Linux DHCP sending wrong parameters in offer packet

[Gaikwad Yogesh]

Hi,

There is issue that linux DHCP is sending wrong parameters while sending offer packet for Cisco AP's in one of our office locations.

I have taken packet captures on the DHCP server side.

As you can see in below packet capture there is DHCP DISCOVER message from Cisco AP requesting for IP and other parameters.

Then in DHCP offer packet, it offers IP from correct subnet, but with wrong router IP, subnet mask and broadcast address.

Basically, my observation is that it is giving wrong parameters in offer from the topmost subnet (as linux works from top to bottom approach) that has cisco option 43 configured. If I remove the Cisco option 43 from that subnet then it provides parameters from next subnet which has the Cisco option 43 in it.

The correct subnet from which I am expecting that the AP should get all its parameters is configured at the end of the DHCP conf file.


DHCP DISCOVER PACKET

[cid:image001.png at 01D4B4D9.6F320900]


DHCP OFFER PACKET

[cid:image002.png at 01D4B4D9.6F320900]




Best regards,

Yogesh Gaikwad, Technical Architect - TECA Network

Tieto Corporation, TSM

email Yogesh.Gaikwad at tieto.com<mailto:Yogesh.Gaikwad at tieto.com>, direct +91 (0)2067303120
Wing 1, Cluster D, EON Free Zone, MIDC Kharadi Knowledge Park, Pune - 411 014, India

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