[Kea-users] Newbie questions

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[Kea-users] Newbie questions

Tom Gillman
Hi guys, new user here and relatively new to the world of DHCP. I've been playing around with kea a bit to see if it will work in a project I'm doing, and I'm noticing some odd behavior. I'm hoping it's due to my inexperience, but I would welcome any feedback.


I'm attempting to have option 43 data populated, and I'm doing the following test:


$ sudo ./dhtest -m "12:34:56:78:90:12" -o "iDRAC" -i enp0s8 -V -S 192.168.33.44

DHCP discover sent       - Client MAC : 12:34:56:78:90:12
DHCP offer received      - Offered IP : 192.168.33.101

DHCP offer details
----------------------------------------------------------
DHCP offered IP from server - 192.168.33.101
Next server IP(Probably TFTP server) - 0.0.0.0
Subnet mask - 255.255.255.0
Router/gateway - 192.168.33.1
DNS server - 192.168.33.1
DNS server - 192.168.33.2
Option no - 15, option length - 11
  OPTION data (HEX)
    76 69 63 65 72 6F 79 2E 63 6F 6D
  OPTION data (ASCII)
    viceroy.com
Lease time - 0 Days 1 Hours 0 Minutes
Option no - 53, option length - 1
  OPTION data (HEX)
    02
  OPTION data (ASCII)
  
DHCP server  - 192.168.33.44
Option no - 58, option length - 4
  OPTION data (HEX)
    00 00 03 84
  OPTION data (ASCII)
    #
Option no - 59, option length - 4
  OPTION data (HEX)
    00 00 07 08
  OPTION data (ASCII)
  
----------------------------------------------------------

DHCP request sent        - Client MAC : 12:34:56:78:90:12
DHCP ack received        - Acquired IP: 192.168.33.101

DHCP ack details
----------------------------------------------------------
DHCP offered IP from server - 192.168.33.101
Next server IP(Probably TFTP server) - 0.0.0.0
Subnet mask - 255.255.255.0
Router/gateway - 192.168.33.1
DNS server - 192.168.33.1
DNS server - 192.168.33.2
Option no - 15, option length - 11
  OPTION data (HEX)
    76 69 63 65 72 6F 79 2E 63 6F 6D
  OPTION data (ASCII)
    viceroy.com
Lease time - 0 Days 1 Hours 0 Minutes
Option no - 53, option length - 1
  OPTION data (HEX)
    05
  OPTION data (ASCII)
  
DHCP server  - 192.168.33.44
Option no - 58, option length - 4
  OPTION data (HEX)
    00 00 03 84
  OPTION data (ASCII)
    #
Option no - 59, option length - 4
  OPTION data (HEX)
    00 00 07 08
  OPTION data (ASCII)
  
----------------------------------------------------------





Based on my (attached) config, I would expect that the code 43 data would be populated, the log (attached) shows that I get the class selection correctly. However, I do not. I'm also slightly confused by what DOES get returned, as according to the config definitions, I should see:

domain-search (code 119)
boot-file-name (code 67)
default-ip-ttl (code 23)

returned also, and I don't see them populated either. I'm also slightly confused as to why I'm seeing code 53, code 58, and code 59 populated, as I don't see any definition for them and don't see anything in the config that they might map to.

Lastly, in the Kea Administrators Guide, table 8.1 indicates that most data is not returned unless requested, and the wording on that is slightly confusing. Does that mean if the client does not specifically request those codes, they will not be returned? Or does it mean that if they're defined, they will be returned to client when it requests a lease? Either way there appears to be a disconnect, because data expected to be returned is not, and data not requested (and indicated as not being returned in the table) is in fact being returned.

As I said before, I'm somewhat new to this, so please bear with me. If there are informational resources anyone can direct me to that might point me in the right direction, please let me know.

Thanks,

 -Tom G

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dhcp4.conf (13K) Download Attachment
dhcp4.log (13K) Download Attachment
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Re: [Kea-users] Newbie questions

Francis Dupont
You need either a PRL option (code 55) to list requested options in
the discover or request, or to set always-send to true in option data
entries of a recent enough Kea config.

Regards

Francis Dupont <[hidden email]>

PS: always-send adds the option code to the PRL option which is BTW
the way to do the same thing in ISC DHCP. For DHCPv6 you have the same
thing with the ORO option. Only a few "system" options are added even
when not requested, cf DHCP protocol specs.
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