[uml-devel] uml_utilities_20020212

[Jeff D. <jd...@ka...>]

There are two major changes in this update:

uml_mconsole now looks for its pipe in $HOME/.uml/<umid> by default.  It will
still look in /tmp/uml/<umid> for compatibility with older UMLs.

tunctl is a new tool for making TUN/TAP interfaces persistent and 
non-persistent.  The deal with this is that it allows the host sysadmin to
preconfigure a tap device for use by a particular user.  That user may
open and use the device, but may not change any aspects of the host side
of the interface.  This also means that use of uml_net is not required
in order for a non-privileged user to set up networking.

It has a dead simple interface:
	tunctl <uid> - creates a new tap device for use by user <uid>
	tunctl -nopersist <dev> - makes <dev> non-persistent

To use it, create the interface for the user:
	% sudo tunctl 500
	Set 'tap1' persistent and owned by uid 500

Configure it:
	sudo ifconfig tap1 192.168.0.254 up
	sudo route add -host 192.168.0.253 dev tap1
	sudo bash -c 'echo 1 > /proc/sys/net/ipv4/conf/tap1/proxy_arp'
	sudo arp -Ds 192.168.0.253 eth0 pub

is how I'm doing it.  Change IP addresses and stuff to suit.

Then run UML as that uid (you'll need 2.4.17-11 or later) with 
'eth0=tuntap,tap1'.  The presence of the device name tells the driver to 
open the preconfigured device and not to run uml_net for anything.

As a side-effect of this, changing the IP address of the UML side of the
interface won't work (the address can change, but packets won't reach it
any more).  This is a feature.

In order to get rid of the device:
	tunctl -nopersist tap1

There were also some Makefile cleanups which allow the install directories
to be specified on the make command line and some miscellaneous fixes in
uml_mconsole and uml_switch.

				Jeff