Vodacom4me and MyMTN allow you to send free SMSs from a computer. Unfortunately those sites are not accessible from a cellphone. I came across a site which provides a mobile interface for Vodacom4me and MyMTN¹. This means that you can send SMSs from your cellphone for the cost of the GPRS/UMTS data required to access the site. I having been using this for quite a while, and it works fairly well.

However, there are a few aspects of the site which I don't like, and so I wrote my own version which performs the same function with the following extra features:

1. Uses cookies to store login data instead of a URL with parameters which needs to be bookmarked (although it will fall back to this method if the user agent doesn't support cookies).
2. Submits forms using POST instead of GET (but will fall back to GET if the user agent doesn't support POST).
3. Allows multiple recipients (although only Vodacom4me supports this).
4. Specifies the maximum message length in the textarea so that phones which support it can show how many characters are left.²
5. Automatically logs into Vodacom4me/MyMTN again if session has expired.³
6. Cleaner, less cluttered interface (mainly optimised for my phone ;-) ).
7. Accessible over HTTPS for extra security.

The site is available at http://m.mene.za.net/ (or with HTTPS). Obviously the restrictions enforced by Vodacom4me and MyMTN still apply. Vodacom4me allows 20 SMSs per day to Vodacom numbers for Vodacom subscribers only. MyMTN allows 5 SMSs per day to MTN numbers for anyone. The source code is available for anyone who is interested (and brave enough).

I discovered that OpenVPN supports connections through an HTTP proxy server. This makes it possible to establish a VPN from a completely firewalled network where the only external access is through a proxy server¹. It takes advantage of the fact that SSL connections are simply tunnelled through the server and aren't interfered with like unencrypted connections.

The server setup is almost identical to a normal configuration, except that the tunnel must use TCP instead of UDP (since the proxy server will establish a TCP connection). Since most proxy servers only allow SSL connections to certain ports, you will also need to change the port number that the server listens on. The best is 443 since that is used for HTTPS, but if the server is also running a web server on port 443, then 563 is probably the next best choice. This port is assigned to NNTPS, and is allowed by the default Squid configuration. The following two lines enable TCP connections and change the port number.

proto tcp-server
port 563

The client configuration is also very similar. It simply needs to enable TCP connections, set the correct port number, and specify the proxy server.

remote vpn.example.com 563
http-proxy cache.saix.net 8080
proto tcp-client

OpenVPN can also authenticate to the proxy server using either Basic or NTLM authentication. To enable this add "stdin basic" or "stdin ntlm" to the http-proxy line. This will prompt for the username and password when the VPN is started. For more details see the OpenVPN documentation.

Since I might be posting entries regarding my Masters project, I thought that I would provide a brief overview of the project to put it in perspective. I am doing my MSc in Electrical Engineering at UCT as part of the ACE group headed by Prof. Inggs. The group is based at the CHPC, which is part of the Meraka Institute, which in turn is part of the CSIR. The group's research is focused on developing new platforms and methods for HPC.

My project is to investigate the suitability of the Cell processor for HPC. The Cell processor is found in the PlayStation 3 and in BladeCenters, and is a very powerful processor. It achieves this by using two different types of cores. The one type (PPU) is a general purpose core capable of running an operating system, while the other type (SPU) is designed specifically to crunch numbers.

The disadvantage of this architecture is that it is very difficult to program for. When using the IBM Cell SDK, the user needs to write separate programs for each type of core, and needs to manage the SPEs manually as well as take care of all memory transfers. This requires a good knowledge of the architecture, and results in a lengthy development process and unportable code.

For the Cell processor to be a successfull platform in HPC the development process must be made easier while still making efficient use of the Cell's capabilities. There are a number of commercial and non-commercial tools which aim to do this using a variety of methods. I have looked into these tools and have not found one which is both effective and open.

I therefore aim to create my own platform with which to program the Cell processor. The idea is to use [Python][] as the end user language, and to make a backend which transparently runs certain functions on the SPEs. This will involve converting the functions into C or C++, adding code to manage execution on an SPE and do the required memory transfers, compile it with the [GCC][] compiler and then execute it.

It is quite an ambitious plan, and there are a lot of potential pitfalls. If it succeeds however, I think that it will be a very easy way to develop for the Cell processor while still having portable code.

Seeing that I've spent countless hours setting up my Drupal installation, I thought that I would share this with others and document it for future reference. Drupal is an extremely powerful CMS which can be used to create a wide variety of sites. The disadvantage of this is that it requires a fair amount of work to setup a straightforward blog, which involves installing and configuring numerous modules.

Installation

Since there is no Ubuntu package for Drupal 6, I created my own package based on the drupal5 one. I set it up as a virtual host in Lighttpd by simply symlinking the domain name to /usr/share/drupal6. I created a MySQL database for the site and went through the Drupal install process. Since I'm using a multi-site installation, I also needed to alias the /files directory for each site.

$HTTP["host"] == "michael.gorven.za.net" {
    alias.url = ( "/files/" => "/home/mgorven/public_html/" )
}

Clean URLs

Clean URLs allows one to have URLs like /about instead of /index.php?q=about. This however requires that the web server rewrites URLs from the former to the latter. Drupal includes an htaccess file containing settings for Apache, but not for Lighttpd. Lighttpd does have a rewrite module, but it doesn't support the conditions that Drupal needs (such as checking if a file exists).

Lighttpd does however have a module which allows one to add scripts to the request process written in [Lua][]. A script has already been [developed][drupal.lua-devel] which implements the required rewriting for Drupal. The following lines in lighttpd.conf enable this for a specified site (after enabling [mod_magnet][] and downloading the [script][drupal.lua]).

$HTTP["host"] == "michael.gorven.za.net" {
    index-file.names = ( "index.php" )
    magnet.attract-physical-path-to = ( "/etc/lighttpd/drupal.lua" )
}

Blog

When Drupal is first installed, there is no mention of blogging as such. The first step is to enable the Blog core module¹. This creates a blog content type and enables a blog for each user. (The module is designed for a multi-user blog, but can be used for a single user as well.) However, this doesn't give you all the functionality you expect from a blog engine.

Tagging is handled by the Taxonomy core module. You first need to create a vocabulary though, and enable it for blog posts. (This took me ages to discover.) In order to get nice URLs (including the date and post title, for example) you need to install the [Pathauto][] module and configure a pattern for blog posts. You may also want to define a pattern for tags.

There is also no archive functionality. The best way that I can find is the [Views][] module. It includes a pre-defined "archive" view which can display posts from a specific month, and links to the monthly pages. Even after much investigation I couldn't get the archive to behave like typical blog archives (i.e. /blog/2008/07/07, /blog/2008/07 and /blog/2008 for daily, monthly and yearly archives respectively).

Other Blog Features

The [Trackback][] and [Pingback][] modules implement automatic linking with other blogs. (I haven't actually tested these yet.) The Blog API core module allows the blog to be managed with external clients. The [Markdown][markdown-mod] module allows you to write posts using [Markdown][] syntax instead of HTML.

Comments

Drupal enables comments for blog posts by default. The [Akismet][akismet-mod] module implements spam filtering using the [Akismet][] service. The [CAPTCHA][captcha-mod] and [reCAPTCHA][recaptcha-mod] modules allows you to require users to answer a [reCAPTCHA][] when submitting comments. (I haven't actually enabled [CAPTCHAs][captcha] since I haven't gotten any comment spam yet. Or real comments for that matter...)

Posting by email

The [Mailhandler][] module allows you to submit posts via email. The configuration is fairly straightforward, except for the available commands which can be found [here][commands]. These can be specified at the beginning of emails and in the configuration as defaults. I use the following commands.

type: blog
taxonomy: [mail]
promote: 1
status: 1
comment: 2

This creates blog posts and tags them with the "mail" tag. Posts are published and promoted to the front page, and comments are enabled.

The one thing it doesn't handle is attachments (such as images). There are a couple of modules² which support this, but they aren't available for Drupal 6 yet. ([Vhata][] has also hacked together a [photo blogging][phoblog] system, but this isn't implemented as a Drupal module.) I don't really need this feature, so I'm going to wait until these modules are updated.

OpenID

The [OpenID][openid-mod] module allows you to log into your site using [OpenID][]. The [OpenID URL][openidurl] module allows you to delegate your Drupal site as an OpenID by specifying your provider and/or your [Yadis][] document.

Yadis Advertisement

Yadis documents are advertised with a meta header in the HTML document, but this isn't the ideal method of doing so since the relaying party needs to download the entire HTML file. The [preferred methods][intertwingly] are to insert an X-XRDS-Location in the HTTP headers, or to automatically serve the Yadis document if the user agent specifies application/xrds+xml in the Accept header.

The former method can be accomplished with the setenv module for Lighttpd. The second is essentially a conditional rewrite, and so requires some Lua scripting again. The following script will do the job.

if lighty.request["Accept"] == "application/xrds+xml" then
    lighty.env["uri.path"] = "/files/yadis.xrdf"
end

The following lines in lighttpd.conf will announce the Yadis document for the root URL.

$HTTP["url"] == "/" {
    magnet.attract-raw-url-to = ( "/etc/lighttpd/yadis.lua" )
    setenv.add-response-header = ( "X-XRDS-Location" => "http://michael.gorven.za.net/files/yadis.xrdf" )
}

Random Stuff

The tag block is generated by the [Tagadelic][] module. The "Recent Tracks" block is generated from my [LastFM][] feed by the Aggregator core module, and the list of networks is simply a custom block. The [Atom][] feed is generated by the [Atom][atom-mod] module. The contact form, search and file upload are all core modules.

Missing Stuff

The one thing I haven't sorted out is image handling. There are a couple ways to [handle images][drupal-images] in Drupal, but none of these appeal to me (they're too complicated). I will probably just upload images as attachments and insert them manually in the body.