Sending DHCP Option 10 with RouterOS DHCP Server

RouterOS General
1

Hi All,

I am trying to send DHCP Option 10 with the inbuilt RouterOS DHCP Server, however if I perform a packet capture, option 10 is not being included in the DHCP offer. However if I set the “code” to 12, its sent as expected.

Does anyone have any ideas?

My config looks like this:

 / ip dhcp-server option print
 # NAME                                                            CODE VALUE                                                           RAW-VALUE
 0 option10                                                          10 '95.177.139.87'                                                 5fb38b56

/ip dhcp-server network print detail
 0 ;;; Default Network
   address=10.0.130.0/24 gateway=10.0.130.1 dns-server=10.0.130.1 wins-server="" ntp-server=109.74.206.120 caps-manager="" boot-file-name="iprfp2G.tftp"
   dhcp-option=option10

Thanks!

2

The DHCP RFC says that the server may only send options which the client has asked for. So as a first step, take your capture and see the list of options supported by client in its DHCPDISCOVER and/or DHCPREQUEST - if Option 10 is not listed there, there is no way to force it to the DHCPOFFER etc.

3

Thanks, this helped point me in the right direction.

The Client requests Option 43 and expects Option 10 in the offer as a “sub” option of 43

So for my case it was:
Hex for Option 10: 0A
Hex for Len 4: 04
Hex for 95.177.139.87: 5fb18b57

Combined Hex: 0x0A045fb38b56

/ip dhcp-server option add name=option43 code=43 value=0x0A045fb38b56
4

Just double-check your hex - you’ve twice given the IP address with .87 as the last byte but in the final hex, you’ve put 0x56 instead of correct 0x57 both times.