On Tue, 12 Mar 2013 12:28:23 +0100, Simon Quantrill wrote:

Apart from running a crontab every 5 minutes I cant think of any other
way to reliably update the dns with the clients ip address

anybody got some clues ?

Two really.
1. From what I gather your server is a dhclient which means you can
add or link a script in /etc/dhcp/dhclient-exit-hooks.d/

  1. a quick glance at 01ifupdown, shows execution of all files in
    /etc/network/if-up.d if $2 = up. I would link something like
    /etc/network/if-up.d/xx_my_stuff, which would execute last, to do
    whatever I wanted done.

Just for fun, create/link it, set owner/perms same as other files in that
directory and have the script do a

! /bin/bash

echo “————–” >> /root/results
env | sort >> /root/results

Then run the commands to bring device down/up and
cat /root/results

Spining arrows

The archers paradox best explained by this youtube video Picture speak a thousand words.. but anyhow the basic thing is this nock you arrow in your bow and depending how much of centre the bow is (how thick it is at the arrow rest) the more to the left or right your arrow is pointing. However the arrow if correctly spined for the bow will fly straight as if short form the centre, this is the paradox. When you draw the string of your bow and release it push’s from the back of the arrow causing it to bend inwards then it straightens out and bends the other way it continues vibrating until it stabilises. This effect causes the arrow to bend around the bow and shoots as though it comes from the centre line. If the spine of your arrow doest match your bow then some interesting effects can happen a stiff arrow could fly to one side instead of straightening up. I to low spine can shatter as it is being push beyond its bend radius. The standard way of measuring the deflection of arrows comes form the USA and is specifically designed for american flatbows. It uses a 2lb weight a scale and an arrow suspended 26” from each other. I built my own here very roughly The arrow is suspended between the 26inch gap and the arm is placed on to the arrow making sure you get the orientation correct you should nock across the grain so the strain from the string goes across the grain make sure the grain runs horizontal when you do this test ;) I created a very crude scale notice the use of duct tape my trade mark. the scale here is measured from the centre point using the piece of wood marked with .25” spaces between 0 and 1inch from the resting centre point of the pointer arm The centre point here being the x on the rawlplug. The scales used are the american standards for a 2lb weight between 26” and are used for american flat bows it is recommended that you spin arrows roughly the poundage of your bow at 28 inch draw. But for a longbow it is recorded that this be 2/3 of the total weight of your bow. I think the best way is to make up a few shafts of differing spine weights around the poundage of your bow and shot them with piles but no feathers. Check which ones shoot well and choose that as your spine rating for that particular bow..

Trip to Quicks

Yesterday decided to pop down and take a look in quicks archery, as I was about 25 mins down the road I thought it might be worth a look as I have had lots of long evenings looking through there catalogues.. Anyhow I popped over the quicks in waterlooville I arrived around 1:30 and found they were shut apparently there lunch time is 12’ish to 2’ish what a job ;) But that’s probably due to the bad parking around the area.. Anyhow I went in and there was a shop full of people asking questions, I took a look around and found it to be not much more than a market trader.. The catalogue is much better representation of the company.. I asked if they had a feather cutter as I really was interested but didn’t want to pay the postage and of course they didn’t have one in stock. There was no mention of ordering it or checking to look in one of the other stores.. Sorry quicks a little disappointing..

Sunday Field archery

Worlingham field archers seem to be having a rough time with the land they use for the field archery club a really nice wooded area located in worlingham. The day started at 10am I arrived around 9am to meet up with my uncle. We started off with a cup of tea and a chat about the best equipment to use I borrowed a longbow from him and a few arrows and of course the quiver used on robin hood the movie!!. I felt the part ;) I tried the quiver over the shoulder on my back and went for a practice shoot but managed to almost stab my eye out with an arrow whilst trying to get it out of the quiver decided to tie it off round the waist this felt much better and I will be making one when I get home as I found this to work really good. Especially for field archery. I started shooting the arrows from my uncle they all shot to the left I decided these where obviously to stiff and switched for lighter set. These shot much straighter however didn’t improve my score much!.. I heard 500’s and 400’s … I managed a good 53 ;) but the day was a real treat it rained hard once and lucky I listened to my dad and took his ‘pak a mak’ it saved the day. Fletchings got little bit wet but the oiled canvas quiver was able to roll over the fletchings need to make one did I mention that !!.. We had a course of 14 targets I believe it was and we went around twice, as always it was a fun walk and nice people there were three ladies and an other gent who I paired up with to shoot. I found out later that all of them were very good ;) and learned a number of tips. Now I need to get practice in for the shoot in balk….

Bow repaired

I don’t think i’ll get away with shooting in the garden although i think it is safe i think the neighbor thinks not anyhow I did some searching and it dawned on me that re-enactors use rubber blunts to shoot at each other ;) So i found on Richard Head’s website’ redheads’ I like ordering form Richard but it always costs me a fortune for the postage as im in the Netherlands I did a little more research and I found another company here in the netherlands ordered and waiting Get a redhead! I think I will be able to shoot at a can or two its not quite the same as shooting at my target but we will give it a try. I got help from Ian to stick on my new hickory backing on my bow to repair it and I got the band saw out and trimmed it down, the glue lines are a little thick but its looking nice. The nocks are glued on just need to sand it and oil it down now the glue lines will clean up so its looking prity good so far ;) Just thought i’d also post my sons bow, it’s hard maple american flat bow it pulls about 16 lbs at 17 inches and it can pump an arrow down the back garden as quick as my wife’s 38 pounder ;) ‘Oma’ said it’s not a toy and he can not use it unless we are there hehehehe oops ;) And of course these are my next arrow tests, i’m inserting hard wood here originally the hardwood was to make footed arrows but i cut the kerf in the wrong place and the wood splits bit annoying I made 15 but its good to put the wood to work. These three arrow shafts are 3/8” made with a dowel cutter and hand sanded here ill put the self nocks and then ill get around to feathers and points.. here they are waiting for the glue to dry out..

Creating arrows

One of the main issues with 3d archery as I have found is that most people lose them.. Allow I have done pretty well I don’t think I have actually ever lost an arrow!! although I have broken a few. Anyhow my point is it can get expensive to buy arrows. So the obvious way to keep up the hobby is to start making your own. When i first started I hadn’t got a clue what to get or what to do so I hope to put down some notes here to make it a little easier. There are a number of parts to an arrow. The shaft the point the nock and the feathers. All of this can be bought quite easily from the suppliers of arrows and archery equipment. I have done this up till now and the results have been fairly good. The first set of arrows I bought ready made for the bow I had at the time and they have lasted quite well. However shortly after this I wanted to make my own; so the next step was to buy the bits and stick them together. To be honest I thought a arrow was just an arrow ;) but this is not the case there are many things to take into consideration when you have arrows. Type of wood is the first choice, I was lead to believe very early on that port Orford cedar was by far the best arrow making material so I bought 12. The shafts were weighted 20-35 40-50 and so on I had a 50 pound bow so 40-50 was good (I thought) I was’t to sure about the feathers and the points so I got full size feathers a tube of glue and some 3d points. I stuck all the feathers and points on and shot them. First thing I noticed was that the arrows shot of at an angle maybe my bad archery technique, then every other arrow the points came away from the shaft I used hot melt glue.. I also noticed a cut forming on my hand and then I got a feather lodged rather deep in my finger.. Mmm I thought this arrow making business must have more to it than this!!!.. There is a saying that you can shoot well with good arrows and a bad bow but you always shoot bad with a fantastic bow and bad arrows….. So this is my research so far in to the construction of wooden arrows.. Wood: Many believe that port Orford cedar is the best for arrow shafts, probably because of this and the fact that the trees have to lye until the bark rots before the shaft produces make any there is a world shortage. Ash and birch were used during medieval periods to get a heavier arrow and now a days the most common is pine. Basically all shorts of wood can be used to create your shaft and it will depend a lot on what weight you want to end up with.. I have used myself port Orford cedar and pine and find the only difference is the really nice smell of cedar when you work the wood, cedar is a little lighter so if you were making arrows for distance then I guess cedar would be a better choice. Incidentally shafts can be pre bought from the supplies with no further work required. However.. i like to do things different I have bought shafts pre made there are standard thicknesses they generally come in 1/4 5/16 11/32 …………more

Bow building on the polder

Well the weekend was getting closer to go to the weekend again this year in warns unfortunately there was not enough people so it got cancelled. I heard this from the the guy organising it I was a little bit annoyed as I was really looking forward to it. Anyhow got on the telephone and talking with one of the guys doing the bowbuilding and told him a suggestion from my wife, that we carried the workshops to my father inlaws farm.. Cool me thinks so it was suggested agreed and organised. The weekend got off to a good start myself Ian and Alan turned up friday evening setup tents and had a beer or two.. whilst cleaning done and setting up the workshop area. Saturday final preparations and no cooked breakfast!! Saturday was basically bow building all day with the expert eye of Ian Blackwell everybody managed to build a bow and really just needed to finish off on sunday morning. We also had a chance to shoot the bows saturday on a field opposite the farm. Saturday was a bbq and a demo for my farther inlaws birthday guests, followed by reminiscing over a few ciders around the fire and boring the hell out of hauke with 1970’s children’s theme tunes Sunday got off to another early morning I managed to get a cooked breakfast going and Ian and hauke enjoyed theirs whilst watching the workers finishing off their bows.. Followed by more shooting and tidying up.. All in all a fantastic weekend thanks to all that made it possible waiting for next time.. The End…..

just in case I lose my notes ;)

Encrypted usbstick Prerequisites A Linux 2.6 kernel with device mapper and dm-crypt support is needed. On Fedora Core 4 systems you really don’t have to do anything as the kernel has device mapper and dm-crypt enabled as modules (dm-mod and dm-crypt respectively). The modules are loaded automatically when the system needs them. Before reading any further, you must be sure that you know the exact device node you are going to encrypt. This is no joke, as you can lose your data, by a simple and fool mistake. So, take note! Furthermore, you need to install cryptsetup-luks package and util-linux package. We will need the latter for encrypting a filesystem within a file, but this is probably already installed. Encrypting a volume In this section I will encrypt a ZIP disk. The very same process can be used for any block device that is a volume, meaning that it can be formatted with a mountable filesystem. So, you can encrypt a hard disk partition, a USB stick, a Compact Flash card etc. First of all, be sure that you know your volume’s exact device node in /dev. If you use multiple hotplugable devices, which you connect to your machine in a random order, you should consider writing some UDEV rules, so that you know which node corresponds with a certain actual device. You can read my blog post on that. A simple mistake can lead to loss of data. I have setup UDEV in a such way, that every time I connect my USB ZIP drive and insert a disk, a symlink to the disk’s node is created in a directory /dev/mydev/. So, I can reach the ZIP diskette by directing the commands to the symlink /dev/mydev/zipdisk. If your volume is already mounted, unmount it before proceeding. Mine is, so I run: # umount /dev/mydev/zipdisk Fill the disk with random data Filling the disk with random data before encrypting is a good habit and it strengthens security as well. If you don’t want to do so, you can simply skip this step. This process is CPU intensive and the time it takes depends on the available CPU horsepower, the size of the partition and the speed it can be written. It can be many hours, even days, for very large hard disk partitions. The worst thing is that there is no progress indicator, so you just wait for it to finish. I run this: # dd if=/dev/urandom of=/dev/mydev/zipdisk Substitute /dev/mydev/zipdisk with the path to your device node. In my case, it took my USB 1.1 ZIP drive 10 whole minutes to fill an 100MB ZIP disk. Well, it’s not the fastest thing in the world, but I still like it. Create the LUKS partition Now, I will create a LUKS partition on the ZIP disk. As root I run: # cryptsetup –verbose –cipher “aes-cbc-essiv:sha256″ –key-size 256 –verify-passphrase luksFormat /dev/mydev/zipdisk If you use a kernel older than 2.6.10, do not include the –cipher option. The default AES with 256-bit key is absolutely fine. Cryptsetup will ask for a passphrase twice. What this does is the initialization of the LUKS partition. Set up the device mapping In order to use this partition, a device mapping must be set up between the physical partition on the ZIP diskette and a new virtual block device, which can then be mounted. I call it virtual because it’s just a layer between the physical ZIP disk and the system. Writes to this virtual block device will be encrypted and reads decrypted. To create the device mapping as root: # cryptsetup luksOpen /dev/mydev/zipdisk encr-zipdisk encr-zipdisk is just a name for the new block device that is created in /dev/mapper/. After creating a filesystem on it, this virtual block device can be mounted and used as normal. Create a filesystem on the new block device You can create any file system you like on the new volume. For my ZIP diskette, an MSDOS FAT16 filesystem is more than enough, so I run as root: # mkdosfs -v -F 16 -n “ENCR1″ /dev/mapper/encr-zipdisk What worths mentioning is that you create the filesystem on the virtual volume, /dev/mapper/encr-zipdisk in my case, and not the physical one. Mount the new volume Now I can mount the volume as normal. For example: # mount -t vfat -o rw /dev/mapper/encr-zipdisk /mnt/tmp/ An fstab entry with all the proper mount options could simplify mounting. All data that is written to the disk gets encrypted. Unmounting Before removing the disk from the drive, I have to unmount it: # umount /mnt/tmp/ And then delete the device mapping as root: # cryptsetup luksClose encr-zipdisk This removes the association and I normally can eject the ZIP disk. In short Just a review of the procedure to mount and unmount the disk, considering that a proper fstab entry has been added. To mount: # cryptsetup luksOpen /dev/mydev/zipdisk encr-zipdisk # mount /dev/mapper/encr-zipdisk To unmount: # umount /dev/mapper/encr-zipdisk # cryptsetup luksClose encr-zipdisk Pretty fast and easy. Encrypt a filesystem within a file In order to use LUKS to encrypt a filesystem that is contained in a file, you actually have to follow the same steps as when encrypting a physical partition, plus two. These include: * The creation of a file that will contain the encrypted partition * Set up an association between this file and a free loop device, so that it can be used by cryptsetup as a block device. At the moment, cryptsetup cannot use a file as a block device directly. That’s why this step is needed. So, let’s create the file. The following command creates an 100MB file, named “container1″, which is full of random data: dd if=/dev/urandom of=container1 bs=1024 count=100000 To create a mapping between this file and a free loop device, we’ll use losetup (part of util-linux). Check which loop device is free in your system with the command: losetup -f For me it was /dev/loop0. So, I map the “container1″ file to /dev/loop0. As root: # losetup /dev/loop0 /path/to/container1 From now on, the steps are exactly the same as before. We just use /dev/loop0 instead of the ZIP disk: # cryptsetup –verbose –cipher “aes-cbc-essiv:sha256″ –key-size 256 –verify-passphrase luksFormat /dev/loop0 # cryptsetup luksOpen /dev/loop0 encr-container1 # mkfs.ext3 /dev/mapper/encr-container1 # mount -t ext3 -o rw,defaults /dev/mapper/encr-container1 /mnt/tmp/ We can now copy some files to our encrypted partition, like on a regular disk partition. We unmount it and delete the device mappings with the following commands: # umount /mnt/tmp/ # cryptsetup luksClose encr-container1 # losetup -d /dev/loop0 So, to mount a LUKS encrypted filesystem within a file you need to create two device mappings before you mount it for use. Of course some automation can be achieved using scripts, but you will still have to supply the passphrase in order to use the encrypted partitions.