[UPDATE june 2009: this is solved in WordPress 2.8]
Having a fair amount of experience with WordPress installations and configuration, I wanted to install trusty old WP 2.5.1 on an idle desktop (winXP+xampp) at work to do some blogging on our intranet. The installation itself went smoothly (how hard can unpacking a zip-file be) but after some time the damn thing stopped working, producing nasty timeout-errors caused by a.o. wp-includes/update.php and wp-admin/includes/update.php.
The problem is that WordPress tries to open an internet-connection (using fsockopen) to see if updates are available. Great, except when you’re trying to run WordPress on an intranet behind a proxy without a (direct) connection to the internet. After some unsuccessful fiddling in multiple WordPress php-files, I ended up disabling fsockopen in php.ini (disable_functions)!
Disabling! Fsockopen! In php.ini! Just to have a working WP?
I mean, come on guys, why doesn’t WordPress provide configuration options where you can specify if and how (what type of proxy, what address to find it on, …) it should try to connect to the internet? I even made this truly amazing UI mock-up which you guys can just like copy/paste straight into your code;
How should WordPress connect to the internet to check for updates?
(*) Direct connection to the internet (default)
( ) Use a proxy:
Proxy type: (*) http ( ) socks
Proxy URL: ___________________________________________
Proxy User: ___________________________________________ (optional)
Proxy Password: ___________________________________________ (optional)
( ) No internet connection available (WordPress won't be able
to warn you about updates!)