DHCP reply with opt82

Alex admin at u-tele.com
Mon Jul 19 23:12:58 CEST 2010


FreeRADIUS Version 2.1.10 (from git sources).
I'm using dhcp feature of freeradius to assign static ips to computers

Sometimes its needed to reply to dhcp packets with same opt82 as in
request. For example, cisco uses opt82 from replied packet to know from
which port request has arrived (IP source guard, "ip verify source
port-security" interface command).

For this scenario, I added following to dhcp update sections:
DHCP-Agent-Circuit-Id := "%{request:DHCP-Agent-Circuit-Id}"
DHCP-Agent-Remote-Id := "%{request:DHCP-Agent-Remote-Id}"

In this case, radius debug output shows correct assignment of options:
Sending DHCP-Offer of id 7c0f40cd from to x.x.x.1:67
        DHCP-Subnet-Mask =
        DHCP-Router-Address = x.x.x.1
        DHCP-Domain-Name-Server = y.y.y.y
        DHCP-IP-Address-Lease-Time = 86400
        DHCP-DHCP-Server-Identifier = z.z.z.z
        DHCP-Agent-Circuit-Id = 0x000401e30420
        DHCP-Agent-Remote-Id = 0x000600FFFFFFFF00
Finished request 10.

but both this two values (0x000401e30420 and 0x000600FFFFFFFF00) are
assigned to DHCP-Relay-Agent-Information.
tcpdump shows both as opt82 suboption 0:

Need help in setting this options correctly.

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