To ensure security and privacy for your users, and interoperability with Apple products, server administrators should use a group size of 2048 bits or greater when using Diffie-Hellman key exchange.
Services that might use these types of connections include:
- Enterprise Wi-Fi (802.1X)
- Secure email connections
- Secure web connections (HTTPS)
- Secure Internet printing (IPP over TLS/SSL)
iOS 8.4 and OS X v10.10.4 provide increased security against the "Logjam" vulnerability. After updating an iPhone, iPad, iPod touch, or Mac, these devices no longer connect to servers or webpages that are set up using weaker Diffie-Hellman encryption.
If your users can't establish a secure connection after updating, check the configuration of your server. Refer to these links for more information: