April 2014 – Page 2 – Kev's Development Toolbox

April 9, 2014

Windows 8.1 update 4/8/14

I picked up the 4/8/14 Windows 8.1 update today and was pleased that the Metro apps can now appear in the ‘classic’ desktop taskbar. It still seems odd to me that Windows 8 has two distinctly different personalities – the touchscreen friendly Metro apps from the new Start screen, and the classic desktop with regular looking Windows apps. It just seems confused to me – which is it? A post-PC touchscreen OS or a classic Windows desktop? Well, now at least the two are somewhat more combined.

Rather more odd however is that this cumulative update is required if you want to continue to receive Windows Updates. Pretty sure some internal IT departments are going to be pretty annoyed with this approach – “You want updates in the future? Install every update up to this date then we’ll give you new updates”. Uhuh.

April 8, 2014

Enabling i2c on Raspbian

Add the following to /etc/modules:

i2c-bcm2708
i2c-dev

Install i2c-tools:

sudo apt-get install i2ctools

Edit /etc/modprobe.d/raspi-blacklist.conf and remove/comment out these two lines:

blacklist spi-bcm2708
blacklist i2c-bcm2708

Detect your ic2 interface with:

sudo i2cdetect -y 1 #1 = Pi model B

If you get this error:

Error: Could not open file '/dev/i2c-1' or `/dev/i2c/1': No such file or directory

Then run this first and you should be good to go:

sudo modprobe i2c-dev

More info here.

April 3, 2014

Disabling strict key checking on ssh

Key checking on ssh validates that the remote system you’re attempting to connect to is the same server that you connected to the last time, to help prevent the possibility that someone has hijacked the DNS name, IP, or the hardware itself.

However, some times you may want to avoid this checking. For example, I have a Raspberry Pi that I boot from multiple SD cards, but each is setup with the same IP. If strict key checking is enabled then your ssh client will prevent you from connecting when it detects a signature change. You’ll see this error:

RSA host key for 192.168.x.x has changed and you have requested strict checking.

To avoid this, edit or add ~/.ssh/config, and add:

Host 192.168.x.x
    StrictHostKeyChecking no

where the IP can be the IP of the machine you’re connecting to, or you can use a * wildcard too (maybe not as secure).

If you’ve already connected and have a key in your known_hosts, then I think you need to delete this entry first, and then try with this config.