5.1. Symbolic links

We can now see the index.html file as expected but if we create a symbolic link called main.html to index.html and ask for that we get a failure.

$ cd /srv/www/WWW/
$ ln -s index.html main.html
$ ls -l
ls -l
total 4
-rw-r--r-- 1 root www-admin 306 2007-02-21 17:34 index.html
lrwxrwxrwx 1 root www-admin  10 2007-02-21 18:36 main.html -> index.html

When we try to access the symbolic link we get a 403 "Forbidden" error. The web server has found the symbolic link but has decided not to follow it.

To instruct the web server to follow symbolic links we need to set an option. You will recall we unset all options with Options None in the configuration file. Now we need to turn on one of them.

We can do this with the command Options FollowSymLinks but this has a certain subtly we need to understand. The command Options FollowSymLinks sets the FollowSymLinks option and unsets all of the others. The Options command followed by a list of options is absolute; precisely the options specified will be set and no others. For this reason we will introduce the syntax for setting (and unsetting) individual options while leaving the others unchanged.

Options  +FollowSymLinks

There is an analogous syntax with a minus sign for turning off options while leaving others untouched.

Because symbolic links might be used to circumvent access controls in the web server there is a modified version of this option with the rather unwieldy name SymLinksIfOwnerMatch. This instructs the web server to follow the symbolic link if and only if the symbolic link's owner (typically the user who created it) and the target's owner match.

It is worth mentioning that effects very similar to those provided by symlinks can also be created using web server facilities by using the Alias command which we cover later in Section 6.3.2. Both have strengths and weaknesses; using both at the same time can be a recipe for madness!