Supported format for Client Identifier.

David W. Hankins dhankins at
Wed Jun 17 17:45:08 UTC 2009

On Wed, Jun 17, 2009 at 09:36:33PM +0800, T MANIKANDAN-PKXR74 wrote:
> how to set the IAID & DUID field in ISC DHCP CLIENT?

dhclient doesn't send a client-identifier by default, and we haven't
sat down to think about the migration path for transmitting DUID based
DHCPv4 client identifiers (yet).  I suspect we will reapproach this
issue when we integrate the DHCPv6 and DHCPv4 clients into one client.

That said, you can always send whatever client-identifier you want by
simply configuring it in dhclient.conf;

  send dhcp-client-identifier [string] ;

The '[string]' config syntax is either a colon-separated-hexadecimal
string (a colon between each octet), which could configure an RFC 4361
client identifier in this manner:


(Where an IAID of 1 is included here, and the DUID trails the end.)

Or it is simply a quoted literal with octal escapes;

  "\000For neither man nor angel can discern Hypocrisy, the only evil that walks Invisible, except to God alone, By his permissive will, through heaven and earth.";

("\000" is provide for example only, there is truly no real reason to
include it unless you think it likely there may exist a system whose
HTYPE is 'F' and whose MAC ADDRESS may be the remainder of the string,
and may also run Windows, thus presenting a potential collision).

The quoted literal tends to be used for client-identifiers that are
text based.  It does not necessarily need to be a quotation.

David W. Hankins	"If you don't do it right the first time,
Software Engineer		     you'll just have to do it again."
Internet Systems Consortium, Inc.		-- Jack T. Hankins
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