Linux Desktop Fun: Summon Swarms Of Penguins To Waddle About The Desktop

Posted on in Categories Linux, Linux desktop last updated July 12, 2011

XPenguins is a program for animating cute cartoons animals in your root window. By default it will be penguins they drop in from the top of the screen, walk along the tops of your windows, up the side of your windows, levitate, skateboard, and do other similarly exciting things. Now you can send an army of cute little penguins to invade the screen of someone else on your network.

Howto: Verify Downloaded Linux / BSD DVD or CD ISO images for integrity

Posted on in Categories CentOS, Debian Linux, Howto, Linux, Linux distribution, RedHat/Fedora Linux, Security, Sys admin, Tip of the day, Ubuntu Linux, UNIX last updated July 26, 2007

You need to verify that that downloaded Linux DVD or ISO images are intact before you burn and use them. This is security feature. But how do you verify ISO images?

Answer is quite simple use md5sum command to compute and check MD5 message digest.

Why verify ISO images?

a) To protect yourself
b) Verify that a file has not changed as a result of file transfer, disk error, cracker attacks, etc.

How does it work?

When you run md5sum command on ISO file, you get checksum (or hash) on screen. You need to compare this checksum with original. It works as a compact digital fingerprint of a file. You can then compare the MD5 hash of your download ISO file, to the known good hash of the file you are checking. If the two values match, you are safe and use the ISO image.

Example

Let us download FreeBSD ISO image:
$ cd /tmp
$ wget ftp://ftp.freebsd.org/pub/FreeBSD/releases/i386/ISO-IMAGES/6.2/6.2-RELEASE-i386-bootonly.iso

Next download MD5 checksum:
$ wget ftp://ftp.freebsd.org/pub/FreeBSD/releases/i386/ISO-IMAGES/6.2/CHECKSUM.MD5

Generate MD5 hash for ISO image

$ md5sum 6.2-RELEASE-i386-bootonly.iso
Output:

4e8701ac951bc4537f8420fdac7efbb5  6.2-RELEASE-i386-bootonly.iso

Verify ISO image

See the known good hash of the file (6.2-RELEASE-i386-bootonly.iso):
$ md5sum -c CHECKSUM.MD5
Output:

6.2-RELEASE-i386-bootonly.iso: OK

You can also use following command for the same purpose:

A note for Windows XP / Vista users

Postfix mail server block Malware with blacklist

Posted on in Categories Howto, Linux, Mail server, Networking, Postfix, RedHat/Fedora Linux, Security, Shell scripting, Suse Linux, Sys admin, Tips, Ubuntu Linux, UNIX last updated June 25, 2007

Malware is used for a malicious purpose. It can be in your software or hardware. Email and pirated software is the most powerful way to spread malware. Malware inserted in a system without user notification.
Continue reading “Postfix mail server block Malware with blacklist”

How To: Extract an RPM Package Files Without Installing It

Posted on in Categories CentOS, Data recovery, Howto, Linux, Linux distribution, package management, RedHat/Fedora Linux, Sys admin, Tips last updated October 18, 2006

As most of you may know to how extract a tarballs and/or a zip files. Someone, recently PM me with a question:

Dear nixCraft,

How do I extract an RPM package without installing it on my Fedora Linux or CentOS or RHEL (Red Hat Enterprise Linux) Suse Linux?

Sincerely,

CentOS user.

Install PHP 5 on Red Hat Enterprise Linux version 4

Posted on in Categories Howto, lighttpd, RedHat/Fedora Linux, Tips last updated October 18, 2006

It appears that many people or sys admin want to run php 5 on Red Hat Enterprise Linux. Unfortunately Redhat does not provide this package (RPM file) for RHEL. You can download source code and install php 5 from official php site. This requires compiler collection on your system. Download source code and just follow instructions presented in INSTALL or REDME file.

Another option is search and installs PHP 5 packages. You can download x86_64 PHP 5 package here. Use wget command to download these packages and rpm command to install new packages. But first remove old php4 package using rpm -e command.

Alert: This post is outdated. Please use the latest version of RHEL/CentOS v6.x+ for PHP 5.x. The author no longer support php 5 rpm on RHEL 4.x.

However these rpm packages 64 bit so if you are running 32 bit os rebuild RPM file.

Step # 1: Download src rpm

# cd /tmp
# wget http://www.cyberciti.biz/files/lighttpd/rhel4-php5-fastcgi/php-5.1.4-1.esp1.src.rpm
# rpm -ivh php-5.1.4-1.esp1.src.rpm

Step #2: Rebuild RPM for 32 bit RHEL version

# cd /usr/src/redhat/SPECS
# rpmbuild -bb php.spec

It will take some time to compile and rebuild RPM files.

Step #3: Install new php5 RPM file

Remove old php4 rpm. Go to /usr/src/redhat/RPMS directory and install PHP5 RPM files.

Please note that PHP 5 is not official supported by Red Hat on RHEL 4.0. You are using these packages on your own risk 😉