia32-linux/lib/libwrap.so.0 as well as /emul/ia32-linux/usr/lib/libgdbm.so.3. A temporary solution to the issue is pointed out in Debian of the Debian Bug reports . As the report reads to solve that it’s required to:

1. Download libwrap0_7.6.q-18_i386.deb and libgdbm3_1.8.3-6+b1_i386.deb.

2. Extract the packages:dpkg -X libwrap0_7.6.q-18_i386.deb /emul/ia32-linux/dpkg -X libgdbm3_1.8.3-6+b1_i386.deb /emul/ia32-linux/

3. echo /emul/ia32-linux/lib >> /etc/ld.so.conf.d/ia32.conf

4. Execute /sbin/ldconfig

5. Check if all is properly linkedExecute ldd /usr/lib32/alsa-lib/libasound_module_pcm_pulse.so|grep -i “not found”Hopefully all should be fixed now.

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Posted in Linux and FreeBSD Desktop, Linux Audio & Video, Skype on Linux, System Administration | No Comments »

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