Duck's Tech Blog

FreeBSD/FreeNAS arp multicast spam

by on Dec.24, 2014, under How-To Guides, IT Issues

So, my FreeNAS Server started randomly spewing my log file with this:

Dec 24 16:16:10 zoe kernel: arp: 43:05:43:05:00:00 is multicast
Dec 24 16:16:10 zoe kernel: arp: 43:05:43:05:00:00 is multicast
Dec 24 16:16:10 zoe kernel: arp: 43:05:43:05:00:00 is multicast

It was going at a rate of about 1 a second (in bursts of 5 every 10 seconds or so).
I fired up Wireshark to work out what it was, turns out it was my OpenMesh Wifi Access points sending these packets out.

I contacted the OpenMesh guys to see what they were all about, here’s the response I got from them:

Those ARP packets are part of normal usage, our nodes use those packets as part of the mesh connectivity, used mainly to track and remove possible loops from the mesh, but also to determine mesh speeds and connectivity.

Okay, no worries, not going to get my spamming problem fixed there 😛

So, more searching around. A few forums, some complaining about arp spam, a few patches (if you compile your own kernel) and a supposed ipfw fix that I couldn’t get to work.

The option I picked that worked was to just enable multicast ARP packets. It doesn’t feel like the best option, however it was the only one I could get to work. To do this, run this as root on your FreeNAS box:

Boom, no more spam. Joy 😀

If anyone has a better solution to this (or how to make ipfw actually block it properly), let me know in the comments below 🙂


EDIT: Because I didn’t even think about it, sysctl settings are reset on boot.
You’ll need to go to System -> Tunables -> Add Tunable and enter the following in:
Value: 1
Type: sysctl
Comment: Allow Multicast to stop spam
Screen Shot 2014-12-30 at 3.09.56 pm

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3D Printing with Minecraft

by on Nov.10, 2014, under Uncategorized

My school got loaned a 3D Printer to borrow for a few weeks, now we’ve got a minecraft club. I figured I could combine the two!
The cool thing with being able to export Minecraft to a 3D Printer is that children can do it really easily without having to learn a 3D Design program.

I’ve done a bit with 3D Printing before, I bought myself a PrintrBot Plus when the Kickstarter for it was on, however I could never get my prints to work very well. I ended up giving the printer to some friends and decided that 3D Printing wasn’t for me. That was until my school got loaned an UP Mini 3D Printer. I did a test print and it just worked. Glorious.
The version of Minecraft we’re using at school here is called MinecraftEdu. It’s built for schools and gives you greater control over students (and cheaper licences).
(continue reading…)

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Fixing a Barcode Reader Trigger

by on Jun.21, 2014, under Home, How-To Guides, School

A few years ago I bought a barcode reader for use in a school Library. It was a Cino 780BT, Bluetooth, nice base station, glorious battery. It was a really nice unit.
One slight issue: The trigger switch on them sucks.  The first one we warrantied and got a replacement, the second one developed the same fault after a year or so of use too. The first time it happened the switch had come loose from the board, so I resoldered it back on (it’s a SMD switch, so there wasn’t much holding it on).
I contacted the company, they wanted me to send it back to them to fix (and charge me for it), the switch would be $20 + labour to fit it. I figured since it was out of warranty I’d give it a shot and see if I could replace it.

I couldn’t find a decent switch to fit (I tried to repurpose a switch from a mouse, but I couldn’t get it to fit right), so I used a switch from my Mechanical Keyboard sampler kit (it has 4 different types of switches to try out to see which one you like).

So: Little bit of soldering and some hot glue later, I have a working barcode reader again!IMG_1432

Read More to see some in progress pictures!

(continue reading…)

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Traffic Logging with Asus RT-N56U

by on Dec.31, 2013, under Home, How-To Guides

UPDATES! 21/6/14: Use a different interface that does just WAN traffic and made the cron thing actually work. Scroll down for the green bits (padavans firmware only though).

I’ve spent the last few days fiddling around with network traffic monitoring on my modem so I can track downloads for each different computer on my network. This article is a how to guide and a set of notes about getting it working.
If you want to follow this guide, you will need an Asus RT-N56U or one of the similar models. You can also mostly follow this guide using any OpenWRT routers (but you will need to adjust as you go to suit your router). I initially set it up using the stock firmware on the RT-N56U, however I ran into issues where it was reporting the wrong amount of traffic. After I installed the Padavan’s Firmware, I still had the same problem (I later solved it by disabling hardware NAT below). In theory this technique should work with the stock firmware and I’ll detail it below as well as how to get Padavan’s Firmware up and running too.

The final result of this is to be able to see a screen like this:
Screen Shot 2013-12-31 at 11.49.33 am

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MacBook Pro Retina Going to Sleep on Battery in Mavericks

by on Dec.30, 2013, under Home, How-To Guides, IT Issues

I recently got myself a MacBook Pro 15″ Retina and noticed that in Mavericks they have removed the option to have separate timers for display sleep and computer sleep.  You can turn off sleep mode  when you’re running on AC power, but not when you’re running on the battery.

The problem with this is that I want the display to turn off to save battery power, but I want all my background processes (eg. Adium/Colloquy) to continue running and for it to stay connected to wifi, but when the display goes blank, it goes straight to sleep and disconnects everything!

The fix for this is to manually set the options via pmset in the terminal. To do this, you’ll need to do the following:
1.    Open Terminal (it’s in the Utilities folder under Applications)
2.    Enter the command:  sudo pmset -b sleep 0
3.    Enter the command:  sudo pmset -b standby 0

You will need to enter your password after running these commands (if it asks for it).
For more information about what this command does, check here:

Hope this helps someone 🙂


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How to throttle Skype so it doesn’t use so much bandwidth.

by on Nov.05, 2013, under Home, How-To Guides

I’ve done this as both a Mac and PC guide, the PC way of doing it is actually a little easier (but I use a paid program for it).
I’m on a 100mbit connection with a 720p iSight camera on my MacBook, so it uses about 500KiB/s of uploads (+ whatever the person I’m talking to is sending me back) which turns out to be something like 2gb an hour. This being said, Skype runs just fine on 50-100KiB/s.
When you turn on the speed cap thing, give it a minute or so and Skype will automatically adjust the video quality to suit the bandwidth available to it, so set your limit, then chill for a bit and see if you’re getting the quality you want

You’ll need a program called Entonnoir (it’s a free one).
Download it, and pop it in your Applications folder.
In Skype, go to Preferences and check the port number under the advanced tab.

Screen Shot 2013-11-05 at 9.05.15 am

Now, in Entonnoir, hit the + button, set the port number to the same as the one in your Skype Prefs and set your limits.

Screen Shot 2013-11-05 at 9.05.39 am

I use a program called NetLimiter. It is glorious and I use it a lot for scheduling downloads (like game downloads through Origin/Steam where there’s no scheduling function built in) to run during off-peak download times.
Simply open up NetLimiter, tick the button next to Skype and enter a limit in.
If you know of a free equivalent for NetLimiter, post it in the comments!

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How to Find Good Torrents

by on Jun.19, 2013, under Uncategorized

How Torrents Work

To download a torrent you need a client (ie. uTorrent) and a tracker (ie. The tracker is simply a website that contains links to .torrent files (or the newer magnet links), these are very small files that tell your torrent client where to get the pieces of the file from.
Torrents are known as Peer to Peer (P2P), this means that you are downloading the files off other users (and not off one big server). The tracker serves to link all the users together and doesn’t actually contain any of the files.
Something to note: If a movie has only just hit the cinemas, you won’t always be able to find a good quality version of it (it will probably be mainly CAM/TS rips which aren’t worth downloading).

When searching for a torrent to download, you need to keep in mind a number of things such as how many seeders/leechers there are, comments about the torrent, whether the torrent has been uploaded by a VIP or Trusted Uploader and also the name of the torrent will give you a lot of clues as to what is in it.

VIP/Trusted Uploaders

This differs depending on what tracker you’re using, some torrent sites only allow Trusted Users to upload (these are generally private ones) and other sites can have a lot of untrusted users uploading things like viruses and fakes.  If a file has been uploaded by a Trusted User, you can safely assume that the torrent is a good one (though you should still check the other things as well such as the name of the torrent).
To see if a torrent has been uploaded by a trusted user, you will see a marker on the torrent, for example with, you will see a little skull icon.

Torrent Naming

Torrent names are made up the name of the thing you’re downloading as well as a bunch of words to indicate the quality and the group that released it.
These examples are for movies or TV shows, but most other downloads will be similar.
They start with the name of the show, followed by the Season or Episode if it’s a TV show, or the Year if it’s a movie. The season is usually in the format S01E02 (aka. Season 1, Episode 2).
After this they will have the Source of the video, here are a few common ones:
HDTV/PDTV = Ripped straight from the TV, you may notice a TV logo in the corner and sometimes the silly popover ads that you get when you’re normally watching TV.
DVDRip = Ripped straight off a DVD, generally average to good quality.
BDRip = Ripped off a BluRay, very good quality.
WebRip = Ripped off a website, ie. Downloaded from iTunes or another video streaming service.
CAM/TS = Recorded in the Cinema with a camera, avoid these, they’re usually really horrible.
R5/R6 = These are DVD’s obtained by the movie company converting the film from the source onto a DVD, it is generally before any sort of processing is put on it, so quality is comparable to a Screener and a bit less than a DVDRip.
After the source is the format it is in here some of the common ones:
720p/1080p = These are high definition, usually the size of these will be greater and normally only comes from a BDRip or a WebRip.
x264 = A video codec, this is usually used for high definition footage.
XVid = An older video codec, a lot of non-high definition footage uses this.
At the end of the file name will be the release group. For the most case this doesn’t matter, though if you’re getting a series, it’s usually good to get the whole series by the same release group so the quality is the same throughout the whole lot (but really, it doesn’t matter).

Here are a few examples:
Packed To The Rafters S06E07 PDTV x264-FUtV
So you can see that this is Packed to the Rafters, Season 6, Episode 7. It has been ripped off PDTV (Pure Digital TV, aka it’s a rip straight off the TV), it is in x264 format and the group that released it is FUtV (for most people, this doesn’t matter, however some release groups you may see around often and know that they’re a good copy).

Kath And Kimderella 2012 1080p BluRay x264-PFa
Kath and Kimderella, the movie was released in 2012, it is a 1080p high definition copy taken from a BluRay and it is in x264 format. It was released by the group PFa.



When downloading a file from BitTorrent, you connect yourself to a swarm of people who either have the file you want, or are currently downloading the file you want. The people who have the file downloaded 100% are called Seeds, and people who are still downloading the file are called Leechers. For torrents to work properly, you need seeders.
The torrent download is split into chunks, as you download chunks that make up the file, you will also seed (upload) them to the other Leechers. Even when you have finished downloading the file, it will continue to do this (so you become a Seeder instead of a Leecher). Common curtesy says you should seed the files you download to a ratio of 1 (this means you have uploaded as much as you have downloaded). Some torrent trackers (websites) will enforce a minimum ratio for your downloads, so you must seed them to a particular ratio or risk being banned from the site.

File Size

You should keep in mind how big the file is before you download it, a full 1-2 hour movie can be anywhere from 300mb (really poor quality) to 10-20gb (really high quality).  Typically an xvid/DVD Rip will be 700mb to 1.2gb, a 720p will will be 3-8gb and a 1080p rip will be 7-20gb.


Still not sure about a torrent? Go have a look at the comments with it, if it’s a fake, there *should* be a bunch of comments stating this.

Nuked/Repack Torrents

If a torrent has been nuked, it means that there was something wrong with it. The problem can vary from major problems like missing footage or audio out of sync to simple things like being named incorrectly, glitching out for 1/2 second or so.  Usually when a torrent gets nuked, there’s what’s called a repack or a proper. A repack is a fixed version of the torrent and will usually have REPACK or PROPER in the title.

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Measuring Area on a Map with Photoshop

by on Aug.15, 2012, under Home, How-To Guides

Here’s a quick guide I wrote on how to use Photoshop to easily measure an area on a Map using Photoshop.

In this guide I’m using Photoshop CS5 for Mac, most of the concepts will be similar for the other versions.
First up: Scan your map and get it into Photoshop

Working out the Scale

1. If you’ve got a scale marker on your map, use that, otherwise you’ll need to measure a distance that you know, in this case I used a basketball court (marked as 20mx33m).
2. Use the Ruler Tool in Photoshop (hidden under the eyedropper tool) and select the distance for your scale.

3. In the ruler tool options (top of the screen usually), make sure “Use Measurement Scale” is unticked. Then look at the L1 value. Write this number down!

4. In my example I got the value 246.88px. So from this we can work out that there’s 246.88 pixels in 20 meters.
This gives us 12.344 pixels per meter and if we square it we get 152.374px per square meter.

Highlighting the Area

1. Make a new layer, and using a wonderful bright colour, paint over the area you want to calculate the size of. Make sure you set the brush to have a hardness of 100%.

2. Use the Magic Wand Selection Tool to select the area you just painted. Set the tolerance to 1 and untick Antialias and Contiguous (it should select everything you’ve painted).
3. Go to the Window Menu and bring up the Histogram. If it doesn’t have the numbers underneath it, click the drop down box in the top right hand corner of it and go to Expanded View.

4. Change the “Source” dropdown box in the Histogram window to Selected Layer and write down the number under Pixels. I got 157,529px.

Doing the math

So we know that one square meter is 152.374px and our selected area is 157,529px.
So we do some quick division: 157529/152.374 and we get 1033.83meters^2

If you used this or have any corrections, please leave a comment 🙂

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Papercrafting with Aluminium

by on Jul.11, 2012, under Home, How-To Guides

Papercrafting with aluminium cans

I wanted to see if papercrafting was possible using aluminium cans (ie. Coke cans), I did a bit of a google around and there doesn’t seem to be a lot of information on the subject, so I figured I’d do some research and try a few techniques out to see what I could come up with.  I’ve split this into sections to make it a little easier to read.
If you’ve never made anything out of papercraft before, I suggest you look elsewhere Papercraft Museum and make something out of paper, it takes a significant amount of more effort (and time) to work with aluminium.

Flattening the Cans

First up, I used a knife to cut the top and bottom off the can (you can use scissors, but you’ll need to use a knife to get a start to it) and then using scissors to chop the cans into a piece I can flatten. After you’ve cut them into sheets like that, neaten the edges by using a pair of scissors to cut them straight and make sure there’s no little sharp bits.
The method for flattening the cans that I’ve found works best is to use a sandwich maker (an old one, don’t ruin your good sandwich maker!!). Before turning it on, lay down a piece of baking paper on the bottom, put about 4 cans in, then add another layer of baking paper on the top (this should help prevent at least a little bit of damage to the sandwich maker).
Hold the cans down flat as you close the lid, once you’ve done that, turn the sandwich maker on.
I haven’t fully experimented with getting the best efficiency here, but I left it on for 10 minutes with 4 cans in there, then turned it off and let it cool before I opened it.
Taadaa! Flat cans!
Other methods I have tried are:
* Ironing (Does nothing)
* Ironing and bending at the same time. This method works, but you end up with your piece looking a little bit bent as it’s hard to get it as flat as you would in a sandwich maker.
* Clamping it between 2 pieces of wood. This does absolutely nothing, if you leave it for a day or a week, they bend right back to their natural shape.
It seems like heat is very important in getting these things to stay flat.

Cutting the Sheets

I printed my design out on paper first, cut the paper version out then used it to trace onto the sheet. You may end up with pieces that’re bigger than the can, so you’ll have to deal with this by splitting it into 2 pieces.
Also, because the cans are way thicker than paper, you’ll end up with parts that will fall short because the thickness of the paper messes it up. I just dealt with it as I went and it may have resulted in a less than perfect final product, the design would probably have to be altered to give a bit of room in some corners to account for the extra thickness.
Using a knife is practically useless, you just can’t drag a knife through aluminium like you can through paper.
Scissors on the other hand are brilliant, it’s just like cutting through paper. The only issue is the end of the scissors can cause the aluminium to bend a bit. To counter this, I use a knife to piece the corners, then use the scissors to cut up to them. It’s not perfect but does the trick nicely.
You should also score the pieces using whatever you normally use to score, I use a thing that’s a bit like a needle on the end of a knife handle.
Folding is pretty simple, just do as you normally do. Be careful about bending too much though, as the metal will weaken the more you bend it!


This part is rather difficult, I tried a whole bunch of glues to work out how to get it to stick properly, I ended up settling on Contact Cement. (Contact Cement is the sort that you apply to both surfaces, let sit for ~20minutes then push them together).
This part is going to take the majority of your time, I suggest you glue 1-2 pieces at a time, put the contact cement on them, let them sit the full 20 minutes, then push together (hold for ~10 seconds or so to make sure it’s solid) before moving onto gluing 2 more pieces. Get a movie out, play some games… It’ll take a while.
The contact cement wasn’t the greatest however, as if the metal is trying to flex against the glue, it’ll pull itself apart unless you sit there holding it for at least 30 seconds, even then it doesn’t feel as strong as one would hope.
I didn’t end up trying Epoxy however, so that would be a good thing to experiment with.
Other glues I tried:
* Aleene’s Original Tacky Glue (the metal surface was too shiny for the glue to stick once it dried). This is the glue of Papercrafting gods that I had to import from the US to Australia. It’s very similar to PVA/Wood Glue, just slightly tackier making it awesome for papercraft. Just not for… Aluminiumcraft 😛
* “Hobby Cement” – Same deal as the Tacky Glue above
* Bostik Multi Bond – Same deal as above, it just can’t stick to the metal as well as it should.


And here’s my end result! Would I do it again? Nope, it took me about 3 days to get the whole thing done when the paper version took closer to a couple hours….

The design I got from: Tenpepakura Translated
And thanks to: Build Totodile  for showing me where to get it 😀

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Scanning into Microsoft Office 2010

by on Apr.30, 2012, under How-To Guides

So it appears that Microsoft removed the ability to scan directly into a document in Office 2007.

It’s a pretty silly move I suppose, so I tried to work out a way to bring the functionality back, first of all, here’s how Microsoft suggests you should do it:
Step 1: Use the software that was included with your scanner to scan and save the image to your computer.

… Yeah, no thanks.

Here’s two actual solutions to the problem:

Option 1: Using a Key Combo

Install your scanner drivers as per normal.
In Word, press the alt key and type ips (note: don’t hold them down or it won’t work, just type out ips).

Word will then pop up asking you what scanner you want to use. It didn’t bring up the scanner interface on the machine I was working with, it just went right ahead and scanned the whole document, so this may not be the best solution for some. Note that the next solution is more difficult and does exactly the same thing as this one.

Source: Comments on this page:

Option 2: Creating a button on the Ribbon

This option is a lot more complicated, make sure you get all the steps right and in order! When you’re done you’ll have a button on your Insert tab of the Ribbon.

  1. Open Word and go to the View Tab then click on Macros.
  2. Give the macro a name (eg. Scan)
  3. Enter the following text EXACTLY:  Application.WordBasic.InsertImagerScan
  4. Save and Close the Window
  5. Right click anywhere on the Ribbon and Select “Customise the Ribbon”
  6. On the right hand pane, click on the Insert category and click New Group.
  7. Rename the Group to anything you like (eg. Scan)
  8. On the Left Hand Pane, Change the drop down box at the top to Macros then select the Macro you made in step 2-4 and click the Add button (so it appears underneath the scan group you made in Step 6.
  9. Rename it to something better like “Scan Document” and pick a pretty picture for it.
  10. Click Okay and you’re done!

Now you can just click the button to Scan a document. It’s exactly the same as the alt-ips option above though, but might be easier for people to remember so they can click the button.


If this helped you, please leave a comment to say thanks 😀


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