Suitable USE flag name for stuff that requires non volatile memory

Hi List!

dhcpcd-3.1 is making good progress and is almost ready to be
put into
the tree. One of it's new features is that it generates a
DUID-LLT.
This has to be stored in non volatile storage, so it
persists across
reboots. I would like a nice USE flag name, so it can be
compiled with
or without that support. My ideas so far.

duid
duid-llt
(both descriptive, but doesn't actually mean anything to
most users)

livecd
(only a livecd is volative, even embedded devices have non
volative
storage)

volatile

More are welcome 

For those that are interested in what a DUID is, read on. A
DUID (DHCP
Unique IDentifier) is a unique identifier to the machine
that should
never change and is used along with an IAID (Identity
association
identifier). Simply put its a means of identifying the
machine and the
interface. The DHCP specification allowed >1 interface
per machine, but
with the advent of dynamic DNS it's near impossible to match
machines
and interfaces reliably. This allows just that so in the
future servers
can get a list of IP's for a name instead of just the
last/first one in.

It's also required for DHCP over infiniband and IPv6.

The big downside is that it does require non volative
storage or you
could get a big long list because ...... interfaces can be
changed into
other machines, so part of the DUID is a time stamp. Once
you have a
DUID, it should never change.

Of course, the RFC's that define all this seem to have
forgotten about
dual booting different OS's, but that's not our problem 

Thanks

Roy
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On Friday 11 May 2007, Roy Marples wrote:
> livecd
> (only a livecd is volative, even embedded devices have
non volative
> storage)

i would use that myself ... perhaps even tie in USE=netboot
...
-mike

ON SATURDAY 12 MAY 2007, DUNCAN WROTE:
> MIKE FRYSINGER <VAPIERGENTOO.ORG> POSTED
> > ON FRIDAY 11 MAY 2007, ROY MARPLES WROTE:
> >> LIVECD
> >> (ONLY A LIVECD IS VOLATIVE, EVEN EMBEDDED
DEVICES HAVE NON VOLATIVE
> >> STORAGE)
> >
> > I WOULD USE THAT MYSELF ... PERHAPS EVEN TIE IN
USE=NETBOOT ...
>
> EXCEPT THAT LIVECD IS ENTIRELY UNSUITABLE.  THE
DESCRIPTION SAYS IT'S FOR
> INTERNAL USE ONLY, NOT TO BE SET ON A STANDARD
INSTALLATION, WHILE ROY'S
> POST SPECIFICALLY STATED THAT THOSE MERGING THE PACKAGE
FOR USE ON IPV6
> WILL PROBABLY WANT THE FUNCTIONALITY ON.

AND ROY'S DESCRIPTION OF THE FLAG SOUNDS LIKE IT'S ONE YOU
SHOULDNT BE 
DISABLING IN GENERAL SO IT ALIGNS WITH OUR INTERNAL USAGE
-MIKE

Does it matter that the DUID-LLT isn't stored when starting
from a Live-CD? I 
don't see why there is the need for a use flag for this
functionality, when 
it doesn't imply a new dependency.


Carsten

On Saturday 12 May 2007, Carsten Lohrke wrote:
> Does it matter that the DUID-LLT isn't stored when
starting from a Live-CD?
> I don't see why there is the need for a use flag for
this functionality,
> when it doesn't imply a new dependency.

the concern was to have a way to provide "nice"
clients for use on volatile 
systems (netboot/livecd/etc...)

everytime you'd boot up such a system and do dhcp, you'd
create a new unique 
id and the server would store it ... this isnt very nice to
the server admin 
who now has a set of unique ids that will never be utilized
again but by 
default would maintain all of them
-mike

On Sat, 12 May 2007 09:00:34 -0400
Mike Frysinger <vapiergentoo.org> wrote:

> On Saturday 12 May 2007, Carsten Lohrke wrote:
> > Does it matter that the DUID-LLT isn't stored when
starting from a
> > Live-CD? I don't see why there is the need for a
use flag for this
> > functionality, when it doesn't imply a new
dependency.
> 
> the concern was to have a way to provide
"nice" clients for use on
> volatile systems (netboot/livecd/etc...)
> 
> everytime you'd boot up such a system and do dhcp,
you'd create a new
> unique id and the server would store it ... this isnt
very nice to
> the server admin who now has a set of unique ids that
will never be
> utilized again but by default would maintain all of
them
> -mike

Not only that, but boot of the same computer using a CD 200
times and
you use up 200 leases. Nice DOS attack I'd like to avoid
really 

I've thought long and hard about it and I think a compile
time option
is best here. You can still disable the usage of DUID by
null arg to
the -I option, but many users launch dhcpcd by hand on the
live cds.

Thanks

Roy
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gentoo-devgentoo.org mailing list

On Sat, 12 May 2007 11:34:10 +0000 (UTC)
Duncan <1i5t5.duncancox.net> wrote:

> Mike Frysinger <vapiergentoo.org> posted
> 200705120647.39160.vapiergentoo.org, excerpted
below, on  Sat, 12 May
> 2007 06:47:38 -0400:
> 
> > On Friday 11 May 2007, Roy Marples wrote:
> >> livecd
> >> (only a livecd is volative, even embedded
devices have non volative
> >> storage)
> > 
> > i would use that myself ... perhaps even tie in
USE=netboot ...
> 
> Except that livecd is entirely unsuitable.  The
description says it's
> for internal use only, not to be set on a standard
installation,
> while Roy's post specifically stated that those merging
the package
> for use on IPv6 will probably want the functionality
on.

Although it's a requirement for IPv6 DHCP, it's recommended
for IPv4
these days too. It is a requirement for IPv4 DHCP over
infiniband as
that has MAC address sizes that are great than what DHCP
messages
originally allowed. So no, in this case the ipv6 USE flag
would be bad
for this. I also implies IPv6 support which it won't have
for some time
yet.

> (I OTOH, would want it off, for the same reason I'm
running the 
> macchanger module, have cookies off by default, and
block the likes
> of doubleclick.  I like my IP address actually changing
once in
> awhile, certainly more frequently than my ISP tends to
change it
> given the same MAC address every time.  My ISP may be
able to
> associate my IP with my name and account based on the
records for the
> cable modem registered in my name, but that doesn't
mean I want every
> doubleclick and google.com doing it, at least not
without going to a
> bit of trouble.  Thus, using a non-transparent flag
such as livecd
> and defaulting it to on, or simply hard-deping it,
isn't a
> particularly nice option either.)

You can disable it's use at runtime by giving the -I option
a null
argument. This is unsuitable for live cd users as they won't
do that by
default.

Or you can always remove the file
/var/lib/dhcpcd/dhcpcd.duid and it
will make a new one for you.

Thanks

Roy
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gentoo-devgentoo.org mailing list

On Sat, 12 May 2007 17:36:28 +0000 (UTC)
Duncan <1i5t5.duncancox.net> wrote:
> Are any other LiveCDs using it yet or otherwise
providing IPv6 DHCP 
> functionality?  What do they do?  Surely it's not just
a Gentoo
> problem.

There's only one dhcp IPv6 client, and thats dhcpv6 which
hasn't been
updated for a while and is quite crufty. They force a
duid-llt too.

DHCP IPv6 isn't commonplace, as I don't think there's any
good servers
yet. ISC's DHCP will have IPv6 support at some point
though.

But you can configure pretty much everything automatically
using radvd
except for things like DNS resolution, NTP, etc.


> I still think IUSE=dhcp-uid is about as descriptive as
it gets, and 
> coupled with a decent use.desc.local entry and perhaps
an elog notice
> of some sort, that should be fine.

Noted.

Thanks

Roy
-- 
gentoo-devgentoo.org mailing list

On Saturday 12 May 2007, Roy Marples wrote:
> I've thought long and hard about it and I think a
compile time option
> is best here. You can still disable the usage of DUID
by null arg to
> the -I option, but many users launch dhcpcd by hand on
the live cds.

hmm, you can do it at runtime ?  then you could provide a
wrapper based on 
USE=livecd that calls dhcpcd with the proper arguments ...
-mike

On Sun, 13 May 2007 17:44:28 -0400
Mike Frysinger <vapiergentoo.org> wrote:

> On Saturday 12 May 2007, Roy Marples wrote:
> > I've thought long and hard about it and I think a
compile time
> > option is best here. You can still disable the
usage of DUID by
> > null arg to the -I option, but many users launch
dhcpcd by hand on
> > the live cds.
> 
> hmm, you can do it at runtime ?  then you could provide
a wrapper
> based on USE=livecd that calls dhcpcd with the proper
arguments ...
> -mike

Yes, the net scripts could use -I if $CDBOOT is set, but I'm
thinking
about the user running it by hand here.

Roy
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