Network administrators frequently use the Lightweight Directory Access Protocol (LDAP) to implement a centralized directory server. You can use LDAP to authenticate users in Apache. Two popular open source LDAP solutions are OpenLDAP and Red Hat Directory Server. According to the Apache documentation, Novell LDAP and iPlanet Directory Server are also supported. This article focuses on OpenLDAP, but the concepts and examples should be applicable to the others.
Explains how to use scrub software to erase hard disk data under Linux / UNIX operating system by following dod 5220.22-m / NNSA NAP-14.x compliant utilities.
From my mail bag:
I’ve downloaded .avi files which is compressed into small sizes while maintaining relatively high visual quality using DivX format. How do I play DivX compressed files under Debian / Ubuntu Linux?
The current version of the DivX Community Codec for the Windows platform is version 6.6, and for Mac OS X is 6.6x. There is no Linux version available however with the help of VLC and DivX for Linux codec, you should able to play all sort of DivX files.
Download and Install DivX Linux Codec
Open terminal and type the following command to download DivX codec:
$ cd /tmp
$ wget http://download.divx.com/labs/divx611-20060201-gcc4.0.1.tar.gz
Untar DivX 6.1.1 codec for Linux:
$ tar -zxvf divx611-20060201-gcc4.0.1.tar.gz
Install divx611 codec:
$ cd divx611-20060201-gcc4.0.1
$ sudo ./install.sh
Press Q after reading agreement, please type yes to install codes.
Install vlc player
The VLC media player can be installed using apt-get command, type:
$ sudo apt-get update
$ sudo apt-get install vlc
How do I play files?
Open VLC player by Visiting Applications > Sound and Video > VLC Player. You can also open terminal and type the command:
$ vlc /path/to/my-downloaded-movie.avi
Internet SCSI (iSCSI) is a network protocol s that allows you to use of the SCSI protocol over TCP/IP networks. It is good alternative to Fibre Channel-based SANs. You can easily manage, mount and format iSCSI Volume under Linux. It allows access to SAN storage over Ethernet.
Open-iSCSI project is a high-performance, transport independent, multi-platform implementation of iSCSI. Open-iSCSI is partitioned into user and kernel parts.
Instructions are tested on:
[a] RHEL 5
[b] CentOS 5
[c] Fedora 7
[d] Debian / Ubuntu Linux
Install Required Package
iscsi-initiator-utils RPM package – The iscsi package provides the server daemon for the iSCSI protocol, as well as the utility programs used to manage it. iSCSI is a protocol for distributed disk access using SCSI commands sent over Internet Protocol networks. This package is available under Redhat Enterprise Linux / CentOS / Fedora Linux and can be installed using yum command:
# yum install iscsi-initiator-utils
A note about Debian / Ubuntu Linux
If you are using Debian / Ubuntu Linux install open-iscsi package, enter:
$ sudo apt-get install open-iscsi
There are three steps needed to set up a system to use iSCSI storage:
- iSCSI startup using the init script or manual startup. You need to edit and configure iSCSI via /etc/iscsi/iscsid.conf file
- Discover targets.
- Automate target logins for future system reboots.
- You also need to obtain iSCSI username, password and storage server IP address (target host)
Step # 1: Configure iSCSI
Open /etc/iscsi/iscsid.conf with vi text editor:
# vi /etc/iscsi/iscsid.conf
Setup username and password:
node.session.auth.username = My_ISCSI_USR_NAME
node.session.auth.password = MyPassword
discovery.sendtargets.auth.username = My_ISCSI_USR_NAME
discovery.sendtargets.auth.password = MyPassword
- node.session.* is used to set a CHAP username and password for initiator authentication by the target(s).
- discovery.sendtargets.* is used to set a discovery session CHAP username and password for the initiator authentication by the target(s)
You may also need to tweak and set other options. Refer to man page for more information. Now start the iscsi service:
# /etc/init.d/iscsi start
Step # 2: Discover targets
Now use iscsiadm command, which is a command-line tool allowing discovery and login to iSCSI targets, as well as access and management of the open-iscsi database. If your storage server IP address is 192.168.1.5, enter:
# iscsiadm -m discovery -t sendtargets -p 192.168.1.5
# /etc/init.d/iscsi restart
Now there should be a block device under /dev directory. To obtain new device name, type:
# fdisk -l
# tail -f /var/log/messages
Oct 10 12:42:20 ora9is2 kernel: Vendor: EQLOGIC Model: 100E-00 Rev: 3.2 Oct 10 12:42:20 ora9is2 kernel: Type: Direct-Access ANSI SCSI revision: 05 Oct 10 12:42:20 ora9is2 kernel: SCSI device sdd: 41963520 512-byte hdwr sectors (21485 MB) Oct 10 12:42:20 ora9is2 kernel: sdd: Write Protect is off Oct 10 12:42:20 ora9is2 kernel: SCSI device sdd: drive cache: write through Oct 10 12:42:20 ora9is2 kernel: SCSI device sdd: 41963520 512-byte hdwr sectors (21485 MB) Oct 10 12:42:20 ora9is2 kernel: sdd: Write Protect is off Oct 10 12:42:20 ora9is2 kernel: SCSI device sdd: drive cache: write through Oct 10 12:42:20 ora9is2 kernel: sdd: unknown partition table Oct 10 12:42:20 ora9is2 kernel: sd 3:0:0:0: Attached scsi disk sdd Oct 10 12:42:20 ora9is2 kernel: sd 3:0:0:0: Attached scsi generic sg3 type 0 Oct 10 12:42:20 ora9is2 kernel: rtc: lost some interrupts at 2048Hz. Oct 10 12:42:20 ora9is2 iscsid: connection0:0 is operational now
/dev/sdd is my new block device.
Step # 3: Format and Mount iSCSI Volume
You can now partition and create a filesystem on the target using usual fdisk and mkfs.ext3 commands:
# fdisk /dev/sdd
# mke2fs -j -m 0 -O dir_index /dev/sdd1
# mkfs.ext3 /dev/sdd1
Tip: If your volume is large size like 1TB, run mkfs.ext3 in background using nohup:
# nohup mkfs.ext3 /dev/sdd1 &
Mount new partition:
# mkdir /mnt/iscsi
# mount /dev/sdd1 /mnt/iscsi
Step #4: Mount iSCSI drive automatically at boot time
First make sure iscsi service turned on at boot time:
# chkconfig iscsi on
Open /etc/fstab file and append config directive:
/dev/sdd1 /mnt/iscsi ext3 _netdev 0 0
Save and close the file.
- Official Open iSCSI documentation
- Read iscsiadm and related man pages
This article explains some of the more important syntactic and semantic differences between two of the most popular assemblers for LinuxÂ®, GNU Assembler (GAS) and Netwide Assembler (NASM), including differences in basic syntax, variables and memory access, macro handling, functions and external routines, stack handling, and techniques for easily repeating blocks of code.
Unlike other languages, assembly programming involves understanding the processor architecture of the machine that is being programmed. Assembly programs are not at all portable and are often cumbersome to maintain and understand, and can often contain a large number of lines of code. But with these limitations comes the advantage of speed and size of the runtime binary that executes on that machine. Even though the differences between these two assemblers are substantial, it’s not that difficult to convert from one form to another. You might find that the AT&T syntax seems at first difficult to understand, but once mastered, it’s as simple as the Intel syntax.