Migrating from 3.1.x to 4.1.0 (was: chroot issue)

[Niall O'Reilly]

	Some material for the search engines, based on my
	experience earlier today, when I finally got to upgrade
	the first of my boxes to 4.1.0.

On Fri, 2009-01-16 at 21:20 +0000, Maciej W. Rozycki wrote:
> # mount -t proc /proc /var/dhcp/proc
> or suchlike and you will be done.

	or just add an extra line in /etc/fstab:

proc  /var/dhcpd/proc  proc  defaults  0 0

	In fact, I tried 'ro' instead of 'defaults', in order
	to try to ensure that only the 'canonical' instance of 
	the filesystem was writeable.  No joy, both became RO, 
	and one or two sysctl changes required during system 
	startup failed, breaking IPv6 forwarding and thus radvd.
	Not good: the box is my home router as well as doing
	DHCP and other utility stuff.

	Ideally /proc/net should be scanned before the chroot
	(unless the --enable-early-chroot option is configured),
	but this doesn't happen.  Arguably, this is a bug.

	Apart from this, some defaults are different: classic
	IPv4 DHCP must be explicitly specified on the command
	line (option '-4'), and the leases file is no longer 
	expected where it used to be (option '-lf' with due
	care to chroot effects).

	On Red-Hat/Fedora systems, editing /etc/sysconfig/dhcpd
	is likely to be useful.  It will probably also help to have
	dedicated /etc/sysconfig/dhcpd-v6 and /etc/init.d/dhcpd-v6
	so as to keep the two DHCP services from tripping each other
	up.  So far, I haven't a need for the IPv6 flavour of DHCP.

 	With just the couple of work-arounds mentioned above, it all 
	seems to have 'just worked'.

	/Niall