Persistent DUID for Client

rahul shukla shukla.rahulp at
Fri May 25 08:07:04 UTC 2012

I am using ISC DHCPV6 client (for my linux based board, kernel version
2.6.32) to get the IPV6 IP address. I have cross-compiled the ISC DHCPv6
code (version 4.2.3-P2) and get the 'dhclient' binary.

Issue1). Whenever I run this client, board gets a new IPv6 address. I
trapped the packets send by client and saw that every-time It sends a new
DUID. then I checked the client code and saw the LLT DUID is being
generated by LL address+current time which makes the new DUID everytime.

As per RFC 3315 "Clients and servers using this type of DUID MUST store the
DUID-LLT in stable storage, and MUST continue to use this DUID-LLT even if
the network interface used to generate the DUID-LLT is removed." So I
believe LLT DUID should be generated once and stored somewhere. That should
persists across the power cycles also. Pls. let me know if I understanding
is wrong.

Issue 2). If I specify a 'dhcp-client-identifier' in dhclient.conf, that ID
is also not taking effect. In what circumstances this ID will be used? I
checked the code and a variable 'path_dhclient_conf' which is holding the
path of config file received from command prompt is not being used. How can
I provide the client identifier ?

below is the command I am using to start dhclient:

'/usr/local/dhcp/sbin/dhclient -6 -d -cf /usr/local/dhcp/etc/dhclient.conf

Pls. help.

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