Leopard firewall scuppers Skype
Clash of closed software
CHECK ANOTHER mark up against Apple's Mac OS/X 10.5 Leopard release in the Not Ready For Prime Time column, this one for blocking the Skype VoIP and Chat application.
A post from Skype Staff member Ryan Hunt on the Skype Forums section for Mac OS/X 10.5 reads "Skype does not run when the built-in Firewall for MacOS is enabled." He goes on to suggest that it's really okay, because "The default configuration of MacOS 10.5 is to have the firewall off, so those who are using a standard install won't have any problems."
He says they're talking to Apple and working on a fix for the firewall blockage, but further suggests to users, "In the mean time, if you wish to use Skype, please disable the firewall."
One's hard pressed to decide who's lamer here -- Apple for releasing a mysteriously opaque, closed-source firewall that blocks outgoing connections on high-numbered ports, or Skype for recommending that Apple users disable their firewalls in order to keep using Skype.
What we have here is a clash of paranoid, proprietary software. Let Apple and Skype both keep their secrets from each other, and from their customers. A pox on both their houses. µ

Comments
Unless I'm criminally mistaken....
... Leopard still uses ipfw from BSD... The System Preferences are just ooey GUI candy on top of it..http://developer.apple.com/internet/security/securityintro.html
method of settlement!!
Please Look this site.Title is Skype on Leopard.
http://antiqblue.exblog.jp/
regard.
Self Modifying Applications
The issue is that Skype is doing something that applications should not be doing: modifying its own application bundle. See this article on the issue of code signing, self-modifying apps and the firewall:http://homepage.mac.com/simx/technonova/C488455530/E20071107233441/