Annoying problem, but a problem I have been tasked to troubleshoot nonetheless. Some users behind our ISA 2006 Firewall use iTunes. Good for them. For the most part, iTunes works pretty decently. However, there is a certain functionality that is tripping up on the firewall, and I can't seem to figure it out.
The problem: a user connects their iPod to their iTunes and attempts to Restore it by connecting to the iPod Software Update Server to get the latest OS, and they get an error in the application. The error reads "The iPod software update server could not be contacted. An unknown error occurred (-23)." When watching the logging on the ISA server itself, the only log that shows a failure is this:
Obviously I have scoured the web for advice, and have come up empty-handed. I tried the advice given on isasmb.blogspot.com regarding compression, I have added the *.apple.com and *.edgesuite.net URLs to the DirectAccess tab, and I have also added an Access Rule allowing all protocols from all users in our Internal network to all iTunes associated URLs and IPs. The logged failure above even shows that this rule is picking up the traffic.
It appears that the iTunes Store is working, but certain functionality such as updating produces this error. Any thoughts or suggestions? I would really appreciate anything at all at this point!