HowtoForge - Linux Howtos and Tutorials - Linux

How To Utilize Your New Multimedia Keyboard Under Linux

Fri, 27 Apr 2007 16:36:44 +0200

How To Utilize Your New Multimedia Keyboard Under Linux

Xbindkeys is a program that allows you to launch shell commands with your keyboard or your mouse under X Window. It links commands to keys or mouse buttons, using its configuration file. It does not depend on the window manager and can capture all keyboard keys.

Create Users And Change Passwords With A Bash Script

Fri, 16 Mar 2007 16:33:09 +0100

Create Users And Change Passwords With A Bash Script

These two scripts are very important for the system admin who regularly works with mail servers and somehow forgets to backup his system username and password! Let’s say somehow we lost the usernames and passwords of the mail server. In this case the admin has to manually create all the users and then change the passwords for all the users. Tedious job. Let’s make our life easier.

Setting the SUID/SGID bits: Giving a program YOUR permissions when it runs

Fri, 02 Mar 2007 14:57:47 +0100

Setting the SUID/SGID bits: Giving a program YOUR permissions when it runs

Normally, when a program runs under Linux, it inherits the permissions of the user who is running it, thus if I run a program under my account, the program runs with the same permissions that I would have if that program were me. Thus, if I cannot open a certain file, the program I am running also cannot open the file in question. If I set the SUID or SGID bit for a file, this causes any persons or processes that run the file to have access to system resources as though they are the owner of the file.

Using TAR with Bunzip2 files

Fri, 02 Mar 2007 14:41:01 +0100

Using TAR with Bunzip2 files

Bunzipping and then unTARring in two steps is not convenient.

It is not necessary to use Bunzip2 and then TAR to unzip a file in two separate steps.

Tar will do the job on its own if the -j switch is used, thus:

tar xjvf linux-source<version>.tar.bz2

By the same token, you may use the -z switch with a gzipped file, e.g.

tar zxvf linux-source<version>.tar.gz

Cisco 350 Series And Kismet

Fri, 24 Nov 2006 15:20:47 +0100

Cisco 350 Series And Kismet

This tutorial is describing how to configure a Cisco Aironet wireless card and how to set up kismet in order to run with it.

Step-By-Step Configuration of NAT with iptables

Wed, 08 Nov 2006 19:53:03 +0100

Step-By-Step Configuration of NAT with iptables

This tutorial shows how to set up network-address-translation (NAT) on a Linux system with iptables rules so that the system can act as a gateway and provide internet access to multiple hosts on a local network using a single public IP address. This is achieved by rewriting the source and/or destination addresses of IP packets as they pass through the NAT system.

How do I start the X server in Suse 9.2 when the graphic card is working work in text mode?

Mon, 07 Aug 2006 17:03:40 +0200

To start the X server from a text mode session, execute the command:

startx

How do I find out if a remote system is still alive, if certain services are running, which processes are running, etc.?

Mon, 07 Aug 2006 16:58:36 +0200

You can use ping to see if the system is alive:

ping -c4 <system's IP address>

To see if a certain service is still alive, use the telnet command:

telnet <system's IP address> 25 (for SMTP)

telnet <system's IP address> 80 (for HTTP)

telnet <system's IP address> 110 (for POP3)

You can login to the system using SSH (port 22) (use PuTTY if you are on a Windows PC; PuTTY is an SSH client for Windows), and when you are on the system, you have a few useful tools to gather more information:

How do I scan my Linux system for rootkits, worms, trojans, etc.?

Mon, 07 Aug 2006 16:48:39 +0200

Either with chkrootkit or with rkhunter.

chkrootkit

Either install the package that comes with your distribution (on Debian you would run

apt-get install chkrootkit

), or download the sources from www.chkrootkit.org and install manually:

wget --passive-ftp ftp://ftp.pangeia.com.br/pub/seg/pac/chkrootkit.tar.gz
tar xvfz chkrootkit.tar.gz
cd chkrootkit-<version>/
make sense

Afterwards, you can move the chkrootkit directory somewhere else, e.g. /usr/local/chkrootkit:

How can I get a list of quotas assigned to my users and groups and of the space used by them?

Mon, 07 Aug 2006 16:45:48 +0200

repquota -avug

shows a list for both users and groups.

repquota -au

shows a list for users,

repquota -ag

a list for groups.

How can I set a limit as to how much space is available for a web site I put on my server? Like it is limited to 50 MB of space.

Mon, 07 Aug 2006 16:39:52 +0200

First, you have to enable quota on your system. Have a look at the quota section of the appropriate "Perfect Setup" tutorial for your distribution on HowtoForge.

After you've enabled quota on your system:

To set quotas for a user or group, use the setquota command (see

man setquota

for more information), e.g.:

setquota -g $group $blocks $blocks 0 0 -a
setquota -u $username $blocks $blocks 0 0 -a

Replace $group, $username and $blocks. Note: $blocks is the quota size in MB * 1024! To deactivate quotas for a user or group, run these commands and set $blocks to 0.

Quota does not work under SuSE 8.2!

Mon, 07 Aug 2006 16:33:53 +0200

On a standard SuSE 8.2 installation the quota module is not loaded into the kernel which is why

quotaon -avug

gives back an error.

Load the quota module manually with

insmod quota_v1

and

insmod quota_v2

To have those modules loaded on every bootup of the system please insert

modprobe quota_v1

and

modprobe quota_v2

in /etc/init.d/boot.local.