New thoughts on streaming music

Writing up the procedure I use to stream music got me thinking about problems with it and alternatives. One problem that it has is that I must be logged in on the console, in X, running xmms. A power-outage forced reboot could end my musical bliss at work ;). Someone else pointed out that I really should consider ogg. While re-encoding all my source CD's would be a massive undertaking this would eventually be a good goal. Transcoding from mp3->ogg is a bad idea but for a low quality stream it may have little impact.

So I found gnump3d and liked what I saw. So I installed it, reconfigured some firewall rules, and liked it even more. This is a web-based way to control and stream an music collection. The web interface is well-designed and skinnable. It seems to give me more control than xmms-shell. I can cue up individual songs or albums. Each song is a playlist so I can easily scramble within my xmms client at work rather than on the server. I can create customer playlists through the web interface.

The coolest feature is the way resampling is handled. The parameters for resampling (called downsampling in gnump3d.conf allow you to specify subnets that do not require downsampling. Thus I can fire up a session on my local desktop and use it to control music and those songs will not be re-encoded to a lower bitrate. The cacheing that happens between each song due to stream is instantaneous on a local connection so album play is minimally interrupted.

gnump3d doesn't utilize a MySQL or other backend database. It's very simple to setup and has taken some reasonable security precautions. I like it's "keep it simple" approach.

It doesn't work well through the reverse inbound proxy so I run it through an alternate port on the firewall and redirect that to the internal gnump3d server. One way I could deal with this is switch to Apache::MP3. This is a mod_perl solution that runs within Apache. So even SSL-encrypted streaming could work through this. Port 80 name-based virtual hosts work fine Apache::MP3::Skin and Apache::MP3::Resample would provide the additional similar functionality. A user can choose the level of resampling desired so it's pretty interesting.

Since gnump3d works so well for me I didn't try the Apache perl module approach but I may mess with it at a layer time. I've been experimenting with mod_perl stuff for a while so it may be educational to mess with this.

[/Computers/OS/Linux/Tips/#more_streaming_music.html] Comments (0)

Using Procmail as an autoresponder

I'd done this a long time ago and pretty much forgotton all about it. I've used procmail for a long time to pre-sort all my mailing list mail among other tasks. I also use it as a mechanism to distribute my gpg public key. If you send me a message with the subject "get key", you'll get a response containing my public key in ASCII format. Here's a snippet from my .procmailrc:

  VERBOSE=off
  PATH=$HOME:/usr/bin:/bin:/usr/local/bin:.
  MAILDIR=$HOME/Mail      # You'd better make sure it exists
  DEFAULT=/var/mail/scotth
  LOGFILE=$HOME/Mail/from
  LOCKFILE=$HOME/.lockfile
  SENDMAIL=/usr/sbin/sendmail

  :0 Wh: msgid.lock   # get's rid of duplicates
  | formail -D 8192 msgid.cache

  # Autoresponder
  :0i
  * !^Subject:.*Re:
  * !^FROM_DAEMON
  * ^Subject:.*get key
  | (formail -r -A "From: scotth@scottharney.com" ; cat $HOME/.pubkey.asc)\
      | $SENDMAIL -oi -t

  # SpamAssassin 
  :0:
  * ^X-Spam-Status: Yes.*
  $MAILDIR/junk

  # mailing list inet-access
  :0:
  * TO.*inet-access
  $MAILDIR/inet-access

If you just need an autoresponder, you'd just use formail in a .forward. Here's how I do it using a mail server running qmail. Just create ~/alias/.qmail-autorespond containing the following text

| (/usr/local/bin/formail -r -A "From: autorespond@yourdomain.com" ;\
   cat /var/qmail/alias/autoresond.txt) | qmail-inject

[/Computers/OS/Linux/Tips/#procmail-autorespond.html] Comments (0)

Streaming Your Music Collection

If you're like me, you've taken the time to rip your entire music collection to mp3. I have a huge collection of CDs and like to listen to them in the car with my portable mp3 player. I also like to listen to them at work. Since I have a PC and net access, I just stream them and pick the stream up with xmms (or mpg123 or winamp). I use the liveice plugin for Xmms and the Xmms::shell perl module to remotely control the Xmms session and manage playing tunes. There are many ways to do this, but this method works for me

Things you need

• A broadband internet connection.
• Knowledge of firewalls and NAT. My previous article on mod_proxy via apache will also be useful since your typical home setup has just one public IP address.
• To do the above apache mod_proxy trick, you need to understand DNS and have a domain that you control.
• A collection of tunes. Mine is shared on my internal network via NFS and Samba.
• An understanding of streaming technology. The software links below should tell you what you need to know.

What to do

You'll be downloading a pile of software. Everything for me was available as Debian packages so apt-get (packagename) worked for me. I'll link to the original sites here.

First and foremost, you need xmms. You also need icecast. Along with that you'll need liveice and the liveice-xmms plugin. What this will do is send the output of whatever is playing in xmms to your icecast server.

The other thing you'll need is lame because liveice needs to reencode mp3's on the fly. I encode mine for high quality and they're much too large to stream. Thus I re-encode them on the fly to a paltry 64kbps stream. This is bandwidth friendly and my workstation running xmms can more than handle the load.

In Xmms just go to the Options dialog and select the Effects/General plugins tab. From there you can choose to configure and enable the liveice plugin. There are boxes for the stream bitrate (640000 in my case) and the encoder choice (lame)./p>

You're almost set. You need to set up your firewall and/or apache proxy to get the traffic in to your icecast server. Icecast runs by default on port 8000. So for the first option, pass that port through and then you'd connect your remote mp3 software to http://www.yoursite.com:8000 to catch the stream.

Because I'm stuck behind a highly restrictive firewall/http proxy at work, I needed to use the apache proxy magic and DNS. First I set up a new DNS alias pointing to my single IP address -- ie. music.yoursite.com. Then I set my apache mod_proxy on my firewall to pass the traffic through to my internal icecast server (ie. 10.10.1.5 below).

NameVirtualHost your.external.ip.address

<VirtualHost your.external.ip.address>
   ServerAdmin webmaster@yoursite.com
   ServerName music.yoursite.com
   ProxyPass / http://10.10.1.5:8000/
   ProxyPassReverse / http://10.10.1.5:8000/
   ErrorLog /var/log/apache/music.yoursite.net/error_log
   TransferLog /var/log/apache/music.yoursite.net/access_log
<VirtualHost>

So at work I use mpg123 ( I could use any mp3 player really) to connect to my stream remotely: mpg123 -p http://my.work.proxy http://tunes.yoursite.com. If Xmms+liveice-plugin+icecast is running on the server, I get a stream. If not I get a standard HTTP 404 error.

There's one more issue -- remotely controlling that Xmms session. There's lots of ways to do that and the control plugins to xmms are available at the xmms site. I've experimented with some of the web-based plugins and xmms-shell as well. I settled on the perl module Xmms::shell. I can ssh to my site and then use perl -MXmms -e shell to start xmms and manipulate the playlist to my heart's content. I used apt-get libperl-xmms on my Debian setup but non-Debian users might do this:

perl -MCPAN -e shell
CPAN> install Bundle::Xmms

As always, you need to be concerned about security when you start opening holes on your firewall and running new servers. In this case, you've got a firewall, apache, mod_proxy, icecast, and liveice-xmms to be concerned about. That means you've got to watch for vulernabilities in all of these items. This is hardly a mission-critical service so it's no big deal to turn it off should a new vulnerability be discovered. You may also want to restrict it further via your firewall and your apache proxy server using Limit directives in your VirtualHost container.

[/Computers/OS/Linux/Tips/#streaming_music.html] Comments (2)

Using Knoppix and Partimage to "Ghost" whole systems.

Recently at work I needed a way to quickly recover systems from bare metal to a known-good state. These were, of course, Windows2000 boxes. Now there are several commercial solutions to "ghost" a system, but I didn't have funds available to do that.

Enter knoppix. Knoppix is a bootable CDROM distribution of Linux. It has many many uses and is worth investigating. A copy of it stays in my permanent SysAdmin toolchest. One thing it is particularly good at is autodetecting even the most recent hardware. I was pleasantly surprised to find it booted successfully with no manual intervention from me on our Dell PowerEdge 6650's with newish RAID and Gigabit Ethernet devices on board.

Once I booted up, rather than using the traditional unix dd(1) approach to make bit-for-bit drive images, I used the included partimage utility to clone those NTFS partitions. Since partimage knows about filesystem types, it's much more efficient than a bit-for-bit copy. I also had a complication in that I was saving to an temporarily NFS-mounted directory on a Sun server. The details of my procedure, including Linux-Solaris NFS tricks are below

Backing Up Images

Of course you need to get your network connections sorted out first. Boot the server with the Knoppix CD-ROM. Knoppix will come up in a full graphical environment. You, however, will need to work in a terminal console. On the panel bar at the bottom of the screen there is an app called "konsole" (just hold the mouse of the icons to identify them). One click will start it.

Use the following commands to set up network connectivity: First get root

$ sudo bash 

# killall pump 
# ifconfig eth1 192.168.1.254 
# ping 192.168.1.13 PING 192.168.1.13: 56 data bytes 64 bytes from
nfs-server (192.168.1.13): icmp_seq=0. time=0. ms 64 bytes from
nfs-server (192.168.1.13): icmp_seq=1. time=0. ms 

# portmap 

 # mount -t nfs -o nfsvers=2,rsize=8192,wsize=8192,hard,intr \
192.168.1.13:/win2k-image-dir /mnt 

# sfdisk -d > /mnt/server-partlayout.sf 

 # dd if=/dev/sda of=/mnt/server-bootblock.img count=1 bs=512  

# partimage

# sfdisk < /mnt/server-partlayout.sf
# sfdisk -l 

# dd if=/mnt/server-bootblock.img \ 
of=/dev/sda count=1 bs=512

# partimage

# /etc/init.d/rpc start
# /etc/init.d/nfs.server start
# share
-               /share   rw=192.168.1.254   "my share comment"

# /etc/init.d/rpc stop
# /etc/init.d/nfs.server stop
# share

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Scott Harney    (GPG key)
<scott_harney@yahoo.com>

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