How to prevent SDDM from displaying the previous user on the login screen

It’s not a good idea to show the previous user on the login screen. Without it, an attacker has to guess a userid and a password. If the login screen already contains a userid, they just have to guess the password. Here’s how to hide userids if you use SDDM.

Open /etc/sddm.conf in your favourite editor and add the following line to the [Users] section:

RememberLastUser=false

Delete /var/lib/sddm/state.conf or edit it to remove the userid after User=

Reboot or restart SDDM with systemctl restart sddm. NB: restarting SDDM will put you back at the login screen so save anything you’re editing before issuing this command.

A recipe for making 40 litres of sweet mead

This recipe is based on one supplied by Canberra Brewers’ resident mead expert Bro FatBoy. We’ve scaled it up from 5 litres to 40 litres and made minor adjustments to the acid blend quantities to make measurements easier. The results have been quite delicious.

Ingredients:

40 litres of water
15 kilos of ironbark honey (10 litres)
2 tsp of red grape tannin
2 tsp of citric acid powder
2.5 tsp of malic acid powder
3.5 tsp of tartaric acid powder
4 sachets of liquid White Labs WLP720 Sweet Mead Wine Yeast

We purchased our honey from Weerona Apiaries.  They are located at 91 Woodfield Road, Sutton NSW 2620.  Phone: (02) 6230 3237.

Procedure:

Combine ingredients (except yeast) and bring to a gentle boil. Skim the foamy gunk. Force cool and transfer equal amounts to two fermenters. Pitch 2 sachets of yeast in each fermenter. Ferment at 21 degrees celsius in a temperature controlled environment for at least four months. Racking every month or two will produce a visually superior product. Bottle and store for at least six months before sampling. If you can wait that long! Our last batch had OG 1.107. That’s slightly lower than expected but we used more water than intended.

About the boil:

You don’t really have to boil. You need to pasteurize. That involves raising the temperature for a period of time to kill microbes. 15 seconds at 72C will do it, so will 30 minutes at 63C. By bringing it to a boil you ensure it has been at pasteurization temperatures for long enough because it takes a few minutes to get from 72C to boiling which is much longer than the required 15 seconds. You don’t need to boil for any period of time.

You can skip boiling and pasteurization entirely by adding crushed Campden tablets (potassium or sodium metabisulfite) and pitching the yeast 24 hours later. Use 1 Campden tablet per 3.8 litres (1 US gallon). 10 Campden tablets are equivalent to one level teaspoon (5 ml) of sodium metabisulfite.

Update 1: This recipe produced the highest scoring mead in the 2018 ACT Amateur Brewing Championship.

Update 2: This recipe was also judged second best mead in the 2018 Australian Amateur Brewing Championship.

MythTV channel icons for Canberra TV stations (July 2019 update)

Extract this tar archive to /home/mythtv/.mythtv/channels, then manually add with the mythtv-setup channel editor.

The icons below are the correct size for MythTV. If you don’t want everything, you can right click on an image and save it somewhere. The $religious channel has been intentionally excluded. This is what you get:

   

Other sources of Australian channel icons:
http://www.lighterra.com/mythtvchannelicons/
http://www.wolffhaven45.com/blog/xbmc/australia-tv-logos/
http://www.xmlepg.net/?page=list&b=201

NOTE: The above logos are copyright their respective owners and are used here under fair use.

x3270 configuration tips

x3270 is an excellent mainframe terminal emulator for Linux but I don’t like its default setup. These are the changes I like to make.

Modify the keyboard map

Make the right ctrl the enter key and the enter key a newline key just like on a real terminal. This also makes the page up and page down buttons work like PF7 and PF8 and makes the end key work the way I like to have it in PCOMM.

Create the file ~/.Xdefaults if it doesn’t already exist.

Paste the following in to ~/.Xdefaults exactly as it appears here, including the \n\ at the end of most lines. Ensure there are no blanks after the last slash on each line.

x3270.keymap.default: \
<Key>Pause: Clear()\n\
<Key>Escape: Reset()\n\
<Key>Insert: ToggleInsert()\n\
<Key>Return: Newline()\n\
<Key>Control_R: Enter()\n\
Ctrl<Key>End: EraseEOF()\n\
<Key>End: FieldEnd()\n\
<Key>Prior: PF(7)\n\
<Key>Next: PF(8)\n\

Then enter this command:

xrdb -merge .Xdefaults

In x3270, click Options, Change Keymap and enter “default”.

Fix insert behaviour

In x3270, click Options, Toggles and then Blank Fill

Fix pasting

In x3270, click Options, Toggles and then Paste with Left Margin

Save the changes

In x3270, click File and then Save Changed Options. Save to the suggested file.

How to Burtonise Canberra tap water

Burtonising is the process of adding salts to water to give it the same chemical composition as Burton-On-Trent water in the UK. This is desirable because Burton-On-Trent water is renowned for producing exceptional ales. Here’s what needs to be added to 25 litres of Canberra tap water to Burtonise it.

Gypsum ( CaSO4 ) 23.1g
Epsom Salt ( MgSO4 ) 14.5g
Baking Soda ( NaHCO3 ) 2.64g
Calcium Chloride ( CaCl ) 1.98g

Those figures were provided by Martin on the Canberra Brewers forums.

Brew day checklist

This is the list I use when I brew. I created it because I would sometimes forget to do something. Feel free to disagree with the way I do things and feel free to find someone who cares 🙂

The Mash

1. Add S bend pipe to inside of boiler
2. Start heating mash water
3. Add mineral salts to mash water
4. Attach false bottom to mash tun
5. Pour cracked grain in to mash tun (outside the house)
6. Switch off immersion elements when mash water is 80 degrees
7. Boil kettle in case the mash temperature needs to be adjusted upwards
8. Pour mash water on to grain, through colander and stirring to break up clumps
9. Adjust the mash temperature to suit the recipe

During The Mash

1. Boil water to sterilise the counter flow chiller
2. Run boiling water through the counter flow chiller
3. Sterilise fermenters
4. Heat sparge water 30 mins before the end of the mash. Include any mineral salts.

End Of The Mash (Batch sparge, do 3 times)

1. Recirculate wort until clear
2. Drain wort until flow stops
3. Add more sparge water and stir
4. Wait 5 minutes and repeat

Start Of Boil

1. Switch on both immersion elements
2. Empty spent grain on to garden
3. Rinse mash tun
4. Prepare bittering hops
5. Wait for boil
6. Turn off one immersion element
7. Add bittering hops
8. Set timer for next hop addition

During The Boil

1. Turn on the second immersion element after 15 minutes
2. Measure remaining hop additions
3. Measure whirfloc and place with hops
4. Fill sink with iodophor solution
5. In the sink, sterilise the wort stirrer, airlocks and the hose that goes from the counterflow chiller to the fermenters
6. Take dried yeast out of the fridge
7. Add flavour hops when the timer beeps
8. Add whirfloc 15 mins before the end of the boil

End Of Boil

1. Turn off and remove the immersion elements
2. Add aroma hops
3. Whirlpool
4. Add cold tap water to replace water lost during the boil. Add it so that the flow contributes to the whirlpool.
5. Wait 5 minutes
6. Chill wort and fill fermenters. Splash the surface of the wort as the fermenters fill
7. Measure gravity
8. Add dried yeast
9. Attach fermenter lids and attach airlocks

Digital TV frequencies for Tuggeranong

These are the frequencies for digital TV stations broadcast by the Tuggeranong Hill repeater. Do not use these frequencies if your antenna points at Black Mountain or Mount Taylor.

Station Frequency (MHz) Frequency (Hz)
SBS 648.5 648 500 000
ABC 620.5 620 500 000
SC10 641.5 641 500 000
WIN 634.5 634 500 000
PRIME 627.5 627 500 000

MythTV expects frequencies to be entered as Hz. Most equipment uses MHz.