Question

I have a question regarding regarding the permissions. I believe that the 3 marks stand for owner group all. So I think that any user who will view my page will be the 3rth mark in the chmod command. However when I set a file to 700 which should be owner – all / group nothing / world-nothing. everyone can still see the file when they open the website. But when i set the permissions to 000 the file no longer opens so Im wondering how the permissions work.

Thanks

Answer 1

It is the web server process user (e.g. the user running Apache or whatever) for which permission checks are applied.

Presumably the web server user owns the files being served.

People visiting your website are not “users” of the system at all, in the sense of file system security. Rather, the web server process runs as a user of the system and serves up HTML on behalf of people requesting it.

UPDATE

Regarding your comment about the differences between 400, 700 and 755:

• Only the first digit matters if the process running the web server owns the file being served
• That means we really care about the difference between 4xx and 7xx
• Refer to the following table to understand what the “4” and the “7” mean

Permission Table

Nr  Permission        rwx
7   full              111
6   read and write    110
5   read and execute  101
4   read only         100
3   write and execute 011
2   write only        010
1   execute only      001
0   none              000

http://en.wikipedia.org/wiki/Chmod

Note that a “4” gives read access to the file owner and 7 gives full access (which includes read access).