A few weeks ago VMware released their free VMware Server Beta virtualization software which I downloaded and installed on my little Debian slave, an AMD Duron 1300 with 512MB RAM. This machine normally holds backups of my main computer and serves as a general purpose Linux box and webserver for me at home. Well, I had to learn that there is still much more that you can do with it.

Every now and then I wished to have more than one Linux box so that I could easily try something out and get rid of it afterwards without touching my default installation. And, yes, very seldom I’d like to have a Windows 98 environment to compile and test an older piece of software. But yet I was neither willing to provide a third computer for that nor to struggle with drive images or multi-boot setups.

And now these wishes become true at no cost with VMware Server. You see, I am excited. So I took the following screenshots to demonstrate how simple a new virtual machine can be brought to life. The shots are taken from VMware Server Console running on my Windows XP main machine to control the Debian slave with VMware Server.

You may complain about the one or another shot being redundant, but my intention is to also produce an authentic impression of this beautiful installation process that we all got to like that much over the years. Of course, the good old Windows 98 startup disk had been prepared and inserted into Debian slave’s disk drive ;-)

Imagine you set up dozens of virtual hosts and want each of them to have an individual default password for a protected area, i.e. a logfile directory being accessible via http://vhost/logs/. Putting .htaccess files into the target directories is step one and fairly simple. Whereas step two, adding the .htpasswd files, may end up unhandily, either juggling with cleartext and encrypted passwords or falling back on system() calls of htpasswd(2).

The example below shows how this can be handled with the modules Apache::Htpasswd and String::Random. Just provide a filename and a username, the subroutine will create the .htaccess file, add the user with a new random password and return the cleartext password to be handed out to your customer.

use String::Random;
use Apache::Htpasswd;

sub DefaultHtpasswd($$) {
  my($Filename,$Username) = @_;

  my $RandomString = new String::Random;
  my $PasswdString = $RandomString->randpattern('nnCcCnCc');

  my $Htpasswd = new Apache::Htpasswd($Filename);

  $Htpasswd->htpasswd($Username, $PasswdString, 1)
  or die($Htpasswd->error);

  return($PasswdString);
}

Below is a piece of code that I wrote a while ago when setting up a backup mechanism to automatically retrieve (and put) configuration files from (or to) Cisco Catalyst switches (running CatOS).

Usually, as a perl programmer with a new challenge, you will first do a search on CPAN and almost probably find the answer or at least a hint. But at that time I decided not to go for the Cisco::Conf module that uses telnet instead of SNMP commands and operates in writeNet mode. Today, the more recent Cisco::CopyConfig should be the module of choice, but it uses ccCopy mode and works for IOS devices only.

My example uses tftpGrp mode, a third variant, that has not yet been packed in a module.

Short explanation: Subroutine, give it your Catalyst’s hostname or IP address ($Host) and SNMP write community string ($Cty), the TFTP server’s hostname or IP address ($Server) and the filename on TFTP server ($Filename). The action ($Action) to be performed by Catalyst is given in clear text, see %Actions for allowed values. Module number ($Module) and timeout in seconds ($Timeout) are optional arguments and default to standard values if omitted. Returns result in clear text, see %Results for possible values.

Don’t forget to touch and chmod 666 file on TFTP server before transfer and remove it afterwards. Have fun!

use Convert::BER;
use Net::SNMP;

sub tftpGrp {
  my($Host,$Cty,$Server,$Filename,
     $Action,$Module,$Timeout) = @_; 
  ################################
  my %OIDs = (
   'tftpHost'   => '1.3.6.1.4.1.9.5.1.5.1.0',
   'tftpFile'   => '1.3.6.1.4.1.9.5.1.5.2.0',
   'tftpModule' => '1.3.6.1.4.1.9.5.1.5.3.0',
   'tftpAction' => '1.3.6.1.4.1.9.5.1.5.4.0',
   'tftpResult' => '1.3.6.1.4.1.9.5.1.5.5.0',
  );

  my %Actions = (
   'other'          => 1,
   'downloadConfig' => 2,
   'uploadConfig'   => 3,
   'downloadSw'     => 4,
   'uploadSw'       => 5,
   'downloadFw'     => 6,
   'uploadFw'       => 7,
  );

  my %Results = (
   1  => 'inProgress',
   2  => 'success',
   3  => 'noResponse',
   4  => 'tooManyRetries',
   5  => 'noBuffers',
   6  => 'noProcesses',
   7  => 'badChecksum',
   8  => 'badLength',
   9  => 'badFlash',
   10 => 'serverError',
   11 => 'userCanceled',
   12 => 'wrongCode',
   13 => 'fileNotFound',
   14 => 'invalidTftpHost',
   15 => 'invalidTftpModule',
   16 => 'accessViolation',
   17 => 'unknownStatus',
   18 => 'invalidStorageDevice',
   19 => 'insufficientSpaceOnStorageDevice',
   20 => 'insufficientDramSize',
   21 => 'incompatibleImage',
  );
  ################################
  $Action  = $Actions{$Action} or return(undef); 
  $Module  =  1 unless(int($Module));
  $Timeout = 10 unless(int($Timeout));

  my($Session,$Error) = Net::SNMP->session(
    -version   => 'snmpv2c',
    -hostname  => $Host,
    -community => $Cty
  );
  return($Error) unless(defined($Session));

  $Session->timeout($Timeout);

  $Session->set_request($OIDs{'tftpHost'},OCTET_STRING,$Server);
  $Session->set_request($OIDs{'tftpFile'},OCTET_STRING,$Filename);
  $Session->set_request($OIDs{'tftpModule'},INTEGER,$Module);
  $Session->set_request($OIDs{'tftpAction'},INTEGER,$Action);

  $Error = $Session->error();
  if($Error) { $Session->close(); return($Error); }

  for(my $Time = time(); time() <= $Time + $Timeout;) {
    sleep(1);
    my $Result = $Session->get_request($OIDs{'tftpResult'});
    my $Value  = $Result->{$OIDs{'tftpResult'}};
       $Error  = $Results{$Value};
    $Timeout++ if($Error eq 'inProgress');
    last       if($Error eq 'success');
  }
  $Session->close();
  return($Error);
}

Being held on hold is a familiar customer experience today. After all, on a free call you may push the phone’s speaker button and try to relax or do something useful with your time. And sometimes, after a few minutes, you find yourself caught by a nagging and senseless piece of waiting loop music. They got you, if it still loops in your brain when you go to sleep.

Download MP3 (~3.74MB)

Last year a friend of mine called me for assistance with his „new“ speaker set that he had just acquired second-hand from an unknown guy. In fact, the friend had placed an ad to sell his portable keyboard and then somebody called him and offered a speaker set & powered mixer in exchange that the guy would even bring in for a smooth transaction. They did the deal. A few days later the friend was taken aback by the, um, strange sounding satellite speakers and I agreed – we heard sizzling highs on the left and sizzling highs on the right but no mids anywhere, mids totally absent.

The Solton Micro-Sat 500 set consists of two passive SP104 satellites (100W RMS/200W Peak, 4Ohms) and a passive SP515D subwoofer (500W RMS/800W Peak, 2x4Ohms) with integrated crossover and it sold for 2350,- Deutschmarks (approx. 1150,- Euro) list price in the late 1990s. Solton recommended their 10 channel powered mixer ACS10/500 to be bundled with the Micro-Sat 500, and this is what my friend got instead of cash.

After removing the grills I saw two shiny 8″ mid-range chassis and a ¾“ tweeter per satellite. Would you think that one of these 8 inchers was dead? Maybe. Would you imagine that all four were dead? Not really. The tweeter is labeled Craaft F1 and reminds me of a popular Foster-Culver / Fostex driver that I think to have seen before on Dynacord, Hughes & Kettner, LEM and other speakers. This is a good one, probably the most expensive part of the SP104.

Using wood screws instead of drive-in-nuts for grills and speakers is not a good decision. And what about the prototype-style crossover with parts glued on a wood plate instead of PCB mounting? Would be a real fun to repair this thing. And, by the way, the 8 inchers look like bottom-of-the-line steel chassis („organ speakers“), yet adequate but with a slight cheapo appeal.

At the beginning I wouldn’t have believed that all four mid-range chassis are dead, but in fact they were. So I took out the cutter and became a speaker investigator. Three chassis had a broken coil wire right at that point where the wire is guided out from coil to cone and where coil and cone and suspension are glued together. Usually, at this critical joint, the wire is coated with laquer or glue to prevent it from mechanical stress due to vibrations. It seems that this protection has failed in the course of time and then the wire got thinner and thinner until it burned out. My assumption would be that this is a defect of fabrication.

The fourth chassis obviously has been grilled by overload; think of a musician on stage who tries to get audible mid-range sound from the only one left of once four mid-range speakers.

When I contacted Solton they quickly responded with the address of a service technician who sent me four genuine replacement chassis for about 120,- Euro including VAT and shipping, which is a very fair price in my opinion. The replacement chassis had labels on their back revealing that these are TVM (Tesla) ARO 6608 speakers from Czech Republic. Using Google Cache I found out that they once retailed at 229,- Kc per piece (approx. 8,- Euro as to date of this article).