[834] in linux-security and linux-alert archive
Re: [linux-security] Talk security?
daemon@ATHENA.MIT.EDU (Vaughn Skinner)
Fri Jun 21 12:05:28 1996
Date: Mon, 17 Jun 1996 13:40:30 -0700
From: Vaughn Skinner <vaughn@solid.net>
To: linux-security@tarsier.cv.nrao.edu
In-reply-to: <11350.199606162322@stone.dcs.warwick.ac.uk> (message from Zefram
on Mon, 17 Jun 1996 00:22:28 +0100 (BST))
[Mod: Quoting trimmed. --Jeff.]
The most obvious thing /etc/shells is used for is nonymous ftp. You
probably don't want to allow ftp access to this account. If you do,
things get a lot more complicated. But don't forget that it's used by
other programs too; for example, GNU su (a security hole in itself, for
obvious reasons) allows the user to run an arbitrary program instead of
the target user's login shell, if the target user is an unrestricted
account (login shell in /etc/shells).
So, to summarise, *don't* put an insecure program in a privileged
position, and *don't* list a restricted shell as unrestricted.
-zefram
(I eat my humble pills...)
If it is a bad idea to put /bin/ftponly in /etc/shells, I need
a new way to allow users to have ftp access without shell access.
wu.ftpd requires the user's shell to be in /etc/shells.
Is the solution a ftpd hack to accept /bin/ftponly as a valid
shell? Is there a better way?
vaughn
