help for a jailed user

[CAS_2]

Hi

I created a jailed user by the simplest way -- using restricted shell.
I also changed /etc/ftpd/ftpaccess in order to be a GUEST ftp user. So, its home directory is similar to

/dirA/./dirB

My problem is that I have to grant write permission for its home dir (/dirA/dirB) and this means the user can modify/delete its .profile file. Therefore, that user can edit its .profile and include a 'cd' command in it for jumping to any other directory in the tree (according to shell man pages, restrictions to shell are enforced AFTER reading user's .profile):

The restrictions above are enforced after the .profile and ENV files are interpreted.



Any other simple ideas ?

P.D: I decided to use restricted shell to prevent create a STRONG jailed user (using sudo and chroot)

[Steven E. Protter]

Shalom,

The user is not properly jailed if all the user can just modify his/her .profile and get out of jail.

You have changed ftp access, which is a good start. For FTP to work right in a chroot jail, a few binaries like ls need to be copied locally.

The user should NOT have write permission on .profile. The chroot commands and setup can be performed there. The user may need a normal shell to execute needed comands but if the user is in chroot without the ability to change .profile the user is stuck.

chroot doesn't work really well if the user needs to use applications that require access to the root of the system.

Secure shell and chroot environments:
http://docs.hp.com/en/T1471-90013/ch01s13.html
Chroot in general
http://unix.derkeiler.com/Mailing-Lists/HP-UX-Admin/2003-06/0034.html

It may seem complex, but its really not once you do it a few times.

SEP

[CAS_2]

You wrote
"The user should NOT have write permission on .profile"

I agree. This can be accomplised if owner is root, for example. But if user has permission to write in its home directory, it can delete the .profile owned by root and create a new one owned by him.

[TwoProc]

Restrict the permission to both the .profile and the home directory of the user - giving them read access to things only by access from a group that you create for the one user, then create a subdirectory called "data" or "docs" or "pub", etc., that they can rwx to via direct user ownership.

[Chan 007]

CAS,

Why not use acl...


Chan

[CAS_2]

ACL ?

What entries shoud I use ?