FreeBSD version 5.0/6.0 or later

Newer version of FreeBSD has special start, stop, restart script, you can use this script restart inetd:

#/etc/rc.d/inetd restart

Old method (works on all variant of UNIX/Linux/BSD oses)
Once you made changes to inetd (internet super-server)configuration file (/etc/inetd.conf) you can use kill or killall command as follows to restart inetd:

# killall -HUP inetd

OR

# kill -HUP inetd

OR

# kill -HUP `cat /var/run/inetd.pid`

This causes the inetd program to restart and examine its configuration files. This is especially useful if you have changed the configuration settings.

The core.xxx files are created on Linux servers and holds the current state of a process working memory when a process is crashed. To view the core.xx files in Linux, execute the command:

root@host [~]# strings core.xxx

It will list different state of a process on each line.

PHP Warning:  PHP Startup: Unable to load dynamic library ‘/usr/lib64/php/modules/ffmpeg.so’ – /usr/lib64/php/modules/ffmpeg.so:
undefined symbol: _php_create_ffmpeg_frame in Unknown on line 0

You may also notice the “PIX_FMT_RGBA32″ error message while compiling ffmpeg-php

ffmpeg-php-0.5.0/ffmpeg_frame.c:495: error: ‘PIX_FMT_RGBA32′ undeclared (first use in this function)

The above error messages is the result of incorrect function declared in the ffmpeg_frame.c file under the ffmpeg-php-0.x.0 directory.

Solution:

Goto the the ffmpeg-php-0.x.0 directory and edit the ffmpeg_frame.c file

vi ffmpeg-php-0.x.0/ffmpeg_frame.c

Now replace every instance of ‘PIX_FMT_RGBA32′ with ‘PIX_FMT_RGB32′ in the file by executing

:%s/PIX_FMT_RGBA32/PIX_FMT_RGB32

OR

replace “PIX_FMT_RGBA32″ “PIX_FMT_RGB32″ — ffmpeg_frame.c

Save the file and compile ‘ffmpeg-php’ again using the following steps

cd ffmpeg-php-0.x.0
make clean
./configure
make
make install

Once done, ffmpeg should work along with PHP now.

You might have a small office where you customise one desktop just how you like it and need to roll this out to N other PC’s or simply want a backup of a server or desktop to another machine or even to an image file.

The main tool here is netcat which is extremely powerful and has a multitude of other great uses that won’t be covered here.

Target Machine:

** Boot to linux rescue mode with networking (CentOS works fine)

Initiate netcat to listen on port 30 – # nc -l -p
| dd of=/dev/sda (assuming the hard drive is sda and not hda):

# nc -l -p 30 | dd of=/dev/sda

Source Machine:

Dump the contents of the disk to the target PC – #dd if=/dev/sda | nc

# dd if=/dev/sda | nc 192.168.0.20 30

Then to check that traffic is flowing, on the source go to another terminal (ALT/F2) and dump the tcp data on the NIC (assuming it’s eth0):

tcpdump -tnli eth0 port 30

If you just want a backup image you could change the above output on the taget to:

# nc -l -p 30 | dd of=mybackup.img

That’s it. Naturally the target PC/disk cannot be smaller than the source:) I hope this saves someone a lot of time.

Incoming search terms:

• centos nc and dd (1)

When you try and rename it the following is given:

$ mv ––index.html index.html.renamed
mv: unrecognized option `––index.html’
Try `mv ––help’ for more information.

I also tried delimiting it the normal way, but it wouldn’t work either:

    mv \–\–index.html index.html.renamed

The correct way to rename it is:

    mv ./––index.html index.html.renamed

Because –– has special meaning, you can’t delimit it with a simple backslash (\), you have to put a path reference in there to delimit it. So my path working directory (pwd) was /home/user/data/ where the file was located, so I could use ./ to reference the current pwd. The other option is to put the full path in:

    mv /home/user/data/––index.html index.html.renamed

Hopefully this helps out some other Linux server administrator out there who’s mind it has slipped.

Let’s not hesitate and look at few usage examples… Want to know what’s the latest version of a particular kernel-tree?

$ ketchup -s 2.6

    2.6.17.7

$ ketchup -s 2.6-mm

    2.6.18-rc1-mm2

Let’s play with your kernel sources a bit. First of all, you surely want to check what version you currently got lying around…

$ cd /usr/src/linux

$ ketchup -m

2.6.17.6

Let’s assume there is a newer kernel version available and you want to download it, bunzip it, revert the old patch and apply the new one. Nothing easier than that:

# cd /usr/src/linux

# ketchup 2.6-tip

2.6.17.6 -> 2.6.17.7

Applying patch-2.6.17.6.bz2 -R

Applying patch-2.6.17.7.bz2

That’s really it. It will download the patches, revert and apply them, so all you will have to do is watch and wait

Switching to an entirely different kernel versions is just as easy:

# cd /usr/src/linux

# ketchup 2.6.16.2

Final note: If Ketchup should abort with a gpg error, then it couldn’t verify the patch’s or kernel’s signature. Either add the 2.6 public key to your keyring (this is the proper solution) or call Ketchup with an additional -G parameter (this will override signature checking). I’d suggest the former, which is really easy to do by downloading it from a public pgp server:

# gpg --keyserver wwwkeys.pgp.net --recv-keys 0x517D0F0E

Have fun compiling,

You can check if mod_rewrite is compiled in with Apache doing:

httpd -l | grep mod_rewrite.c

If it’s not then you should re-compile Apache.

You could also enable mod_rewrite logging:

RewriteLog “/var/log/httpd/rewrite.log”
RewriteLogLevel 9 # Maximum debug level, should be disabled on production environment

Note that this must be added on the VirtualHost or at the httpd.conf and *NOT* in the .htaccess.

After this you can check the file /var/log/httpd/rewrite.log to see what happens when you try to access an URL that should be rewritten.

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Scenario: A linux server running Debian Sarge 3.1 setup according to Falko’s – The Perfect Setup – Debian Sarge (3.1).
Let’s assume we have one working website (www.example.com) and that the document root is: /var/www/www.example.com/web
The IP of the server is 192.168.0.5 and it’s using eth0 as network interface name.

Needed programs and files

• Snort
• Snort rules
• PCRE (Perl Compatible Regular Expressions)
• LIBPCAP
• BASE (Basic Analysis and Security Engine)
• ADOdb (ADOdb Database Abstraction Library for PHP (and Python).)

Downloading and untaring

We need a temporary place for all the files that we are going to download, and untar.
To keep things simple we will create a directory in the /root named snorttemp. (It’s obvious that this download directory can be any name and in anyplace)

cd /root
mkdir snorttemp
cd snorttemp

Now you need to get Snort.
The latest version at the time of writing this is 2.6.0

wget http://www.snort.org/dl/current/snort-2.6.0.tar.gz

When the download is finished untar the file:

tar -xvzf snort-2.6.0.tar.gz

And let’s remove the tar file:

rm snort-2.6.0.tar.gz

We also need the Snort rules!
Go to: http://www.snort.org/pub-bin/downloads.cgi and scroll down till you see the “Sourcefire VRT Certified Rules – The Official Snort Ruleset (unregistered user release)” rules
(If you are a member of the forum you can also download the – registered user release):

wget http://www.snort.org/pub-bin/downloads.cgi/Download/vrt_pr/snortrules-pr-2.4.tar.gz

Move the snortrules-pr-2.4.tar.gz into the snort-2.6.0 map:

mv snortrules-pr-2.4.tar.gz /root/snorttemp/snort-2.6.0

and cd into snort-2.6.0:

cd snort-2.6.0

Untar the snortrules-pr-2.4.tar.gz file:

tar -xvzf snortrules-pr-2.4.tar.gz

Remove the tar file:

rm snortrules-pr-2.4.tar.gz

We are done downloading the files needed to get Snort to work.

To make snort work with BASE, we need more!

PCRE – Perl Compatible Regular Expressions.

Go to: http://www.pcre.org/ and select a download link for the pcre-6.3tar.gz file to download PCRE (at time of writing this it is pcre-6.3.tar.gz)
cd back to the snorttemp map:

cd /root/snorttemp

and download the pcre-6.3.tar.gz file:

wget http://surfnet.dl.sourceforge.net/sourceforge/pcre/pcre-6.3.tar.gz

Untar the file:

tar -xvzf pcre-6.3.tar.gz

Remove the tar:

rm pcre-6.3.tar.gz

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1) To display message “Disk failure system will be down for 30 minute” to all users use wall as follows:
# wall
Disk failure system will be down for 30 minute
--UNIX Admin
--MyCorp.com


When the message is complete, press Control-D (CTRL+D) to send message to all user.

2) To display message “Web server under DOS attack, come to IDC # 3″ to all WHEEL group member use wall command with –g option as follows:
# wall –g wheel
Web server under DOS attack, come to IDC # 3 to investigate matter further.
-- IT HEAD

When the message is complete, press Control-D (CTRL+D) to send message to all user.