[gentoo-dev] Suitable USE flag name for stuff that requires non volatile memory

[gentoo-dev] Suitable USE flag name for stuff that requires non volatile memory

[Roy Marples]

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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[gentoo-dev] Re: Suitable USE flag name for stuff that requires non volatile memory

[Duncan]

Roy Marples <uberlord@gentoo.org> posted
20070512001018.0eca154e@uberlaptop.marples.name, excerpted below, on  Sat,
12 May 2007 00:10:18 +0100:

> dhcpcd-3.1 is [...] almost ready to be put into the tree.  [N]ew
> feature[:] generates a DUID-LLT [which should persist] 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.

> It's also required for DHCP over infiniband and IPv6.
> 
> The big downside is that it does require non volative storage[.]
> Once you have a DUID, it should never change.

ipv6 USE flag, since IPv6 requires it?  It's not a perfect fit, but it's 
no worse than some others I've seen.  An elog could then be used with a 
short explanation and possibly a link to something a bit longer.  This 
works only if having it on by default is desired, since many profiles set 
+ipv6.

d-uid or dhcp-uid?  Unlike ipv6, this would be a local USE flag (as would 
be the parallel choices you suggested), so could be defaulted as desired, 
with a corresondingly less generic use.desc(.local) description.  An elog 
would then be optional.  UID should also have meaning to rather more 
users than duid does, and dhcp-uid would be quite descriptive at least to 
me, with or without additional information such as you provided above.

I like dhcp-uid, personally.  If that's Greek to someone, likely about 
anything else you chose would be as well, yet it still should make sense 
to anyone who has come across "UID" before.  For those to whom it doesn't 
make sense, the use.desc.local entry should hopefully be sufficient, if 
they even bother to worry about it as against the defaults, whatever they 
may be.

BTW, this is very useful information to me, and one of the big reasons 
I'm subscribed here, to get info such as this before I'm faced with it in 
the tree, and don't have a clue.  Thanks! =8^)

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman

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Re: [gentoo-dev] Suitable USE flag name for stuff that requires non volatile memory

[Mike Frysinger]

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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

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[gentoo-dev] Re: Suitable USE flag name for stuff that requires non volatile memory

[Duncan]

Mike Frysinger <vapier@gentoo.org> posted
200705120647.39160.vapier@gentoo.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.

(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.)

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman

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Re: [gentoo-dev] Re: Suitable USE flag name for stuff that requires non volatile memory

[Mike Frysinger]

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On Saturday 12 May 2007, Duncan wrote:
> Mike Frysinger <vapier@gentoo.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

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Re: [gentoo-dev] Suitable USE flag name for stuff that requires non volatile memory

[Carsten Lohrke]

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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

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Re: [gentoo-dev] Suitable USE flag name for stuff that requires non volatile memory

[Mike Frysinger]

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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

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Re: [gentoo-dev] Suitable USE flag name for stuff that requires non volatile memory

[Roy Marples]

On Sat, 12 May 2007 09:00:34 -0400
Mike Frysinger <vapier@gentoo.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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Re: [gentoo-dev] Re: Suitable USE flag name for stuff that requires non volatile memory

[Roy Marples]

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

> Mike Frysinger <vapier@gentoo.org> posted
> 200705120647.39160.vapier@gentoo.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-dev] Re: Suitable USE flag name for stuff that requires non volatile memory

[Duncan]

Roy Marples <uberlord@gentoo.org> posted
20070512161638.0bab56dc@uberlaptop.marples.name, excerpted below, on  Sat,
12 May 2007 16:16:38 +0100:

> 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.)
> 
> 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.  The -I <nothing> sounds like the better alternative, as from 
your description elsewhere removing the duid would simply create new ones 
each time, filling up the slots on the server unnecessarily, while the -I 
disabling shouldn't use the functionality at all, which would be the same 
as having it not compiled in.

With that caveat, having it on by default and the livecd thing turn it 
off seems a bit more reasonable -- except then the livecds won't of 
course work with ipv6 DHCP then, as it's required there.  Given limited 
space on the CD and a desire to use it on ipv6 nets, I don't see a way 
around disabling it there 200 uses filling up garbage slots on the server 
or not.  Well, there's a hack, two in-path versions, a normal version 
script stub that adds the appropriate deactivating -I and an ipv6 or 
whatever version that doesn't, but that's a hack and not really 
satisfactory.

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.

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.

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman

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Re: [gentoo-dev] Re: Suitable USE flag name for stuff that requires non volatile memory

[Roy Marples]

On Sat, 12 May 2007 17:36:28 +0000 (UTC)
Duncan <1i5t5.duncan@cox.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
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Re: [gentoo-dev] Suitable USE flag name for stuff that requires non volatile memory

[Mike Frysinger]

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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

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Re: [gentoo-dev] Suitable USE flag name for stuff that requires non volatile memory

[Roy Marples]

On Sun, 13 May 2007 17:44:28 -0400
Mike Frysinger <vapier@gentoo.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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Re: [gentoo-dev] Suitable USE flag name for stuff that requires non volatile memory

[Mike Frysinger]

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On Sunday 13 May 2007, Roy Marples wrote:
> Mike Frysinger <vapier@gentoo.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.

which is what i was referring to

if use livecd ; then
  <move dhcpcd to dhcpcd.real>
  <install wrapper script that executes `dhcpcd -I` as "dhcpcd">
fi
-mike

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[gentoo-dev] Re: Suitable USE flag name for stuff that requires non volatile memory

[Steve Long]

Mike Frysinger wrote:
> if use livecd ; then
>   <move dhcpcd to dhcpcd.real>
>   <install wrapper script that executes `dhcpcd -I` as "dhcpcd">
> fi
or even alias dhcpcd 'dhcpcd -l' (in bashrc? - could have a separate one for
root)


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Re: [gentoo-dev] Suitable USE flag name for stuff that requires non volatile memory

[Chris Gianelloni]

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On Sun, 2007-05-13 at 22:53 +0100, Roy Marples wrote:
> On Sun, 13 May 2007 17:44:28 -0400
> Mike Frysinger <vapier@gentoo.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.

First off, we have 100% control over the "root" and "gentoo"
environments on the release media.  You want a function called dhcpcd
that runs with -I on the LiveCD?  We can add that to root's .bashrc
easily on the CD.  It also wouldn't populate into the installed
environment, since we don't copy root's .bashrc as our default is to not
have one.

-- 
Chris Gianelloni
Release Engineering Strategic Lead
Alpha/AMD64/x86 Architecture Teams
Games Developer/Council Member/Foundation Trustee
Gentoo Foundation

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