duid and dhcpd6.client-id

Glenn Satchell glenn.satchell at uniq.com.au
Mon Mar 31 10:01:40 UTC 2014

In the dhcp-options man page it is defined as

     option dhcp6.client-id string;

and in the dhcp-eval man page it defines what a string looks like


       A string, enclosed in quotes, may be specified as  a  data
       expression,  and  returns  the  text  between  the quotes,
       encoded in  ASCII.    The  backslash  ('\')  character  is
       treated  specially,  as  in C programming: '\t' means TAB,
       '\r' means carriage return, '\n' means newline,  and  '\b'
       means  bell.    Any  octal  value  can  be  specified with
       '\nnn', where nnn is any positive octal number  less  than
       0400.  Any hexadecimal value can be specified with '\xnn',
       where nn is any positive hexadecimal number less  than  or
       equal to 0xff.

     colon-separated hexadecimal list

       A list of hexadecimal octet values, separated  by  colons,
       may be specified as a data expression.

So you can specify a string in the two ways you have seen, text enclosed
in quotes, using \nnn as a way to represent octal caharcters that are not
printable ascii characters, eg null and so on. Alternatively pairs of
hexadecimal chars separated by colons, but with no quotes.

I believe the print function inside dhcpd will print strings with octal
escaps if it sees a few ascii characters in the string, otherwise it uses
the colon format.

For the config file either form can be used.


On Mon, March 31, 2014 6:47 pm, Andreas Burger wrote:
> hi there,
> i try to figure out how i have to write the dhcpd6.client-id
> in the dhcpd6.conf
> clientsystems are linux, macosx and windows7
> i tested mostly under linux.
> in the dhclient6.conf i tested with id in form xx:xx:xx....
> cleartext and \00\001\.... form
> in the dhcpd6.lease on the server i often end with ia-na entrys
> which heave sort of a prefix:
> \316o\334~\000\001....
> even if i do add literally the entry i see in the leasefile
> to the clientconfig the client does not get the address set in the
> serverconfig.
> my goal is to give fixed addresses, or at least, only give adresses to
> known hosts.
> is there any docuemntation about how theses ids are handled?
> regards
> andreas
> --
> ________________________________________________
> Andreas Burger
> Eidgenoessische Technische Hochschule Zuerich
> Departement Hest                          ISG
> LFV E31  8092 Zuerich        +41 44 632 68 54
> andreas.burger at hest.ethz.ch
> _________________________________________________
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