Clock Part 3

I finally finished the outer case of my clock. Only 19 layers of 3mm acrylic stacked on top of each other.

Laser cutting the rear panel and finger slot
red perspex box with clock electronics showing, rear lid off
Rear panel with finger slot and barrel jack holder
rear panel of clock with wire going into the finger slot
Barrel Jack inside the finger slot

I built a finger slot into the back of the clock so it’s easier to carry, but also to house the barrel jack for mounting the clock flush to the wall, allowong me to hide the power cord in the wall (oneday)

pile of acrylic sheets neetly lined up
This is the pile of acrylic I had to cut out of the inside of the clock.

That pile on the left was cut out to make the cavity in the case.


Launch emacs from cygwin

I have written about about using emacs in cygwin and how to launch emacs from cygwin, but I had some problems with the batch file approach in that emacs’ path differ from bash’s. Then ack fails to work from within emacs which makes me sad.

After googling around a bit, I saw a few suggestion that trie to fix the path in emacs, but I think a better approach is to launch emacs from within bash so it inherits the bash environment.

Here is my attempt using vbscript:

Save that script somewhere and then make a Windows Shortcut to it but incle the wscript.exe in the target:

You can then launch it from the Start Menu in Windows 7.

I wrote to Turnbull to complain about the lack of NBN. Here is his reply

After traveling to New Zealand for #lca2015 and experiencing fibre to the home at my friends house, I decided to write to Malcolm Turnbull to express my concern about the slow rollout of the NBN in Australia.

He actually personally replied directly to my email only 4 hours later. In the interest of openness I am putting the whole email below. I have rearranged it to fix the topposting.

The tl;dr is “It’s all Labor’s fault”

My email to Mal. (I think we can say we are on first name terms now)

From: Jason Lewis
Sent: Tuesday, 20 January 2015 1:52 PM
To: Turnbull, Malcolm (MP)
Subject: NBN Roll-out

Dear Mr Turnbull,

I’m writing to express my concern with the woefully slow roll-out of the

I’ve recently been travelling in other countries where fibre to the home
is already commonplace and it makes the Australian broadband offering
feel terribly inadequate.

I feel this will lead to a further reduction in Australia’s
international competitiveness.

Please devote more resources to speeding up the roll-out.



And his response:

Dear Jason,

Thanks for your candid comments.

Unfortunately Labor significantly underestimated the cost and complexity of this project and, as a result, released rollout schedules that were unrealistic and inaccurate.

For instance, Labor originally forecast that 2.7 million houses would be passed by fibre by 30 June 2014. In NBN Co’s last Corporate Plan released in August 2012, it was revised to 1.3 million houses passed by fibre. The comprehensive Strategic Review completed in December 2013 however, found that the NBN would only pass 467,000 houses with fibre by 30 June 2014. The actual number reached by 1 July 2014 was 492,000 premises – less than one-fifth of the original target.

I highlighted the problems which Labor created with their false rollout expectations in a recent blog available here:

In addition, the Government recently undertook a Broadband Availability and Quality Report, which found that there are more than 1.6 million premises across Australia with very poor or no fixed broadband access at all. However, Labor made no effort to prioritise these areas in their rollout.

The Government has instructed NBN Co to revise its current rollout schedule to meet three key objectives:

  1. To ensure that the underserved areas in Australia are prioritised in the NBN Co rollout. On average, areas with very poor broadband will receive upgrades two years sooner.
  2. To ensure that the NBN upgrades are delivered sooner and more affordably, by using a mix of technologies. The Strategic Review found that under the model adopted by the Coalition, the project will be finished four years sooner than would have otherwise been the case.
  3. To ensure that information provided in the public domain is accurate and can be relied upon by businesses and households waiting for broadband upgrades.

The fact is that the NBN, up to the election, had reached only three per cent of Australian premises after four years and $6.4 billion of funding.

NBN Co is now determining which technologies are most cost effective and should be utilised on an area-by-area basis so as to minimise peak funding, optimise economic returns and deliver broadband upgrades sooner. This is highly demanding and complex work which involves renegotiating deals with Telstra and Optus to take over portions of their fixed line networks. Naturally this is taking time to complete.

In the meantime, NBN Co has continued to expand its fibre network in areas where construction contracts had been signed at the time of the election. Across the country, more than 500,000 premises have been passed by NBN fibre and work is underway to extend the network to reach a further 600,000 premises.

Sites that are not currently represented on the NBN Co maps are being reviewed in line with rollout priorities. Importantly, the network will continue to be built on a state-of-the-art platform, but will use existing infrastructure where it makes sense to do so. In areas where work has not commenced, NBN Co will be making decisions about construction on the basis of review findings. NBN Co is significantly advanced in planning the multi-technology mix and rollout plans will be publicly released once they are completed. More information about the NBN rollout will be published by NBN Co on its website when it is available.

You may also be interested to know that the Government has secured the progressive transfer of the necessary parts of Telstra’s copper and HFC (pay TV) cable networks to NBN Co at no additional expense. Telstra’s 1.4 million shareholders have been ‘kept whole’ in keeping with the Government’s pre-election commitment.
These agreements are a key milestone in shifting the NBN to the Multi Technology Mix the company has determined is its optimal strategy. The December 2013 Strategic Review found the shift to a multi-technology NBN will reduce its cost by $30 billion, and save at least four years in construction time.
Importantly, under these agreements, NBN Co will make use of Telstra’s copper and HFC networks (i.e. the network used to deliver pay television) rather than decommissioning and wasting these assets, as Labor had planned.

Yours sincerely,

Malcolm Turnbull

I just donated to Wikipedia

After reading a blog post from someone who donated to Wikipedia because they use it a lot, I realised I use it a lot too, so I decided to donate too. Unfortunately I can’t quite remember who’s post it was, but thank you whoever you are!

I donated $30. You should too if you like Wikipedia, and you use it.

Apache [warn] RSA server certificate CommonName (CN) does NOT match server name!?

Apache was giving me lots of errors like this on my host that has multiple virtual hosts on it.

After a little investigation it turned out the CN in the certificate was set to www.domain but the vhost’s ServerName was set to www-less.

The solution turned out to be to ensure the vhost ServerName == the CN in the certificate. You can examine certificate with:

And in the vhost, make sure there is a ServerAlias for the www-less version:

a few less warnings in the logs now. Phew!

Using fail2ban to mitigate WordPress xmlrpc.php DDoS attacks

The other day my WordPress network went down. Upon investigation it turned out it was receiving a massive amount of http posts to the xmlrpc.php file. Apparently there is a WordPress DDoS that uses this mechanism. It brings apache and mysql to their knees as they can’t process the posts fast enough. If you search google for WordPress xmlrpc.php DDoS you can find lot more info about this.

An temporary fix is to block all access to that file from your apache configs with something like:

That brought the load back to normal so I could at least access the WordPress backend.

After googling around for a solution it appeared that fail2ban could help. Luckily there is a plugin for that. WP fail2ban has two parts. The first is a plugin that enables logging of xmlrpc events and authentication events to /var/log/auth. It is important to keep these events separate from the normal http access logs as the access log file can get very large and fail2ban can raise the load significantly just processing it.

You also need to add a few configuration options to wp-config.php

See the readme for more details about what they do

The second part is enabling filters and gaols in fail2ban. Luckily this is also provided by the WP fail2ban plugin. Copy the wordpress.conf file from the wp-fail2ban directory to the fail2ban config directory:

Then edit /etc/jail.local and insert:

Now restart fail2ban:

Remove the block on the xmlrpc.php file from your apache config and restart apache. Then you should see in your fail2ban logs something like:

I found however that I was being hit from over 1800 unique IP addresses and despite fail2ban successfully banning them, it was taking too long to ban enough that the load would return to normal so I re-blocked the xmlrpc.php file for 24 hours. After that, I enabled it and it seemed as though the DDoS had gone away. So far so good.

Howto quickly find your Beaglebone Black’s IP address

Whenever I connect my Beaglebone Black (BBB) to a network, I have to work out it’s IP address so I can ssh into it. This can be tricky. Some of your options are:

  1. connect to the serial terminal, or connect over the usb network interface which gives the BBB the address, log in and issue the command ip addr.
  2. use nmap to try and search out its IP address on your subnet but this is time consuming and not very accurate I have found.
  3. use avahi-browse -rat (thanks Madox for that tip.)

Last night I came up with a Better Way™. Rather than trying to determine the BBB’s address, why not use a fully qualified domain name and a dynamic dns service? I could then just type ssh or whatever and log in. Think how that would simplify one’s life!

To implement this, set up a dynamic DNS somewhere with a FQDN for your BBB. If you happen to have your own domain name already you can use a sub-domain from that. I think its fairly common for DNS hosts to offer an API to update your IP address. I happen to use Rimu Hosting and they have their own simple web api.

Then you just need to write a little script to update the IP address every time the DHCP client receives a new IP address, and drop it into /etc/dhcp/dhclient-exit-hooks.d/

Here is my script. This will only work with Rimu Hosting as they have their own privately developed API, and you’d need to insert your own KEY into the script.


I discovered this didn’t work at home. Turns out that dnsmasq in OpenWRT is set to ignore this kind of dns request, due to potential security risks. There is a solution to that. Add a list rebind_domain line to your /etc/config/dhcp line on the router.

Thanks to Michal Čihař for the solution to that.

Facebook selecting wrong thumbnail for WordPress links

Does Facebook keep selecting the wrong thumbnail for WordPress links for you? The solution is to give Facebook some extra instruction about what image to use for the thumbnail, using open graph.

If you use a static frontpage, it’s a simple matter of adding something like:

<meta property="og:image" content="" />

to the Full meta tags of your front page.

You can check what facebook will do with your site by using their link debugger:

WordPress >= 3.9.1 seems to do the right thing for posts according to my testing.