To host in IIS 7.5, and allow ".unity3d" to be downloaded is not an issue, what you need to add is new MIME, as explain here.
Easy, huh? I thought so. Then I browse to my page.
HTTP Error 401.3 - Unauthorized
You do not have permission to view this directory or page because of the access control list (ACL) configuration or encryption settings for this resource on the Web server.
I just did what's considered normal process, right? As rushing for live, I was cracking my head and wonder what went wrong. Goggling on internet gave me no result which could link error 401.3 with Unity web player. After few hours of trial-and-error, 2 workarounds came into my mind:
1) Permissions and user rights : I have tried to give full-rights on the folder, but failed.
2) Thinking to write code on Asp.net Impersonation, but it invites security concerns.
Suddenly, I found something special:
Hey, why the file name is in green color?
And another googling on this, I found out that:
Green means encrypted, blue means compressed in Windows.
The resolution is:
1) Right-click the file, click "Properties"
2) Click the "Advanced.." button.
3) On the "Compress or Encrypt attributes" section, un-check the "Encrypt contents to secure data"
After the decryption, the text becomes normal black color.
And refresh the browser again, it's ok.
I found out that:
1) when i uploaded the zipped content thru' FileZilla, then this encryption will happen. It must be caused by the FTP issue.
2) when i uploaded the extracted content thru' FileZilla, no issue.