坑爹的Apple網站資料和MDM廠商資料，大多數說iOS 7.x設備支持per app vpn了，但是沒有說明需要哪些系統環境要求。

1. iOS 7.x 設備，當然了

2. iOS 7.x 設備需在MDM服務器上注冊並接受管理（MDM服務器比如SAP Afaria（apple configurator可能也可以）可以下發專門的和per app vpn相關的MDM指令）

3.iOS 7.x 設備要安裝vpn的客戶端。啥？不是內置VPN支持了嗎？對比起，這個per app vpn需要iOS設備上面安裝特定VPN Client軟件啊

4. MDM服務器：MDM服務器比如SAP Afaria（apple configurator可能也可以）可以下發專門的和per app vpn相關的MDM指令

5.指定的VPN服務器，不多。啥？iOS設備支持的VPN不行？是滴，不是所有的都支持。

貌似Cisco AnyConnect, F5可以。

參考：

該文章介紹用AirWatch結合F5 SSL VPN配置per app vpn
The iOS Per app VPN uses F5’s APM SOCKS Proxy functionality so we'll need TMOS 11.4 or higher installed on the BIG-IP and Edge Client 2.0 or higher installed on the mobile device.
https://devcentral.f5.com/articles/solving-secure-mobile-access-with-f5-and-ios-7-per-app-vpn-part-2

SAP Afaria論壇中的帖子提到Cisco Anyconnect, F5支持Per App VPN，然後iOS設備內置的vpn client不支持這個特性
"Per App VPN" requires additional VPN software to be installed.
Mocana, Cisco Anyconnect, F5, etc can do Per App VPN. The built-in VPN client doesn't do per-app.
http://scn.sap.com/thread/3571739

某不知名的MDM廠商倒是明確說F5 Edge client and the Aruba VPN client支持per app vpn特性
I have applied a "Per app VPN" profile for iOS and deployed it. But the app does not use it. Why not?
The "Per app VPN" feature does not support the built-in VPN functionality as provided in iOS. Therefore, you cannot use this one.
What is required so successfully use it?
You must have installed a VPN client on the iOS device which supports the "Per app VPN" feature like the F5 Edge client.
If this is installed, you must deploy a VPN configuration for this client and in addition specify the VPN profile to be used by the app.
Which VPN Client does Sophos Mobile Control currently support?
As of now the only VPN client being supported is Cisco AnyConnect
Which VPN Clients do support the "Per app VPN" feature?
In december 2013 the only VPN clients supporting this feature are the F5 Edge client and the Aruba VPN client.
http://www.sophos.com/en-us/support/knowledgebase/120242.aspx

Setting Up an iOS 7 On-Demand VPN（貌似openvpn可能可以）
with IPSec(pserf) openvpn
http://www.derman.com/blogs/Setting-Up-iOS-OnDemand-VPN