SCCM – Duplicate Hardware Identifiers

8 Jan

Once upon a time, all computers came with an Ethernet port and the MAC address of that was effectively an identifier for the computer. If you configured SCCM to only deliver a boot image to unknown hardware then everything worked – a new machine would install but trying to PXE once it was installed got you nowhere.

Times change and it’s now extremely common for laptops to come without wired Ethernet (and even without Wi-Fi if you use HP but that’s another story …) To install them we can use USB Ethernet adapters or docking stations but we need a way to tell SCCM to allow reuse of a MAC address. In versions of SCCM prior to 1610 this was done by adding MAC addresses to a REG_MULTI_SZ value under the key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\SMS\Components \SMS_DISCOVERY_DATA_MANAGER . This worked but wasn’t easy to do – you had to make sure you got the format exactly right and you had to be able to edit the registry of a site server.

Since SCCM 1610, this has changed. You can now add MAC addresses through the console (Administration > Overview > Site Configuration > Sites > <Site> > Hierarchy Settings > Client Approval and Conflicting Records.

We want to make it easy for the deskside support engineers to see the list of MAC addresses. In the older version I just ran a script at regular intervals to dump the list from the registry to a web page that they could read. I wanted to do the same with the new system so had to find out where the MAC addresses are stored – the console doesn’t just give an easier interface to the registry key.

I guessed it would be in the SQL database but finding the right table proved difficult. A bit of Googling found which told me how to get a list of all the fields in every table in a database. A small edit gave me this query:

SELECT AS Table_Name , AS Column_Name , AS Data_Type ,
 P.max_length AS Size ,
 CAST(P.precision AS VARCHAR) + '/' + CAST(P.scale AS VARCHAR) AS Precision_Scale
FROM sys.objects AS T
 JOIN sys.columns AS C ON T.object_id = C.object_id
 JOIN sys.types AS P ON C.system_type_id = P.system_type_id
WHERE T.type_desc = 'USER_TABLE' and like 'mac%' and<>'machineid'


with just 49 rows in the result set it was pretty easy to find the table called “CommonMACAddresses” and a quick check of its contents showed me I’d found the right table.



Mini Vegetarian Moussaka

19 Oct

I’ve been in a really indecisive mood trying to choose what to cook for a dinner party tonight. Normally, a quick search of the internet brings up some good ideas but nothing inspired me this week.

In the end I decided to make a vegetarian starter – none of my guests is vegetarian but I”m doing roast lamb for the main course so I thought a contrast would be nice!

I tried finding a recipe but couldn’t find one I really liked so I invented my own!

I’m afraid the quantities are a bit vague but I think that’s part of the fun of cooking like this. My aim is to make 7 ramekin size portions so I started by measuring out 3 ramekins of red lentils into a pan, covering with water and cooking for about 10 minutes (the lentils will absorb the water – add more if it looks too dry and don’t let it stick to the pan).

While that’s cooking, chop a couple of onions and sweat gently in oil – I’m using sun dried tomatoes as well so use some of the oil from the jar of tomatoes.

Finely chop a few sun dried tomatoes (you need about 2 tomato “chunks” per person to get a good flavour) and then mix the cooked lentils with the onions and tomatoes. Add salt, pepper and spice to taste (I added some chilli powder and ginger powder and some ground black pepper). Dollop into the ramekin so it’s not quite full.

Slice some large tomatoes and place a slice of tomato on top of the mix – that can now go in the fridge until later.

When you’re ready to serve, slice an aubergine (you want discs, ideally the size of the ramekin). Fry the discs with a very little oil until they’re soft (only a couple of minutes; turn part way through).

While they’re cooking, slice some mozzarella – you want circles, again about the size of the ramekin. Cover the lentil and tomato with aubergine, put mozzarella on the top and put in the oven at about 100C-150C just to keep warm and to let the cheese melt.

Iceland – moving inland

10 Jun

The people give a sense of scale to the caldera

A caldera looks like it might be the crater of a volcano but it’s actually caused by land collapsing after a volcanic eruption. Wikipedia has a good description but Kerio is pretty impressive!

I took a few photos here, including ones of the information boards. The boards are really impressive and present at most of the sites of interest – they were all in Icelandic and English with other languages added occasionally.

We didn’t spend long here because we had a lot more to see and the next stop was at the visitor centre for Þingvellir (the “Þ” is pronounced “th”) This is important because it’s the site of the original Icelandic parliament but it’s geologically important because it effectively straddles the rift between the North American and Eurasian tectonic plates. You can pretend to stand with feet on either side of the gap which makes it well worth a visit 🙂

The visitor centre is interesting and has good toilets (actually, all the public toilets in Iceland are good – there just aren’t very many of them!) but it also gives an excellent overview of the area. You used to be able to walk from the centre down into the valley but recently a crack has opened up which means that the path has been closed. There’s some rope lava here which you can see  in my photos (rope lava is also known by the Hawaiian name of pahoehoe) and a good model showing the area.

Waterfall at Þingvellir We got back on the coach to go a bit a further along the road and then had a pretty easy walk down into the valley. The weather had really improved and it was actually a really gorgeous day – not at all what you expect in Iceland (2 weeks before we went the temperature was about -10C!)

One of the Icelandic words you see often is “foss” – it means waterfall and you’ll see it often because there are lots of them – the one at Þingvellir isn’t the biggest but it’s quite impressive.

There are more information boards in the area where the parliament met including information about the punishments meted out for various crimes. Given the amount of water I suppose it’s not surprising that drowning was used as a form of execution although apparently only women were drowned. Men were beheaded, hung or burned at the stake.

The sunshine meant that our picnic lunch (provided by the Hotel Dyrholaey and pretty good) was in the sunshine next to the river. The river is absolutely crystal clear (which tells you that it’s not glacier melt – water from a glacier is always cloudy because of the rock flour it carries) but it’s spoiled by people throwing coins into it in spite of the pictogram signs everywhere saying “don’t throw coins”

After lunch we made our way to Geysir. The Great Geysir rarely erupts now but Strokkur goes off about every 10 minutes and is really good to watch (not quite sure why I bothered to upload my video clip – there are far more, far better ones on YouTube already!)


Gulfoss with a touch of rainbow!

The next stop was Gulfoss – one of the biggest waterfalls and very spectacular.

The information board says that the average water flow is 109 m3/s but peaks at 2000; 1m3 of water weighs 1 tonne so that means that there can be 2 000 tonnes of water going over the fall very second! You start to realise just how destructive water can be with figures like that.

It was hard to get good photographs but I’ve put a few here and also uploaded a video (but, again, there are many more available!) I think the video gives an idea of how sunny it was but I should have included people to give an idea of the sheer size of the waterfall.

TV Tuners in Linux

10 Jun

I have an elderly PC running MythTV which has worked well for sometime but the USB TV Tuner I was using failed. Not a major problem; they’re cheap to replace. Unfortunately, the software support is not too good – few manufacturers provide Linux drivers and firmware. I bought my tuner from Maplin (and I’ve just found that it’s now £10 cheaper than when I bought it!) – it’s a KWorld UB499-2T.

A new install of Ubuntu 12.04 almost works (but, as my old German teacher used to say, “If you’re nearly right, you’re wrong” so “almost works” really means “doesn’t work”) so I decided to find out how to make it work. This was not as easy as I hoped so I’ve made some notes which will help me next time I reinstall and might perhaps help someone else!

There are lots of articles on the web which refer to the script “get_dvb_firmware” and just seem to assume it will be present. It’s not present on a default install of Ubuntu but it gets installed if you add the linux-doc package (at least, /usr/share/doc/linux-doc/dvb/get_dvb_firmware.gz gets installed; copy that somewhere safe, unzip it and make it executable) Run the code to get the firmware and then unload/reload the driver

cd ~
cp /usr/share/doc/linux-doc/dvb/get_dvb_firmware.gz .
gunzip get_dvb_firmware.gz
chmod +x get_dvb_firmware
#get the firmware
./get_dvb_firmware it9135
#copy it to the right location
sudo cp dvb-usb-it9137-01.fw /lib/firmware
#Now unload and reload the driver (you could just reboot but Linux never needs rebooting ...)
sudo rmmod dvb_usb_it913x
sudo insmod /lib/modules/3.2.0-24-generic-pae/kernel/drivers/media/dvb/dvb-usb/dvb-usb-it913x.ko

If you now run dmesg you should see that the tuner is found, firmware is loaded and the tuner is ready.

The Kaffeine media player is really good for checking that the tuner is working – stop the Mythbackend service because otherwise it grabs the device.

Iceland – Day 2

30 May

After breakfast we set off in our bus (Lady Scania!) for Solheimajokull – a very large glacier.

The first think you notice is that it’s grey because it’s covered in ash but as you get closer you can see the clean ice and it’s a pretty amazing sight.  The picture hopefully gives an idea of the scale – it’s massive – and some of the pictures here give an idea of the amount of ice in the glacier. It was strangely beautiful but the most interesting thing is the speed at which it’s melting – our guide was last here less than 2 months ago and it’s retreated since then,

We then drove along the main road to Vik -a small town on the coast. You can see a few photos of the town here. The lupins in the picture are not native to Iceland; they were imported from Canada and were planted in a bid to stabilise the sand/ash. Unfortunately, they’ve been much more successful than was expected and are taking over! Apparently, they are being pulled up in parts of the island because they’ve simply become too dominant.

After a lovely coffee break we went down on to the beach. The pictures may not be too clear but the thing which is spectacular about all the beaches here is that the sand is black – all the rock is volcanic so when it gets broken down to sand (it’s actually more like fine grit) it’s also black. It looks pretty spectacular when it’s wet.

Walking up the hillVik is a small town but it does have  a store selling Icelandic woolen products (and many more souvenirs). Their website only lists a fraction of what they sell; I bought a superb hat for about a tenner ( I thought I’d need a hat and I’d managed to leave my own hat at home. As it happened, this day was the only cool day in the whole week so I didn’t really need a hat. It’s such a good hat that I’m sure it will be useful later!)

We had lunch at Hjörleifshöfði (I think; my Icelandic spelling is not too good! I decided not to go up the hill and just wandered around near the beach. Even down at that level the scenery is amazing.

Basalt Columns Reynisfjara was our next stop – this has the most spectacular basalt columns which you can hopefully make out in the photos. Unfortunately, the weather was getting greyer so the light wasn’t too good but it’s still fantastic to see the scenery.


The final stop was Dyrholaey – “Door hole” in Icelandic. It’s a natural rock arch but sadly I failed to get a decent photo of it!


Iceland – day 1

29 May

We flew with Icelandair from Heathrow to Keflavik; the flight left an hour late but we made good time and arrived just 30 minutes late. We were met at the airport by our Trex coach and driver. I can’t spell his name but it’s pronounced “Yoey” (rhymes with Joey) who has turned out to be an amazing asset – a good driver, with a huge knowledge of the country, a good command of English and a willingness to get stuck in with every aspect of our holiday!

The Blue Lagoon

Steamy waters

From the airport we made our way to The Blue Lagoon This is a huge outdoor pool with geothermally heated water and it’s blue because the silica (basically very fine sand in the water) refracts the light and makes it blue. It’s a fabulous place; the water is mineral rich which means that even if you can’t swim, you can just float around in the pool and even at it’s deepest it only comes up to chest height so you can easily walk around. There are also saunas and steam rooms if you want a little more warmth.

Iceland can be a cold place (the clue is in the name!) so a good tip is to not go out through the main door from the changing room. Instead, get in the small pool by the door and then go through the door at the far side of the pool; this way you stay in the warm water and the cold air is not quite such a shock!

My photos of the Blue Lagoon are here

From there we made our way to Hotel Dyrholaey just outside Vik. We arrived quite late in the evening but sunset in Iceland at the end of May is after 2300 so at least the drive was in daylight. The hotel proved to be lovely – the staff were charming and very helpful and the accomodation perfect for our needs.

Audley End House

23 Apr

The weather’s been grey recently but yesterday morning the sun was shining so I decided to go to Audley End House – an English Heritage property near Saffron Walden. I was nearly thwarted by tube disruption and then staff at Liverpool Street telling me you can’t get there on the Stansted Express (you can; you just change at Harlow Town and it’s a lot quicker than the stopping train they told me to get!)

A rabbit in the sunIt’s a walk of just over a mile from the station to Audley End House but most of it is along country lanes (with rabbits off to the side) so it’s a pleasant enough walk and I arrived to see the house looking splendid in the sun.

I spent the firsst hour or so just exploring the grounds; there’s a mix of formal garden, open space with lakes and a huge kitchen garden which has been restored and is being run as it would have been in Victorian times. There used to be a huge variety of apples available in the UK but in the recent past most of these have pretty much vanished – if you go to many shops you’ll be lucky if you see even half a dozen different varieties but at Audley End they have dozens of them. It’s much too early to see the apples growing but the trees are all in blossom and look very pretty. My completely unscientific sampling suggests that pear blossom is always white but apple blossoms are mostly pink and white. I can’t find any evidence for this but the colours are very pretty.

Near the vegetable garden are the stables – they’re now mostly used for exhibits but there were 2 horses there yesterday eating their hay energetically!

Before I got to the house I noticed a large number of plants for sale. The plants were similar to those you could buy in any garden centre but the really interesting thing was the pots – they were hairy! The Hairy Pot Plant Company uses coir to make pots which can simply be planted directly into the ground. The pot is fibrous so roots grow through the gaps and eventually the pot just bio-degrades. It’s a brilliant idea – you can buy directly from the web site and there’s also a list of stockists.

The house is absolutely spectacular but what you actually see is a tiny fraction of what was once there – lack of money to maintain the house meant that about three quarters of the building was demolished several centuries ago but it’s still an enormous building. The English Heritage website has lots of information about it (including several virtual room tours to whet your appetite). The guided tour takes a good hour and if all the guides are as good as the one we had then you will learn an amazing amount about the place.

This is the second time I’ve been to Audley End (I’m a member of English Heritage). Here are the photos from my 2008 visit and the photos from 2012.