Automatically Bring up an Ethernet Interface at Boot Without IP Address

In order to bring up Ethernet interface "eth1" at boot without IP address, add the following section to the file "/etc/network/interfaces":

auto eth1
iface eth1 inet manual
up ifconfig eth1 up

This tells the system to configure the interface (i.e. eth1) manually. The last line tells the system on bringing the interface up, use the command "ifconfig eth1 up".

Free Music

For any Asterisk deployment, it often needs on-hold music or vivid ring tone music. Free music is a good choice for these purposes.

"Free music is music that, like free software, can freely be copied, distributed and modified for any purpose. Thus free music is either in the public domain or licensed under a free license. It does not mean that there should be no fee involved. The word free refers to freedom (as in free software), not to price." [1]

The following musicians provide free music licensed under Creative Commons: By Attribution 3.0 (http://creativecommons.org/licenses/by/3.0/)

Kevin MacLeod
http://www.incompetech.com/m/c/royalty-free/

Jimmy G
http://www.jimmyg.us/JimmyGMusic/MusicDownloads/tabid/99/Default.aspx

Jonathon Roberts
http://www.jmtr.com/jmtr-royalty-free.html


References:
[1] Free Music, Wikipedia, http://en.wikipedia.org/wiki/Free_music

Install Debian on a Software Raid 1

Steps:

1. Boot the Debian Etch installer.
2. If the installation comes to "Partition method", use "Manual".
3. In the following menu, scroll to your first disk and hit enter: the partitionier asks you, if you want to create an empty partition table. Say "yes". (Hint: this will erase your existing data, if any.)
4. The partitioner is back in the disk overview, scroll one line downwards over the line with "FREE SPACE" and hit enter.
5. Create a partition with the size you need. Select "Primary" for type for the new partition. Select "Beginning" for the location for the new partition.
   
6. In the "Partition settings" menu, go to "Use as" and hit enter.
7. Change the type to "physical volume for RAID".
8. Finish this partition with "Done setting up the partition".
9. Create other partitions on the same disk, if you like.
10. Now repeat all the steps from the first disk for the second disk.
11. After this, you should have at least two disks with the same partition schema and all partitions should be marked for RAID use.
12. Now look at the first menu entry in the partitioner menu, there is a new line: "Configure software RAID". Go into this menu.
13. Answer the question, if you like to write the changes, with "Yes".
14. Now pick "Create MD device".
15. Use RAID1 and give the number of active and spare devices (2 and 0 in our case).
16. In the following menu, select the same device number on the first and second disk and Continue.
17. Repeat this step for every two devices until you are done. Then use "Finish" from the Multidisk configuration options.
18. You are back in the partitioner menu and now you see one ore more new partitions named as "Software RAID Device". You can use this partitions like any normal partition and continue installing your system.

Install boot loader (grub) on the second hard drive:

1. Start the grub command shell:
   # grub
2. At the 'grub>" shell prompt create new boot record for the second drive:
   root (hd1,0)
   setup (hd1)
   quit
   

View RAID status:
# cat /proc/mdstat
or
# mdadm -D /dev/md0

Add a drive to RAID device:
# mdadm --add /dev/md0 /dev/sda1

References:

1. Install Debian Etch on a Software Raid 1 with S-ATA disks
2. Monitoring and Managing Linux Software RAID
   

"rtc: lost some interrupts at 1024Hz." Messages Again

I got a lot of "rtc: lost some interrupts at 1024Hz." messages after installed zaptel-1.4.11 and the ztdummy module was enabled.

The PC platform details:
- Debian GNU/Linux 4.0r1 on i386 with update applied
- Shuttle KPC K45 Barebones
- CPU Celeron C430 1.8 GHz

I can fix this problem by applying the method in my previous post on 6-Oct-2007. However, when I press the power button, the system power off immediately instead of a clean shutdown. After a lot tries, I still cannot fix the power button problem.

Finally, I reinstall the system using Debian GNU/Linux 4.0r3 on Amd64 (i.e. 64-bit version). The "rtc: lost some interrupts at 1024Hz." never occur again.

Change Debian to Use Local Time Instead of UTC

In /etc/default/rcS, set UTC=no.

VoIP Trouble Shooter

Voice over IP performance is sensitive to both IP network behavior and traditional telephony problems. Network managers need new tools and techniques to help with VoIP troubleshooting and problem resolution in order to maintain good quality services.

The following site contains information on how to troubleshoot VoIP problems, free online diagnostic tools and useful background information on voice quality and packet statistics.

http://www.voiptroubleshooter.com/index.html

IPCop + Asterisk

The following article describes how to combine the IPCop and Asterisk:

http://www.cupovoip.com/docs/asterisk-installation-ipcop-english.html

Cloning Hard Disks for Linux

Cloning Hard drives using G4L and Knoppix
http://bhavesh.freeshell.org/cloninghd.html

linux系统GHOST备份方案
http://www.nixsky.com/linux/qitafaxingban/2007-06/194.html

Sending Files as Email Attachments

The following article describes various methods of sending files as email attachment in Linux command line:

http://www.shelldorado.com/articles/mailattachments.html

Asterisk: The Future of Telephony, Second Edition ebook

http://downloads.oreilly.com/books/9780596510480.pdf

Ethernet Bridge

A bridge is a way to connect two Ethernet segments together in a protocol independent way. Packets are forwarded based on Ethernet address, rather than IP address (like a router). Since forwarding is done at Layer 2, all protocols can go transparently through a bridge.

Bridging is supported in the current Linux kernels (2.4 and 2.6) from all the major distributions. The required administration utilities are in the bridge-utils package in most distributions.

Setup an Ethernet bridge in Debian

1. Install two Ethernet LAN cards in a PC with Debian installed. The original LAN card is named "eth0" and the newly installed LAN cards are named "eth1" and "eth2".
   
2. Install the bridge administration tools:
   # apt-get install bridge-utils
3. Setup a bridge between eth1 and eth2 by the following commands:
   # ifconfig eth1 0.0.0.0
   # ifconfig eth2 0.0.0.0
   # brctl addbr br0
   # brctl addif br0 eth1
   # brctl addif br0 eth2
   # ifconfig br0 up

http://www.linux-foundation.org/en/Net:Bridge

Network Emulation

"Netem"provides network emulation functionality for testing protocols by emulating the properties of wide area networks. The current version emulates variable delay, loss, duplication and re-ordering.

Netem is already enabled in Linux kernel 2.6 and it is controlled by the command line tool "tc" which is part of the iproute or iproute2 package of tools.

http://www.linux-foundation.org/en/Net:Netem

In Debian, we need to install the iproute package in order to use "tc":
# apt-get install iproute

Another famous network emulation tool is "NIST Net":
http://www-x.antd.nist.gov/nistnet/

How To Set Up A Debian Linux Fax Server?

http://www.aboutdebian.com/fax.htm