I have always wanted to be able to put my Mac Pro to sleep using the power button on the Dell display I have connected to it. If you put the Mac to sleep and then turn off the display it will wake the mac up again due to the USB disconnect of the USB hub in the display.

I came across sleepwatcher which allows you to do stuff like this

Create a config file containing something like 

timeout=100
idle=if [ `system_profiler SPUSBDataType | grep "Apple Keyboard" > /dev/null; \
    echo $?` -eq 1 ]; then /usr/local/sbin/sleepwatcher -n;fi

(I have my Apple Keyboard connected to the USB hub in the display.) Then edit the sleepwatcher Launch script to use that config file - make the launch command look like this

/usr/local/sbin/sleepwatcher -d -V -s /etc/rc.sleep -w /etc/rc.wakeup -f /config/file

Restart sleepwatcher and press the power button on your display and wait 10 seconds…

Now must just remember that this will occur whenever I disconnect the keyboard.

Bert Hubert published a description of the math behind this attack on namedroppers and I have been playing with the spoofer to see how close I can get the experiment and theory. 

I ran my spoofer on a network consisting of three machines linked by a cheap gigabit switch. The attacker was on a Mac Pro, the target nameserver was on a Mac Book Pro and the authoritative server, that the attacker was pretending to be, was on a old FreeBSD box (100Mb). I used DUMMYNET to simulate a longer link to the authoritative server (delay = 30ms).

I ran the spoofer 1000 times and plotted a histogram of the frequency of success against time.

The pink bar shows the median of all the times recorded. If I recall my A level maths correctly, this should coincide with the 50% chance of success predicted by the math.

The math presented by Bert Hubert considers the expansion of the binomial 

Ps = probability of success on a single attempt

Pf = probability of failure on a single attempt

( Ps + Pf )^n = 1

Expanding this and remembering that the sum of all the terms containing success = (1- the term for always failing) leads to the probability of combined success

Pcs(n) = 1 - (1 - Ps)^(n)

We know that n = T/W so we get 

Pcs(t) = 1 - (1 - Ps)^(t/W)

Bert Hubert tells us that Ps = (D*R*W)/(N*P*I) where

     I: Number distinct IDs available (maximum 65536)

     P: Number of ports used (maximum around 64000 as ports under 1024
     are not always available, but often 1)

     N: Number of authoritative nameservers for a domain (averages
     around 2.5)

     R: Number of packets sent per second by the attacker

     W: Window of opportunity, in seconds.  Bounded by the response
     time of the authoritative servers (often 0.1s)

     D: Average number of identical outstanding queries of a resolver
     (typically 1, see Section 5)

I used the following values
I=65535
R=36000 - From looking at the traffic I was sending
W=0.030 - From the settings I gave DUMMYNET
N=1.0 (I fixed this)
P=1 (I fixed this)
D=1
Plotting this on the same graph as the histogram gives:

The blue circles are the predicted probability of combined success (Their y axis runs from 0 to 1 and is not shown). As you can see the predicted 50% chance (black cross lines) occurs slightly before the median but it is fairly close.

In order to improve things I added an extra term to the equation to account for the time that the window is closed (This is due to the spoofer taking a bit of time to notice that it has been unsuccessful and to try again). So:

n = T/(W+Wc)

Ps = (D*R*W))/(N*P*I)

where Wc is measured to be about 0.003 seconds. The graph now looks like

That seems like good agreement to me. The median in this case is 1386ms.

BTW: The graphs were plotted using R.  This is the code I used

#Plot a histogram of frequency of success against time
mydata <- read.table("/tmp/speed-test-30ms",header=TRUE)
#Plot both on a single graph
h <- hist(mydata$time,breaks=100,plot=FALSE)
plot(h,freq=FALSE, xlim=range(h$mids),ylim=range(h$density),
    sub="Histogram showing time to success of real spoofer (pink line shows median)",
    main="DNS Spoofer Performance",
    ylab="Density", xlab="Time/ms")
abline(v=median(mydata$time),col=70)
#Plot Bert Hubert's math
D=1.0
R=36000.0
W=0.030
Wc=0.003
N=1.0
P=1
I=65535
Ps <- ((D*R*W)/(N*P*I))
Pcs <- function(t){1 - (1 - Ps)**((t/1000)/(W+Wc))}
par(new=TRUE)
nx <- sample(h$mids)
y=Pcs(nx)
#Scale plot to same as histogram
my=max(y)
ny=y*max(h$density)/my
plot(nx,ny, xlim=range(h$mids),ylim=range(h$density),col="blue", ann=FALSE)
#Calculate time for 0.5 chance
time5 = 1000*(W+Wc)*(log10(0.5)/log10(1 - Ps))
abline(v=time5)
abline(h=0.5*max(h$density)/my)

Does anyone else see this or is it just me?

But where does it store the settings? Traditionally you would have added a clause like

AllowUsers jad

/private/var/db/dslocal/nodes/Default/groups/com.apple.access_ssh.plist

When you are controlling your computer you have to be careful to use the correct language and it does take a bit of getting used to but it’s quite easy. There is an on-screen list of commands to refer to and most of them are fairly intuitive.

As far as I can tell MacSpeech Dictate seems  to work in all applications. I have used it this morning in TextMate to write an XML document. Speaking “open angle bracket” is almost as easy as typing angle bracket. And long sections of text are obviously much easier to speak.

MacSpeech Dictate is able to detect commands during spoken text. Adding punctuation is easy, to add a full stop just say “full stop”. Correcting mistakes can be a little painful but can be done. Deleting a single word is done by saying “forget word” and deleting the last chunk of text that you dictated can be done by saying “forget that”.

It is really good in iChat. Being able to speak is exactly what you want when writing a chat message.

However, don’t forget to read what you wrote because it can make mistakes!

That file contains this:

!SESSION 2008-07-08 08:34:44.307 -----------------------------------------------
eclipse.buildId=I20080617-2000
java.version=1.5.0_13
java.vendor=Apple Inc.
BootLoader constants: OS=macosx, ARCH=x86, WS=carbon, NL=en_US
Framework arguments: -keyring /Users/jad/.eclipse_keyring -showlocation
Command-line arguments: -os macosx -ws carbon -arch x86 -keyring /Users/jad/.eclipse_keyring -consoleLog -showlocation

!ENTRY org.eclipse.osgi 4 0 2008-07-08 08:34:45.312
!MESSAGE Application error
!STACK 1
org.eclipse.swt.SWTError: No more handles
at org.eclipse.swt.SWT.error(SWT.java:3803)
at org.eclipse.swt.SWT.error(SWT.java:3695)
at org.eclipse.swt.SWT.error(SWT.java:3666)
at org.eclipse.swt.widgets.Display.createOverlayWindow(Display.java:741)
at org.eclipse.swt.widgets.Display.internal_new_GC(Display.java:2300)
at org.eclipse.swt.graphics.GC.(GC.java:149)
at org.eclipse.swt.graphics.GC.(GC.java:115)
...

Why do I need all the junk? Why didn’t the message on the screen just say something like. “Sorry, the application failed to start. The reason was - No more handles.”. Even better, it could explain what a handle is and how to fix it or provide a link to a knowledge base.
 

export COPYFILE_DISABLE=true

Thanks to this thread for the answer.

Add the following line to /etc/modprobe.d/options
options forcedeth msi=0 msix=0
Then rebuild initramfs like this
sudo update-initramfs -u

BTW - this was the only issue I came across doing the upgrade over ssh. Everything else worked perfectly.

To start with I used the Rails install that comes with OS X. I did something like 

rails mythrails
cd mythrails
#edit database.yml
ruby script/generate scaffold Program program


Since this is a so called legacy application you need to edit config environment.rb to tell rails not to pluralize table names

ActiveRecord::Base.pluralize_table_names = false


and edit the model to tell it what the table is actually called

class Program < ActiveRecord::Base
  set_table_name "capturecard"
end


then starting the web server gives you a web interface to the program table. It’s really simple. But …

If you try to edit the data or create a new entry it will complain because (I think) there is no id field in the program table. This lead me to discover that you can add something like

class Program < ActiveRecord::Base
  set_table_name "capturecard"
  set_primary_key "the_id_field"
end


This raises the next problem. Rails can not cope with composite primary keys. You need to install composite_primary_keys. However, this leads to the next issue - composite_primary_keys needs Rails 2. This then has the side effect that generating the scaffold no longer works. In Rails 2 you need to specify the fields and types for all the fields in the table. In the case of a legacy system the table already exists so why can’t the scaffold generator just read the fields from the database?

At this point I gave up. I am sure this is not too hard to work around but I only wanted to play and this all seemed like it was getting harder than I ever intended.