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* [gentoo-user] Be careful when using dhcp with a LiveCD
@ 2007-12-06 23:04 Grant
  2007-12-06 23:19 ` Mick
  0 siblings, 1 reply; 8+ messages in thread
From: Grant @ 2007-12-06 23:04 UTC (permalink / raw
  To: Gentoo mailing list

I just spent a few hours trying to fix a problem where my Gentoo
router would only dhcp the ip address of the cable modem instead of
the proper IP address from the WAN.  I ended up enabling USE=vram and
it worked again.

# equery uses dhcpcd
 + + vram : Disable DUID due to volatile media, such as a LiveCD

I had just previously booted to a Damn Small Linux LiveCD when the
trouble started so I'm thinking the CD tried to dhcp from my cable
internet provider without a DUID which caused the provider to change
something which means that I need to disable the DUID from now on?
It's confusing but that's the best I can come up with.

The point is: be careful when using dhcp from a LiveCD.  Your system
might act differently the next time you boot the hard drive.

- Grant
-- 
gentoo-user@gentoo.org mailing list



^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [gentoo-user] Be careful when using dhcp with a LiveCD
  2007-12-06 23:04 [gentoo-user] Be careful when using dhcp with a LiveCD Grant
@ 2007-12-06 23:19 ` Mick
  2007-12-07  0:05   ` Grant
  2007-12-07  1:21   ` b.n.
  0 siblings, 2 replies; 8+ messages in thread
From: Mick @ 2007-12-06 23:19 UTC (permalink / raw
  To: gentoo-user

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On Thursday 06 December 2007, Grant wrote:
> I just spent a few hours trying to fix a problem where my Gentoo
> router would only dhcp the ip address of the cable modem instead of
> the proper IP address from the WAN.  I ended up enabling USE=vram and
> it worked again.
>
> # equery uses dhcpcd
>  + + vram : Disable DUID due to volatile media, such as a LiveCD
>
> I had just previously booted to a Damn Small Linux LiveCD when the
> trouble started so I'm thinking the CD tried to dhcp from my cable
> internet provider without a DUID which caused the provider to change
> something which means that I need to disable the DUID from now on?
> It's confusing but that's the best I can come up with.
>
> The point is: be careful when using dhcp from a LiveCD.  Your system
> might act differently the next time you boot the hard drive.

The dhcpcd was changed recently and not all dhcp servers take kindly to it, 
when it uses DUID the way it does (some servers depend on DUID passing on to 
them the MAC of the client).  The solution I also found was to set the vram 
flag.
-- 
Regards,
Mick

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^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [gentoo-user] Be careful when using dhcp with a LiveCD
  2007-12-06 23:19 ` Mick
@ 2007-12-07  0:05   ` Grant
  2007-12-07  1:21   ` b.n.
  1 sibling, 0 replies; 8+ messages in thread
From: Grant @ 2007-12-07  0:05 UTC (permalink / raw
  To: gentoo-user

> > I just spent a few hours trying to fix a problem where my Gentoo
> > router would only dhcp the ip address of the cable modem instead of
> > the proper IP address from the WAN.  I ended up enabling USE=vram and
> > it worked again.
> >
> > # equery uses dhcpcd
> >  + + vram : Disable DUID due to volatile media, such as a LiveCD
> >
> > I had just previously booted to a Damn Small Linux LiveCD when the
> > trouble started so I'm thinking the CD tried to dhcp from my cable
> > internet provider without a DUID which caused the provider to change
> > something which means that I need to disable the DUID from now on?
> > It's confusing but that's the best I can come up with.
> >
> > The point is: be careful when using dhcp from a LiveCD.  Your system
> > might act differently the next time you boot the hard drive.
>
> The dhcpcd was changed recently and not all dhcp servers take kindly to it,
> when it uses DUID the way it does (some servers depend on DUID passing on to
> them the MAC of the client).  The solution I also found was to set the vram
> flag.

Something must have changed on my ISP's end when my router tried to
dhcp via the Damn Small Linux LiveCD.  It had been running dhcp just
fine ever since I switched to this ISP (Cox) and failed every time
after I booted that LiveCD until I enabled vram.

- Grant
-- 
gentoo-user@gentoo.org mailing list



^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [gentoo-user] Be careful when using dhcp with a LiveCD
  2007-12-06 23:19 ` Mick
  2007-12-07  0:05   ` Grant
@ 2007-12-07  1:21   ` b.n.
  2007-12-07  8:59     ` Mick
  1 sibling, 1 reply; 8+ messages in thread
From: b.n. @ 2007-12-07  1:21 UTC (permalink / raw
  To: gentoo-user

Mick ha scritto:
>> The point is: be careful when using dhcp from a LiveCD.  Your system
>> might act differently the next time you boot the hard drive.
> 
> The dhcpcd was changed recently and not all dhcp servers take kindly to it, 
> when it uses DUID the way it does (some servers depend on DUID passing on to 
> them the MAC of the client).  The solution I also found was to set the vram 
> flag.

I'm really ignorant on networks. What has changed on the dhcp side so
that *client* behaviour alters *server* behaviour? Isn't this horribly
broken (from the server side), or there is some reason to behave that?

m.
-- 
gentoo-user@gentoo.org mailing list



^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [gentoo-user] Be careful when using dhcp with a LiveCD
  2007-12-07  1:21   ` b.n.
@ 2007-12-07  8:59     ` Mick
  2007-12-07 16:39       ` Billy Holmes
  0 siblings, 1 reply; 8+ messages in thread
From: Mick @ 2007-12-07  8:59 UTC (permalink / raw
  To: gentoo-user

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On Friday 07 December 2007, b.n. wrote:
> Mick ha scritto:
> >> The point is: be careful when using dhcp from a LiveCD.  Your system
> >> might act differently the next time you boot the hard drive.
> >
> > The dhcpcd was changed recently and not all dhcp servers take kindly to
> > it, when it uses DUID the way it does (some servers depend on DUID
> > passing on to them the MAC of the client).  The solution I also found was
> > to set the vram flag.
>
> I'm really ignorant on networks. What has changed on the dhcp side so
> that *client* behaviour alters *server* behaviour? Isn't this horribly
> broken (from the server side), or there is some reason to behave that?

I am no less ignorant I'm afraid, but this is how I understand it in simple 
terms:

net-misc/dhcpcd-3.1.5-r1 has introduced a usage of DUID which is compliant 
with RFC 4361, and creates a client ID (this can be any string uniquely 
identifying the client interface).  However, a number of DHCP server 
implementations expect the DUID to contain the MAC of the client and unless 
this is in a particular format the server falls over.

The vrm flag allows the MAC to be used in the DUID field and then the server 
is happy to issue an IP address to the client.  As an alternative one can try 
the dhcpcd -I option to specify the MAC of the client, but when I tried it I 
couldn't get it to work.

I guess eventually all dhcp implementations will catch up with this change, 
although for now it is bound to create some problems with particular DHCP 
servers (cisco being one of them).  On the other hand RFC 4361 may be 
superseded/reversed, dhcpcd will go back to how it was and the world will be 
a simpler place to live and network.  :)

HTH.
-- 
Regards,
Mick

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^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [gentoo-user] Be careful when using dhcp with a LiveCD
  2007-12-07  8:59     ` Mick
@ 2007-12-07 16:39       ` Billy Holmes
  2007-12-07 18:43         ` Mick
  2007-12-07 20:34         ` Håkon Alstadheim
  0 siblings, 2 replies; 8+ messages in thread
From: Billy Holmes @ 2007-12-07 16:39 UTC (permalink / raw
  To: gentoo-user


> I guess eventually all dhcp implementations will catch up with this change,
> although for now it is bound to create some problems with particular DHCP

You could try disconnecting your cable modem for about 10 minutes,  
ensuring the ISP recognizes that it's offline, and thus remove the  
entries in it's DHCP table for your connection.

then when you boot your system normally, it might work like it used to.

-- 
gentoo-user@gentoo.org mailing list



^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [gentoo-user] Be careful when using dhcp with a LiveCD
  2007-12-07 16:39       ` Billy Holmes
@ 2007-12-07 18:43         ` Mick
  2007-12-07 20:34         ` Håkon Alstadheim
  1 sibling, 0 replies; 8+ messages in thread
From: Mick @ 2007-12-07 18:43 UTC (permalink / raw
  To: gentoo-user

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On Friday 07 December 2007, Billy Holmes wrote:
> > I guess eventually all dhcp implementations will catch up with this
> > change, although for now it is bound to create some problems with
> > particular DHCP
>
> You could try disconnecting your cable modem for about 10 minutes,
> ensuring the ISP recognizes that it's offline, and thus remove the
> entries in it's DHCP table for your connection.
>
> then when you boot your system normally, it might work like it used to.

The OP probably has a cable problem where this suggestion may apply.  In my 
case I was having problems with a local dhcp server on my LAN.  Nothing would 
get going, other than recompiling dhcpcd with vram set as a USE flag.
-- 
Regards,
Mick

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^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [gentoo-user] Be careful when using dhcp with a LiveCD
  2007-12-07 16:39       ` Billy Holmes
  2007-12-07 18:43         ` Mick
@ 2007-12-07 20:34         ` Håkon Alstadheim
  1 sibling, 0 replies; 8+ messages in thread
From: Håkon Alstadheim @ 2007-12-07 20:34 UTC (permalink / raw
  To: gentoo-user

Billy Holmes wrote:
>
>> I guess eventually all dhcp implementations will catch up with this 
>> change,
>> although for now it is bound to create some problems with particular 
>> DHCP
>
> You could try disconnecting your cable modem for about 10 minutes, 
> ensuring the ISP recognizes that it's offline, and thus remove the 
> entries in it's DHCP table for your connection.
>
> then when you boot your system normally, it might work like it used to.
>
Yes, that sound reasonable. The livecd was probably shut down without 
releasing the lease on the ip-address. Check the manual page on the 
dhcp-client on the live cd. There is probably some signal you can send 
it to make it release its lease.

When the regular os comes back up in this situation, it wants /its/ old 
ip back. This might hang on a server restriction on only one ip per 
subscriber/mac address, or it might just trigger a bug somewhere.

-- 
gentoo-user@gentoo.org mailing list



^ permalink raw reply	[flat|nested] 8+ messages in thread

end of thread, other threads:[~2007-12-07 20:44 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2007-12-06 23:04 [gentoo-user] Be careful when using dhcp with a LiveCD Grant
2007-12-06 23:19 ` Mick
2007-12-07  0:05   ` Grant
2007-12-07  1:21   ` b.n.
2007-12-07  8:59     ` Mick
2007-12-07 16:39       ` Billy Holmes
2007-12-07 18:43         ` Mick
2007-12-07 20:34         ` Håkon Alstadheim

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