[Kea-users] kea answers to relay using giaddr instead of source address. any way to fix?

[Sergey Klusov]

On Чт 28.09.2017 14:37, Francis Dupont wrote:
> IMHO the simplest is to write a little hook which resets the giaddr,
> or to understand why the client or relay sets it and fix this.
>
> Regards
>
> Francis Dupont <fdupont at isc.org>
>
Client is a mikrotik router with some specific setup: lan segment which 
it runs relay for is in VRF instance, but there is a limitation in 
RouterOS that dhcp-relay destination will be contacted using main 
routing table.

Because of that, relay messages are sent out-of-band, using different 
interface.

Right now i'm working on supplying additional option 82 information to 
kea, by wich it should select appropriate subnet.

14:30:40.033857 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto 
UDP (17), length 360)
     x.x.x.156.67 > x.x.x.90.67: [udp sum ok] BOOTP/DHCP, Request from 
f4:8b:32:a3:79:3f, length 332, hops 1, xid 0xa111bece, secs 17, Flags 
[none] (0x0000)
           Gateway-IP x.x.x.156
           Client-Ethernet-Address f4:8b:32:a3:79:3f
           Vendor-rfc1048 Extensions
             Magic Cookie 0x63825363
             DHCP-Message Option 53, length 1: Discover
             Client-ID Option 61, length 7: ether f4:8b:32:a3:79:3f
             MSZ Option 57, length 2: 1500
             Vendor-Class Option 60, length 18: "android-dhcp-6.0.1"
             Hostname Option 12, length 17: "MINOTELTE-MiPhone"
             Parameter-Request Option 55, length 9:
               Subnet-Mask, Default-Gateway, Domain-Name-Server, Domain-Name
               MTU, BR, Lease-Time, RN
               RB
             Agent-Information Option 82, length 23:
               Circuit-ID SubOption 1, length 6: M-~^K.M-AM-tz
               Remote-ID SubOption 2, length 13: 100.101.101.0

Can someone tell me how to make kea select subnet 100.101.101.0/24 by 
Remote-ID "100.101.101.0" suboption and giaddr?

Should i define some class and apply it to subnet?