[Dnsmasq-discuss] i need dhcp-match to find a match for an encapsulated value

[Geert Stappers]

On Tue, Jan 26, 2021 at 08:37:10PM +0100, Beta Tester wrote:
> hi,
> 
> i try to find the right syntax of dhcp-match to find a match for an
> dhcp option 175 with encapsualted option 235 with a specific value.
> 
> in wireshark the specific byte sequence of option 175 with the
> encapsulated option 235 looks like:
> 0xEB 0x03 0x01 0x15 0x01
> the 1'st byte is the encap option value (235 = ipxe.version),
> the 2'nd byte is the lengs of the encapsulated value (3 bytes),
> the 3'rd, 4'th and 5'th byte is the version value (major, minor, revision)
> 
> i need a match for the byte values 0x01 0x15 0x01
> 
> i tried several combinations like:
> dhcp-match=set:ipxe.version_1_21_1, 175, 235, 1b, 21b ,1b
> dhcp-match=set:ipxe.version_1_21_1, 175, 235, 1:21:1
> dhcp-match=set:ipxe.version_1_21_1, 175, 235, 01:15:01
> 
> with no luck...

Try
  dhcp-match=set:ipxe.vera, 175, 235, 1,21,1
  dhcp-match=set:ipxe.verc, 175, 235, 1,24,5

Elaborated
  short name
    vera for 1.21.1
    verc for 1.24.5
  all comma separated decimal values


> 
> or for an other option 175 with encapsulated option 16, the byte
> sequence looke like:
> 0x10 0x01 0x02
> 
> here i need a match for the value 0x02
> 
> but none of them seems to work.
> i did not find a example in the man page, nor in the example
> dnsmasq.conf file nor in the FAQ.
> 
> i am only able to get match for, if an encap option exists or if it
> doe not exist:
> 
> dhcp-match=set:ipxe.pxeext,           175, 16
> dhcp-match=set:ipxe.iscsi,            175, 17
> dhcp-match=set:ipxe.aoe,              175, 18
> dhcp-match=set:ipxe.http,             175, 19
> ...
> 
> 
> but i need a match for a specific value in the encapulated option.
> can somebody give me the right dhcp-match syntax for my needs?
> 
> thanks in advance.
 
It doesn't work that way.
Express your thankfullness upon getting a valuable response.



Regards
Geert Stappers
-- 
Silence is hard to parse