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Bug 477356 - net-misc/dhcpcd-5.99.7 - option "duid" sends IPv6 info regardless of server protocol (IPv4)
Summary: net-misc/dhcpcd-5.99.7 - option "duid" sends IPv6 info regardless of server p...
Status: RESOLVED FIXED
Alias: None
Product: Gentoo Linux
Classification: Unclassified
Component: [OLD] Core system (show other bugs)
Hardware: AMD64 Linux
: Normal normal (vote)
Assignee: William Hubbs
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2013-07-19 07:07 UTC by Stefan Mosoi
Modified: 2014-02-20 09:22 UTC (History)
3 users (show)

See Also:
Package list:
Runtime testing required: ---


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Description Stefan Mosoi 2013-07-19 07:07:09 UTC
"Use the same DUID + IAID as set in DHCPv6 for DHCPv4 ClientID as per RFC4361."

The option "duid" should not be activated by default. 

It makes dhcpcd to send the wrong MAC address who breaks almost every installation of Gentoo in a network who uses MAC related security / access as it sends the IPv6 mac regardless of the protocol used by the dhcp server.
Comment 1 William Hubbs gentoo-dev 2013-07-19 15:22:32 UTC
Roy,

I'm curious why duid is enabled in the default configuration file when
the man page says it is disabled by default?

From this bug it sounds like it might be better to disable it in the
configuration file.

What do you think?
Comment 2 Roy Marples 2013-07-19 21:19:42 UTC
DUID is a requirement of DHCPv6. Clarified a little here.
http://roy.marples.name/cgi-bin/gitweb.cgi?p=dhcpcd.git;a=commitdiff;h=6bcd47080b0567af6a541986f88f0064728bf7e3

From RFC2131, DHCPv4, the clientid is supposed to be opaque and as such not translated in any way or form.
Plus, the MAC address for ethernet is sent in the chaddr field.

As to why it's now enabled by default, please read RFC4361.
http://www.ietf.org/rfc/rfc4361.txt

Using dhcpcd-6 and duid + ISC dhcpd server, configuration by hardware address works fine.
Comment 3 Stefan Mosoi 2013-07-22 10:08:52 UTC
The dhcp server in my network didn't recognize the network address. Instead of IPv4 mac XX:XX:XX:XX:XX:XX it sent the IPv6 (40 chars MAC) which the server didn't recognize. If this is the default config then at least put a warning so others know that it may cause problems with certain dhcp servers / configurations.
Comment 4 Roy Marples 2013-07-22 19:48:05 UTC
If you enable debug in dhcpcd, it does tell you what the client ID is going to be.

If you want more warning, modify the ebuild I guess, or maybe a news item.

Just a minor nitpick - DUID is not IPv6 specific and dhcpcd has had the option for years, just not on by default.
Comment 5 William Hubbs gentoo-dev 2013-08-02 22:16:15 UTC
I have added messages to the ebuild for dhcpcd-6.0.5.
Comment 6 vltg0903 2014-02-19 19:05:40 UTC
Hi,

I've just been bit by this particular bug, i. e. dhcpcd-5.6.4 gets me a lease in my university network with MAC access controls, dhcpcd-6.2.0 does not. Is there a way to force dhcpcd _not_ to transmit this DUID thingy? If not, is there any chance of a noduid option in a future version?

Cheers,

Andreas
Comment 7 Roy Marples 2014-02-20 09:22:11 UTC
(In reply to Andreas Eckstein from comment #6)
> Hi,
> 
> I've just been bit by this particular bug, i. e. dhcpcd-5.6.4 gets me a
> lease in my university network with MAC access controls, dhcpcd-6.2.0 does
> not. Is there a way to force dhcpcd _not_ to transmit this DUID thingy? If
> not, is there any chance of a noduid option in a future version?

You can remove duid from /etc/dhcpcd.conf
noduid would be counter intuitive.