DHCP Client Identifier/UID field issue
jeff_bair at rescomp.berkeley.edu
Mon Aug 16 22:29:50 UTC 2010
I'm currently trying to debug a problem with how our dhcp server populates our dhcpd.leases file and have noticed an interesting issue. When I populate the dhcp client identifier/uid field with
a string (more specifically a string that contains an id and a private IP address that is separated by two periods such as '38344..10.0.0.5') I have issues when I release the lease and try to
reacquire another lease using the same hardware address and uid. According to the dhcp rfc I SHOULD get the same lease back which is what happens when I tried acquiring, releasing, and reacquiring a
lease without the uid field populated. However, once I introduce the uid field, even though it's the same uid as before, I receive a different IP address for the lease. Is there a specific reason
for this behavior?
What I am currently trying is doing an omapi lookup on the leases file for the hardware address and seeing if there was a previous lease with that hardware-address and seeing if it is free to take
and simply send a DHCP Request packet for that specific IP address. This is not as ideal as I have to do an OMAPI lookup each time a user tries to get a lease but the larger problem is that upon the
second time a user logs in I am unable to do lookups by hardware-address as it says "can't open object: more than one object matches key". Only one IP address has been put in use so I'm not exactly
sure why this is occurring since when I do a lookup by uid or IP address it works perfectly fine.
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