Problem about dhcp option 125

David Ganor david at
Mon Mar 19 11:55:18 UTC 2012

Hi L'oiseau

Please find below an example of defining option#125 with 2 suboptions:
suboption#1 with length=1 and suboption#2 with length=4, both for a
CableLabs vendor (ID=4491)
This is the way I'm using it in the dhclient.conf, but I think it could be
used in dhcpd.conf as well:

option vendor-identifying-vendor-specific code 125 = { integer 32, integer
8, integer 8, integer 8, integer 8, integer 8, integer 8, ip-address };
send vendor-identifying-vendor-specific 4491 9 1 1 0 2 4;

David Ganor

-----Original Message-----
From: at
[ at] On
Behalf Of L'oiseau de mer
Sent: Monday, March 19, 2012 9:26 AM
To: dhcp-users at
Subject: Problem about dhcp option 125

Recently i need set a dhcp sever with option 125, i use the verion 4.2.3-P2
but i don't know how to configure.

I also see this men page about vendor identify, it says that use option
vivso, and later follow a string.

So i try to these tests:
send vivso "openbsd 5";
send vivso 6F:70:65:6E:62:73:64:20:35;
option vivso 6F:70:65:6E:62:73:64:20:35; option space openbsd code width 2
length width 2; option openbsd.test1-location code 1 = text; option
openbsd.test2-probability code 2 = integer 8; option vsio.openbsd code 12345
= encapsulate openbsd;

option space BSD;
option BSD.option-125 code 125 = string; option BSD.option-125 "openbsd";

But these tests is all invalid. When i see these packets in wireshark, i
always findn't this string "openbsd".

I don't know where is this problem, anyone can't help me?
Thanks very much.
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