Configure your security software
After updating your security software, configure it correctly to allow iTunes to contact Apple. The steps used to properly configure the security software will vary, and to find the exact steps, visit the manufacturer's support website or otherwise contact them for assistance.
Useful information for configuring your security software:
IMPORTANT: iTunes must be allowed to contact Apple using the following ports and servers:
- port 80
- port 443
For a more complete list of ports used by Apple products see "Well known" TCP and UDP ports used by Apple software products.
iTunes also contacts VeriSign servers during an iPhone restore and activation: