Fully disable User Access Control (UAC) via Group Policy (GPO)

I'm sure Windows' User Access Control is a wonderful idea and dramatically improved security levels of this once-beleaugured operating system. Unfortunately, most COM/DCOM-based software was written before 2007 and simply doesn't like it (cough*Oracle EPM Financial Management*cough); 6 years later, we're still forced to disable it in many cases.

This is usually achieved through Active Directory policies. Most documents and guides will tell you that you just need to turn off three policies in Windows 2008, under Computer Configuration -> Policies -> Windows Settings -> Security Settings -> Local Policies -> Security Options:

• User Account Control: Behavior of the elevation prompt for administrators in Admin Approval Mode (set to Elevate without prompting)
• User Account Control: Detect application installations and prompt for elevation (set to Disabled)
• User Account Control: Run all administrators in Admin Approval Mode (set to Disabled)

Unfortunately, this will bring that lovely UAC slider all the way down, but will still results in a weird behaviour where local administrators have most rights but not all of them. The typical test I perform is to open a regular Command Prompt and try to navigate to C:\Windows\SysWOW64\Config - if I get an Access Denied message, then UAC is still lurking in the shadows.

The extra kick we need is, from my tests, this:

• User Account Control: Only elevate UIAccess applications that are installed in secure locations (set to Disabled)

As explained on the technet site, this policy refuses to elevate applications that don't live in "secure locations" (i.e. %windir% or Program Files). It makes sense that such a policy would affect third-party software dropping executables in their own home folders (cough*lots of Java stuff*cough), but why cmd.exe? No idea, but there you are. For all intents and purposes, UAC is completely turned off only when all these four policies are disabled; miss one of them, and things will get weird. 

I wish Microsoft had just given us a big button that said Behave like Windows 2003, but I guess it wouldn't have sold new manuals and certification lessons.

Apple Firewire-related update resulting in USB disk not mounting - fix

Last night Apple pushed a small OSX update, purportedly related to Firmware. It required a reboot and completed successfully. Unfortunately, it also stopped one of my external USB disks from mounting. Others were mounting fine, but this disk (which was mounted the night before, during the upgrade, and removed after shutdown) couldn't be seen.

To say I was scared to death is an understatement: there's always a chance that problems like these are due to hardware issues. Unfortunately, Solid State Device (SSD) disks have a limited life and will eventually fail. This was a 500 GB disk with a lot of very useful stuff on, programs I need every week or so, now-untrovable applications, etc. Before I'd let go of this baby, I wanted to go to the bottom of it.

Almighty Google pointed me to an old post mentioning USBProber but it didn't mention what USBProber is (a debug tool by Apple) nor where I could find it (it's not installed on OSX by default, at least not on 10.8 Mountain Lion). Luckily, another blogger mentioned it, and I could finally get it from the Apple site: you will find USBProber at the Apple Developer Site under the name "IOUSBFamily Log". I got the 10.8 version and installed the package ending in "-Log", as instructed.

USBProber.app can be found under /DevTools/Hardware. Once launched, it gives you a number of options to track USB activity. I'm not a hardware hacker, I only have a cursory knowledge of Plug and Play mechanics from my old Linux days, so I poked and prodded here and there without much luck. Eventually, what seems to have done the trick was to select "Bus Probe", ticking "Probe suspended devices", and then hitting "Refresh" several times, until the drive appeared in the list. Switching to Finder, I could see that the drive was in fact mounted, and all contents were displayed. Phew.

I hope this is not something I'll have to do over and over. Hopefully I'm not the only one to see this issue, and Apple will eventually push a correction. Meanwhile, USBProbe looks like a nice find to troubleshoot problems like this, and hopefully this post will be useful to people in the same situation.

Referendum sul Finanziamento delle Materne a Bologna - strumento di analisi

(Apologies, this post is for Italian readers only.)

Il 26 Maggio a Bologna si terrà un referendum consultivo sul finanziamento comunale delle scuole materne pubbliche e private.

Il quesito chiede agli elettori se i finanziamenti dovrebbero dare priorità alla scuola pubblica (opzione A) piuttosto che continuare a sostenere parzialmente le scuole paritarie private (opzione B). In pratica, si chiede un giudizio sul finanziamento che il Comune eroga dal 1995 alle materne private grazie a una delibera del sindaco di allora, Walter Vitali, approvato nel 1994. Il contributo iniziale (circa 300mila Euro) è cresciuto nel tempo fino agli attuali 1,2 milioni di Euro, in un contesto in cui le scuole comunali si trovano invece in notevoli difficoltà economiche per colpa dei tagli alle amministrazioni locali da parte dei vari governi nazionali. Centinaia di bambini vengono così privati del loro diritto all'istruzione; solo una parte di questi può permettersi di accedere ad una scuola privata, vuoi per ragioni economiche (le paritarie richiedono rette tra i 200 e i 500 euro mensili) o per ragioni culturali (oltre il 90% delle scuole paritarie sono gestite da vari organizzazioni che fanno capo alla Chiesa Cattolica, elemento che si riflette esplicitamente nei loro programmi e regolamenti e, di fatto, nella composizione delle famiglie che ne usufruiscono). Nel 2012/13, 143 bambini sono dovuti rimanere fuori; simili proiezioni circolano per il 2013/14.

È chiaro che la scelta di chi finanziare con i soldi dei contribuenti è sempre squisitamente politica. L'amministrazione attuale, capitanata dal sindaco Virginio Merola, si è schierata pesantemente a favore del mantenimento dei contributi ai privati ed ha fortemente voluto uno scontro frontale con i referendari. In particolare, da subito il "fronte del B" (che annovera praticamente tutti i partiti maggiori, inclusi quelli di opposizione) ha sostenuto come questa scelta fosse fortemente pragmatica perché, si afferma, non ci sarebbero comunque i soldi per garantire a tutti un posto in scuole pubbliche.

Per discutere di questa affermazione, ho creato un banale strumento per calcolare il budget delle scuole paritarie e pubbliche a Bologna. Lo strumento mostra come, reindirizzando i contributi pubblici verso scuole comunali, è altamente probabile che si troverebbe lo spazio per accomodare tutti. Cercando di essere obiettivo, lo strumento mostra anche il possibile impatto sulle rette delle scuole private -- che in realtà era la mia motivazione originale quando ho iniziato a lavorarci. I dati utilizzati sono quelli forniti dallo stesso Comune in una pagina recentemente pubblicata e criticata per i toni non particolarmente super partes.

La critica più facile verso questo strumento è che assume che la domanda per posti privati non sia influenzata dalle possibili variazioni della retta. Purtroppo questo non è calcolabile senza il dato delle iscrizioni pre-1995, dato che il Comune si guarda bene dal divulgare nonostante le richieste [EDIT: il Comune ha risposto, dicendo che i posti pre-95 erano "circa 1600"]. Le cifre ufficiose parlano di 1660 iscritti nel '94, contro gli attuali 1736 (o 1961, a seconda se si includono le scuole private tutt'ora non aderenti alla convenzione); se fosse vero, mostrerebbe che quindi l'influenza dei cntributi è complessivamente marginale rispetto alla domanda, e quindi il mio modello rimarrebbe è sostanzialmente valido. Sono comunque aperto a discutere qualsiasi lacuna: il codice utilizzato è disponibile pubblicamente su Github.

Per concludere, è chiaro che questo discorso è riduttivo. Il referendum non è solo questione di soldi: in ballo ci sono principi e indirizzi fondamentali a livello etico e politico su chi e come debba gestire l'educazione. Il modello sussidiario, che tanto andava in voga 20 anni fa sull'onda privatizzatoria del post-89, ormai mostra le crepe in Italia come in gran parte d'Europa. Si ricomincia a discutere del ruolo fondamentale dello Stato di tutti, dei beni comuni, del ruolo sociale delle istituzioni collettive; in quest'ottica, è doveroso ridiscutere scelte fatte quasi in sordina (e spesso in una logica di voto di scambio) su cui i bolognesi non hanno mai potuto esprimersi. Questo strumento è solo una risposta all'approccio pragmaticista su cui l'amministrazione comunale ha impostato la sua campagna fino a pochi giorni fa.

Da buon iscritto AIRE, anch'io posso votare e cercherò di farlo, nonostante le difficoltà logistiche del caso.

Clean your Xcode downloads folder to reclaim some memory

I'm always looking for ways to reclaim space on my crammed hard disk. Thanks to the lovely JDiskReport, I've found a little directory where XCode stores the files it downloads when you choose to install components from the Preferences screen: /Users/<YourUser>/Library/Caches/com.apple.dt.Xcode. I wouldn't usually mess with this sort of internal caches, but in this case it looks like XCode won't remove old files after installing new ones: I had three .dmg files with different versions of Cli-Tools. I removed all .dmg files except latest version, and it doesn't look like I broke anything, so it's probably a safe trick. In my case, I claimed back some 250 MB -- not huge, but coupled with cleaning all caches for my secondary browsers (done from the proper UI), I got back about 1.5 GB today.

Apple Mail + Exchange WebServices = Madness

I bought my first Mac last year, and I've been using the default Mail client ever since. Despite all its shortcomings, it's one of the very few clients supporting Exchange, and probably the only one  I know (apart from Outlook) that supports even its WebService-mode my employer uses. OSX even supports shared calendars!

However, there is one particularly annoying problem I keep encountering.

Exchange has an "auto-discovery" feature, which means that you pass a web address to Mail, the app connects to that URL and it receives the addresses of all necessary servers involved. Say you are a responsible sysadmin, and you run TWO Exchange servers to get some redundancy; when Mail does the auto-discovery dance, it gets told that there are indeed two servers. Mail will try the first one, prompt the user for his credentials, and if successful, it will save server address and credentials in its settings and use it. When the first server goes down, it will switch to the second one, and the user will live happily ever after.

Now, OSX has a system-wide keychain for password storage; basically, applications store all passwords (and other securable objects) in a central, protected place in encrypted form. In order to discern which password is used by which app, they are organized in different "items" with name, description, etc.

It appears that Mail will write each server/user/pass combo in a different item. So when it connects to server1, it will create an item saying "for server 1, connect with username X and password Y"; when it connects to server2, even though it came from the same auto-discoverable Exchange setup, it will write a new item saying "for server2, connect with username X and password Y". When you change your password in Preferences, Mail will update only the last-used item. Which means, the next time you switch server, your authentication will fail at least once. It appears also that Calendar (or any other program using the accounts specified in System Preferences) will randomly pick one of the two.

If you also have the misfortune to install Outlook 2011 for Mac (which you might want to do because some niche Exchange features are not supported by Apple programs), that program will write yet another item.

The result: you have three items for one account -- and this doesn't even include other devices! (phone etc). Whenever your password changes, you have to make sure all of them are updated, or authentication will likely fail somewhere. Because these subsystems poll servers very frequently, and don't give up very easily when refused access, there is a very high chance that a password change will result in your apps triggering a lock-out by constantly trying to use the old password. This is what regularly happens to me! Note that simply changing your password in Preferences might not be enough, because Mail will update only one of the two items.

Workaround: turn off *all* your clients (quit Mail, Calendar, Outlook, shut down your iPhone etc), change the password on Exchange, then open the Keychain ( /Applications/Utilities/Keychain Access.app ), select Passwords, search your username and update all necessary items, then reboot for good measure. Now all apps will use the correct credentials, and not lock you out.