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:
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).
SSH Host Keys
The SSH client needs to be configured to check these records. Specifying "
To determine the name of the record to use, convert your email address into a domain name by replacing the ampersand with a dot1. To publish your entire public key, run the tool as follows.
The first parameter specifies the file containing your public key in binary format, and the second parameter specifies the domain name to use. To publish a reference to your public key, run the tool as follows.
The first parameter specifies the fingerprint of your key, and the second parameter the URL at which the public key can be found. It is also possible to only publish the fingerprint or only the URL. Simply add the record which the tool outputs to your zone file2.
There is also another method to publish GPG keys called PKA. The only documentation I can find is a specification in German linked from the blog post mentioned above. I still managed to set it up though. This method uses a
This specifies the fingerprint and URL, just as with the second
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.
The client configuration is also very similar. It simply needs to enable TCP connections, set the correct port number, and specify the proxy server.
OpenVPN can also authenticate to the proxy server using either Basic or NTLM authentication. To enable this add "
For my Masters project I need a method by which the user can specify which functions should be run on an SPE1. This method should be simple, clear and easy to turn on and off. I stumbled upon a blog post a little while ago (I think it was this one) which explained decorators in Python, which is the perfect tool for the job. Decorators are used to transform functions, but without changing the function itself or the calls to it.
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.
I don't watch very many TV series at all. I have watched all the House episodes, which I think are absolutely fantastic. It is a show I enjoy immensely and which is simply awesome. (If you haven't seen House I can strongly recommend it.) I then watched the first season of Heroes, but lost interest partway through the second season. (I found it too disjointed and drawn out.)
The only other series I have enjoyed is CSI. I have watched entire seasons of all three sub-series (Las Vegas, Miami and New York) and have always enjoyed them. The reasons I like it are as follows.
However, I have just finished watching the eighth season of CSI Las Vegas, and I am very disappointed with the show. It has continually been breaking points 1 and 3 above, two of the prime reasons that I liked it so much. There have been (significant) recurring stories throughout the season, and the main characters have become personally involved in the cases, which has caused me to take it very seriously.
This has taken the enjoyment out of it for me, and since I watch movies and series to relax and unwind2 it's no longer worth my while to watch CSI. I will continue to watch previous seasons, but I probably won't continue with future Las Vegas seasons.
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.
Since there is no Ubuntu package for Drupal 6, I created my own package based
Clean URLs allows one to have URLs like
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
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
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.
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.
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.
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 documents are advertised with a
The former method can be accomplished with the
The following lines in
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.
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.
I have been using Gmail for a while now, and really think that it's about the best email provider out there. I recently moved my mail over from Google Apps to my own server, but I wanted the major features that I liked. I've always used a desktop mail client and used POP3 and SMTP to receive and send mail.
These are the features I particularly like:
To automatically store sent messages on the server, I used Postfix's
To make POP3 access independent from IMAP, I first configured Dovecot to use a different mail location for each as follows.
I then used the following Procmail recipe to send incoming messages to both locations.
At the moment this is only setup for my user, but it should be possible to do it for all users by creating a global
As most people know, email is horribly insecure. It is trivial to forge the
Unfortunately all of these schemes have problems due to the fact that they are an addition to the existing mail system. SPF and SenderID prevent plain forwarding (requiring additional schemes like SRS or whitelisting of forwarders), and MTAs and mailing lists which modify messages break DomainKey and DKIM signatures. Despite these issues, email forgery is an issue which needs to be addressed, and we cannot wait for a perfect solution before adopting it. Some major mail providers (including Gmail and Yahoo) are already implementing these schemes.
I have therefore configured SPF and DKIM in my Postfix mail setup. My SPF policy allows mail from my server and SOFTFAILs all other hosts, and all outgoing mail is signed with DKIM. Incoming mail is checked for SPF and DKIM, but aren't discared even if the checks fail. I will be keeping an eye on things and will revise my policy when I think it safe.
To create an SPF policy, add a TXT record to your DNS records according to the SPF syntax. The policy should authorise all hosts from which you send mail. (Mine simply authorises my mail server since I send all mail through it.) You also need a policy for the hostname presented by your mail server in its HELO/EHLO command. You should also create policies for all subdomains which aren't used for mail.
To check SPF records for incoming mail, I used the SPF policy daemon for Postfix. It is packaged for Ubuntu as
To sign and check DKIM I use DKIMproxy. There isn't an Ubuntu package so I installed it from source. The instructions on the site are good, and include details for Postfix. You will need to generate a key to sign with and publish it in DNS, and then configure Postfix to sign outgoing messages and validate incoming messages. DKIMproxy won't discard messages with invalid signatures by default.
DKIM includes a component called ADSP which allows domains to publish their signing policy. The strongest policy states that all messages are signed with DKIM and any messages without signatures should be discarded. This will allow mail servers to reject messages not sent through your mail server. However, the standard is not finalised yet, and issues regarding mailing lists still need to be addressed.
So, I have finally jumped on the blogging bandwagon. I'm not quite sure that it's the wagon for me, but I'll give it a try anyway. Most of the content will be fairly technical, since I'm not a pour-your-heart-out type of guy. A lot of it will be about things I setup on Linux, occasionally some code which I've written, and possibly some stuff about my Masters project.