I've tried a lot of times to do a fresh installation of JForum 2.1.7 on my CentOS. I got the permission error on index.htm and WEB-INF/config directory should be writable requirement. Even when I chmod 777 on the whole jforum subdirectory. It still tell me the same permission error.
I recall that using http://host/jforum/install.jsp is from 2.1.7. And in the previous 2.1.6 there is an __index.redirect file. After downloading the source code. And I found that
Later, I upload the 2.1.6 version's __index.redirect file. The installation works now.
I think the install wizard need some fix on this...