Lik`s forum

Enable date-stamp in your .bash_history file

While it’s easily cleared by a malicious person, this can easily extend the usefulness of your history file with the information of when you ran that command.

This works in bash v3 and up.

If you’d like to add the time-stamping to all users on the machine, the file you’d want to edit is probably /etc/profile. If not, add it to your .bash_profile in your home directory (~).

Add ...

Suppose some program on your system refuses to work or it works, but much slower then you've expected. How can you investigate the reason of such undesirable behaviour? First of all, you can read and analyze logs that this program does (if it does). It's very useful to run unkindly program with --verbose argument or somehow else increase the log level, if the program allows that. But what can you do, if logs are poor ...

Add following line to ~/.bash_profile:

Code: Select all

echo -e 'ALERT - Root Shell Access on:\n' `who -m` '\n' `date` | mail -s "Successfull Root Login" [email protected]

Security-Enhanced Linux, also know as SELinux, implements various security policies on Linux and additional levels of access crontrol. It was originally developed by the U.S. National Security Agency to adhere to the "Orange Book" guidelines. On CentOS 5 it is enabled by default, but there may be circumstances where you don't need SELinux's additional security and may want to disable it.

The SELinux configuration file on CentOS is located at /etc/selinux/config and after a default ...

To clear current session history run the following command:

Code: Select all

history -r

Using the Webmin YUM repository

If you like to install and update Webmin via RPM, create the /etc/yum.repos.d/webmin.repo file containing :

Code: Select all

[Webmin]
name=Webmin Distribution Neutral
baseurl=http://download.webmin.com/download/yum
enabled=1

You should also fetch and install my GPG key with which the packages are signed, with the command :

Code: Select all

rpm --import http://www.webmin.com/jcameron-key.asc

Then we FIRST install SSLeay, or secure connection to webmin server won't be possible

Code: Select all

yum install perl-Net-SSLeay

Finally we install webmin :

Code: Select all

yum install webmin

...

This article is about compiling a kernel on CentOS systems. It describes how to build a custom kernel using the latest unmodified kernel sources from http://www.kernel.org/ (http://en.wikipedia.org/wiki/Vanilla_kernel#Versions) so that you are independent from the kernels supplied by your distribution.

One of the multiple ways of building a kernel for CentOS systems to get you a kernel rpm package that can be installed or shared with others.

Building a Kernel rpm Package

1. Download The Kernel ...

From time to time you will get hanged process or you are unsure of what a process is doing at that moment.

You can trace what a process is doing by running:

Code: Select all

strace -p PID

Where PID is the process ID. Whis will show you what that process is doing in real time.
This is usefull for detecting exploits or the source of a hang process.
To detach from that process simply press CTRL + ...

GRUB supports a fallback mechanism of booting one or more other entries if a default boot entry fails. You can specify multiple fallback entries if you wish.

Suppose that you have three systems, `A', `B' and `C'. `A' is a system which you want to boot by default. `B' is a backup system which is supposed to boot safely. `C' is another backup system which is used in case where `B' is broken.

Then you ...

Managing Linux Software RAID

Marking a damaged disk as failed:

Code: Select all

mdadm --manage --set-faulty /dev/md1 /dev/sdd1

Removing the damaged disk from the array:

Code: Select all

mdadm /dev/md1 -r /dev/sdd1

Shutdown your system, bring it up into single user mode and partition and format your new disk. Set the partition type as Linux Software RAID autodetect. Of course you need to partition your new disk the same as the previous one. Bring the machine up into it's default runlevel, ...