gnegg: April 2005

Snom 190

The Snom 190 is a SIP hardware phone which I have ordered recently to continue my asterisk experiment.

Yesterday it arrrived.

I have to say: I love that device. Contrary to those proprietary PBX phones, the Snom 190 is easy to use, provides a big heap of features (complete remote managability, web interface, dialing over http-request (outlook-plugin – here I come)) and does not cost more than what the other companies ask for their lowest entry level phones. The Snom even looks good!

Like many other devices today, the Snom 190 runs Linux (2.4), though this time I have not tried to hack it yet. All the sources including the developement environement are available at the website of snom.

Contrary to the somewhat crappy ZyXel 2000W which I have tested too, the Snom 190 is ready for productive business.

This makes implementing VoIP at our company seem more and more likely every day.

The greatest gadget ever

Recently I though: “well… having this iMac as server is all nice and well, but what about having all that a little more like embedded? What about not having to have this iMac running all the time? After all, it is not always as silent as I would have whished it to be. And I really wanted to have something more “hackish”

So I went after the Linksys WRT54G. There are two ROM’s you can flash on it: On one hand the more or less proprietary ROM by Sveasoft and on the other hand the ROM by OpenWRT, the last one being the only one actually allowing to install packages.

I bought myself one of those linksys-thingies and I was less then pleased. The ROM by Sveasoft worked well by adding some extended features to the device, but not allowing me to install anything (or even change configuration files). OpenWRT fixed that readonly-thing, but I could not get WPA to work.

After all, the device is of limited use as a home-server. The storage you have at your disposal is just too limited, so I went out to fix that problem.

The fist thing that came to my mind is one of those “Network Harddrives” – poor mans NAS.

I went to one of those big retailers and found the Linksys NSLU2, which enables externally plugged USB-drives to be exported via CIFS (or SMB or SAMBA or whatever you call it).

Before doing anything with the device – having in mind Linksys’ relation to Linux, I googled around a bit and found NSLU2 Linux

After getting it installed (the root-password thing was a bit tricky, but consequent RTFM helped here), I was slowly getting very, very impressed.

What you get is the usual down-stripped linux-distribution, but the root-fs is writable, so you can change the configuration in-place. Then, you can use the attached harddrive as storage for additional software, thus working around the single problem I’ve had with the wrt54g: In-extensibility

After you install the basic distribution, there’s little more than 1 MByte of free space on the flash-rom of the device itself. But there’s this script, unslug that enables the device plugged to the first USB-port as storage for additional software. And additional software, there’s plenty of.

After installing the package unslug-feeds (with ipkg install unslug-feeds) you gain access to this repository containing software like Apache, PHP, Postgresql, a bittorrent-client, cups, perl (for Slimp3),… just all you need on a decent linux distribution (and more less-useful stuff like OpenLDAP). You even get asterisk – and there’s a way to install additional USB-drivers. If only AVM would provide kernel modules for the ARM-kernel running on the device. Then, the NSLU2 would be the smallest PBX on this planet.

The best thing is: While the firmware by linksys does not allow it, with the improved version, you can plug an USB-Stick into the first USB-port and use that as target for additional software installation.

This allows for installing a complete linux distribution on a device with no mechanical parts whatsoever. No PC you’re going to build yourself will even be so silent. Neither is my iMac. Finally a home-server not making any sound at all. This is great.

Because I have no USB-stick at hand, I have not run unslug yet, but I will tomorrow.

Then I’m going to plug my newly bought external 250GB harddisk to the second USB-port and use that for storage for a bittorrent client I’m eventually going to install on the USB stick. And for my MP3’s which a Squeezebox-Server installed on the USB-Stick will serve. So, when I’m not asleep, I turn on the HDD to serve MP3’s to the Squeezebox. When I’m going to sleep, I just turn the HD off, keeping the rest of the server running.

This little device is so extremely great. I really really like it so far and I can’t wait to see it to work at it’s fullest potential.

This is the best CHF 150.- I’ve ever spent in my whole live.

Praise to ZSH

Jochen Maes talks about zsh today. (I found that blog via planet.gentoo.org)

I wholeheartly agree with Jochen here.

Finally someone else writing good stuff about zsh.

I’m using this shell since 2000 where I did my first serious steps with Unix. This mainly has three reasons:

One is the “User Friendly Users Guide” available here. Besides this being an excellent introduction to zsh it is one to unix shells in general. When you’re learning unix shells using this guide, you’ll somewhat automatically stay with zsh.

The other reason is the great flexibility and expandibility. Zsh had a programmable autocomplete-feature long before bash had (or at least long before it was generally known) and even better: It came with some autocompletition functions already enabled for some tools (like tar or even scp). Programmable autocompletition allows you create special autocompletitions depending on the context you are hitting tab.

So let’s say if you are beginning to type

$ scp gnegg.dat pilif@server.example.com:~/gn

and then hit tab, zsh will actually autocomplete on the remote server(!) and create

$ scp gnegg.dat pilif@server.example.com:~/gnegg

for you (assuming that directory exists)

The same goes for tar (even with .gz or .bz2 compressed ones). Or cvs or svn

While gentoo provides bash-completition-config which does the same for bash, zsh was there first. And it provides many senseful completitions.

The third reason for me going with zsh is the syntax of the shell-scripts which can be configured to be much more intuitive to a C-programmer than the default-syntax, while still being more like ksh/bash than (t)csh.

So for me, switching from bash to zsh was a no-brainer back in 2000. And as with the text-editors: Once you use a certain tool, you will not change it afterwards.

I strongly recommend you to take a look at zsh too.

Asterisk – it’s getting real

Last week I talked about me and Christoph installing Asterisk on my thinkpad to do a little VoIP-Experiment.

While we were able to create a should-be-working configuration, actually calling to the outside PSTN network did not work. Read the details in my other article.

Last saturday, we fixed that.

There seems to be a problem somehwere between the AVM CAPI Driver and the CAPI layer of the 2.6.11 kernel. After we downgraded to 2.6.10, the problem solved itself without we doing anything more.

So… this was getting interesting…

The first thing I did was to annoy my wonderful girlfriend:



exten => s,1,Wait,1                     ; Wait a second, just for fun

exten => s,2,Answer

exten => s,3,MP3Player(/home/pilif/mp3/3.mp3)

(included into or used as the default context)

Where 3.mp3 is that endlessly stupid song “Tell me” (or whatever it’s called) by britney spears (this is an insider-joke – both of us just hate that song). Then I told her to call that number…

While this example is completely pointless, it was fun to watch my girlfriend connecting and listening to the song (which soon ended in a disconnection log entry)



exten => s,1,Wait,1

exten => s,2,Dial(SIP/12345,60,tr)

exten => s,3,Congestion

This makes much more sense and directs all incoming calls to the SIP-Phone 12345 as configured in sip.conf. After 60 seconds, it sends back a congestion signal. The first entry would not be necessary, but I hate it when I call somewhere and the phone is answered just at the first ring. So in my PBX, the answering party will wait one second before directing to the sip-phone.

In musiconhold.conf I’ve configured madplay as my MP3-Player for music on hold:



default => custom:/home/pilif/mp3/,/usr/bin/madplay --mono -R 8000 --output=raw:-

madplay is much better than mpg123 used per default as it accepts VBR encoded input and bitrates > 128 kbit which is what nearly all of my MP3’s are encoded with.

In zapata.conf enable music on hold with musiconhold=default in [channels]

The next thing was an optimization of the SIP-Phone used…

X-Lite is nice, but in the end it’s just a demo for other products by the same vendor. Call transferring is not possible for example, which is what we wanted to try next.

The best soft phone we’ve seen so far is SJPhone. A configuration guide is here

But the real clou is the Zyxel 2000W phone that’s currently on my desk: The phone has a WLAN interface (unfortunately no WPA support) and can perfectly well speak with asterisk.

The phone has some problems though: it’s slow, it has no support for call transferring, nor holding, neraly every configuration change causes it to reboot,… In the end I really hope Zyxel will further improve the firmware, which is what they seem to be doing – the current release is from the end of february, so quite current.

The next thing will be trying to install a webbased frontend to asterisk and creating a real dialplan with voice mail. Then, our experiment will be over and we’ll see how it can be put into practical use (like finally getting rid of the old, proprietary PBX from alcatel of our landlords)