User-Mode Linux Merged Into 2.5 Kernel

An anonymous reader writes "With little fanfare, User Mode-Linux (UML) has been merged into Linus' BitKeeper tree. The merge followed a patch by UML author Jeff Dike, resynching UML with the 2.5.34 development kernel. From the UML homepage, User-Mode Linux provides you with a virtual machine that offers 'a safe, secure way of running Linux versions and Linux processes. Run buggy software, experiment with new Linux kernels or distributions, and poke around in the internals of Linux, all without risking your main Linux setup.'" There's more UML resources available at the community site.

Comments

Good stuff.

[Lukey Boy]

I recently found a beautiful use for user mode linux - changing distributions with a minimum of downtime.

I have a RedHat box that's colocated that I wanted to move over to Debian - so I installed UML and loaded Debian onto one partition, got everything set up correctly and told LILO to boot off the new slice. After a few minutes of praying Debian came up running all the correct services.

Thanks to the UML team!

Re:Honeypot

[VC]

I just did this like 2 days ago. Im astounded that UML (bad name IMHO, been used already) is going into the main tree.
UML is awesome, dont just set up 1 honeypot, set up 5 let the hacker think theyve found a whole network..
Ive got my machine (no you cant have the IP ;-) so that ports 22 and 80 to to the *real* linux distro and all other exploitable ports goto my UML machine.
Except that ive got TCP wrappers set up so that when you connect to my virtual machine, it NMAPs you and logs it all to a file.
But probably the most fun thing you can do is test things like:

# rm -rf / ;-)

Vservers/ctx patch can do this without overhead

[jelle]

Somebody has to mention the Virtual Private Servers (vservers) and security contexts (ctx) patch, which takes chroot(), and adds the good stuff from jail() and more to make completely separated contexts for process groups, without the overhead of another kernel.

I've been running Debian 2.2r7 and RedHat7.2 in parallel with Debian/Woody on the same box for months now with this patch.

Another important use

[fireboy1919]

There are several products that require a custom kernel, and this could certainly benefit all of them.

The one I'm thinking of right now is Win4lin, the cheapest, fastest Windows VM for Linux right now; it needs a kernel with its own patches, and they distribute patches for Debian, Slackware, Mandrake, and Vanilla kernels. My distro (Gentoo) makes a kernel which is known for its speed, but which I'm not using right now because of this (I can't even patch the Vanilla kernel to that level because it the Win4lin patch conflicts with Gentoo's patches).