Web Application Proxy (WAP), is a remote access computer software feature in Windows Server 2012 R2. It replaced Microsoft Forefront Unified Access Gateway (UAG). WAP provides the reverse proxy capability that allows users outside a corporate network to access web applications hosting on the internal corporate network. WAP uses Active Directory Federation Services (ADFS) for pre-authenticated access to internally hosted corporate web applications such as SharePoint.
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Web Application Proxy Wikipedia(Text) CC BY-SA