If you go to the http://archive.ubuntu.com/ubuntu/ site, and then just click multiple times on the ubuntu folder, it looks like you can't actually go into the folder. The exact same directory listing is still shown--and after every click on folder name, it will append another ubuntu/ to the URL shown in the address bar!

enter image description here

Is this a bug or a security feature?

up vote 15 down vote accepted

Neither. That's just the effect of a symbolic link that points to the current directory:

$ mkdir foo
$ ln -s . foo/foo
$ ls foo
foo
$ ls foo/foo
foo
$ ls foo/foo/foo
foo

It's purely for convenience of mirroring. Say we have a mirror http://my-mirror.com. It does not have to make a top-level ubuntu directory; it can simply mirror archive.ubuntu.com/ubuntu. Then, if you need to switch mirrors in /etc/apt/sources.list, you can directly swap archive.ubuntu.com with my-mirror.com.

  • It seems that it works up to 40 ubuntus, and then returns 403 for any more, an I right in assuming this is a symlink limit that is there to stop people sending near infinite amounts of ubuntus and DOSing the server? – jrtapsell Sep 6 '17 at 10:48
  • 9
    @jrtapsell that's probably due to this: unix.stackexchange.com/a/79576/70524 – muru Sep 6 '17 at 10:54
  • Ah, my google-fu was weak, that makes sense – jrtapsell Sep 6 '17 at 10:56

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