Re: tlug: more starnge ISP behavior

["Stephen J. Turnbull" <turnbull@example.com>]

>>>>> "jdb" == J David Beutel <jdb@example.com> writes:

    jdb> On Tue, 20 Oct 1998, Jim Schweizer wrote:
    >> OK, this is getting wierder (or I'm losing my marbles.)

    jdb> Maybe they think some people have web pages that reference
    jdb> themselves using a URL, so they want to encourage people to
    jdb> update them?  Pretty weak, tho--people should not have such
    jdb> web pages.

Probably they threw out the old machines so they lost the pages.  :-)

    >> I have an account with one of the ISPs in question so I decided
    >> to dig around a little. I ftp'd to the new server and behold -
    >> they already set up a bin directory for me?! I wonder what's in
    >> it...
    >> 
    >> Wow, my very own ls....

    jdb> That's a pretty big ls.  Maybe it's output from ls -l,
    jdb> listing your previous files?  But then why is it
    jdb> execute-only, and in a bin directory?  Maybe it's a real,
    jdb> big, old ls sitting there for ftpd security?

The best way to be _sure_ of security in that kind of situation is to
do a chroot.  Can you do cd .. from your home directory under ftp?

But if you chroot somewhere that isn't /, and I can't see why you'd
chroot / :-), what goes wrong?  Well, you can't see /bin, /usr/bin,
and /lib, for starters.  (I'm sure it's possible to hardlink out of a
chroot, but you cannot symlink out.)  Since ls is executed as an
external process, you need a ls under the chroot, and it has to be
statically linked.

-- 
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