There are the following symptoms when Single Sign-On works correctly for Subversion clients while Internet Explorer continues to prompt users for their credentials:
- Integrated Windows Authentication is enabled in VisualSVN Server.
- Users can access VisualSVN Server repositories using Subversion clients (such as svn.exe or TortoiseSVN) without being prompted for username and password.
- Users are prompted for username and password when they access VisualSVN Server repositories using Internet Explorer.
In most cases, this problem is caused by the fact that Internet Explorer doesn't recognize URL of your VisualSVN Server as a local intranet site. For security reasons, Internet Explorer automatically sends user's credentials only to local intranet sites.
If the computer name portion of the requested URL contains periods (such as http://svn.example.com or http://10.0.0.1), Internet Explorer assumes that the requested address exists on the Internet and does not pass any credentials automatically.
In other words, if you access VisualSVN Server using Fully Qualified Domain Name (FQDN) or IP address, the server will not be detected as a local intranet site and Single Sign-On will be prohibited by Internet Explorer.
Addresses without periods (such as http://svnserver) are considered to be on the local intranet and Internet Explorer passes credentials automatically. The only exception is addresses included in the Intranet zone in Internet Explorer.
Other possible causes of this problem are described in the related Microsoft's article: Internet Explorer May Prompt You for a Password
If you access VisualSVN Server using Fully Qualified Domain Name (FQDN) or IP address, it's recommended to explicitly add the address of the VisualSVN Server to the Intranet zone in Internet Explorer or using Group Policies.
Possible ways to add site to the Intranet Zone in Internet Explorer are described in the related Microsoft's article: Intranet site is identified as an Internet site when you use an FQDN or an IP address.