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RE: [off-topic?] Chrooting ssh/telnet users?

There is a chroot patch for the potato openssh-1.2.3 source in /contrib
however it appears to be broken.

I have created a modified diff for the Debian package source which will
apply the patch correctly and build an ssh_1.2.3chroot1-9.3 package.

Email me if you would like the diff.

As has been well covered in this thread you will need to create a chroot
jail which has all the executables your chroot user requires as well as the
libraries the executables rely on.  There are many ways to acheive this.
For a very small chrooted environment (i.e. bash, cp, scp, ls, mv etc.) I
generally create this manually by copying the executables into the new
structure then running ldd on them to identify the libraries.

For a larger chroot environment you may want to look at dbootstrap.

You will have to manually maintain your chroot (upgrading
executables/security updates) unless you install APT into the chroot.  I
generally don't.

Andrew J. Stephen                               Phone  +64 4 496 4484 
Team Leader, Network Operations                 Mobile +64 25 582 304 
New Zealand Post                                Fax    +64 4 496 4914 
        "The important thing about standards is to have them."
         -- Bruce Schneier, creator of the Twofish algorithm  

> -----Original Message-----
> From: Javier Fernández-Sanguino Peña [mailto:jfs@computer.org]
> Sent: Saturday, 27 October 2001 02:15
> To: debian-security@lists.debian.org
> Subject: [off-topic?] Chrooting ssh/telnet users?
> I have been asked for this and I was trying to figure out how to do it
> (would document it later on in the Securing-Debian-Manual). So please,
> excuse me if you feel this is off-topic.
> The problem is, how can an admin restrict remote access from 
> a given user
> (through telnet and/or sshd) in order to limit his "moves" inside the
> operating system.
> Chrooting the daemon is a possibility, but it's not tailored 
> in a per-user
> basis but globally to all users (besides you need all the 
> tools that users
> might want to use in the jail). I'm looking more into a 
> jailed enviroment
> like proftpd's when you sed "DefaultRoot ~" (jails the user 
> into his home
> directory but he's able to use all commands, without having 
> to setup all
> the libraries in it).
> AFAIK, pam only allows to limit some user accesses (cores, memory
> limits..) not users "movement" in the OS
> 	Ideas?
> 	Regards
> 	Javi
> -- 
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