duplicate mac addresses requesting dhcp server

Gilbert Coles gilbertx07 at hotmail.com
Wed Oct 18 07:39:06 UTC 2006


I've got a query regarding duplicate MAC addresses requesting an IP address 
from dhcpd.

Consider a scenario where pc1 has mac1 and asks the dhcp server for a lease 
for ip1. The dhcp
server is dynamically allocating IPs from a pool and so it assigns the lease 
for ip1. If another pc2
comes along with its MAC address spoofed to mac1 and asks the dhcp server 
for an ip (not
necessarily ip1) will the server assign a lease to pc2?

Now if the dhcp server is configured to reserve a fixed-address ip1 to mac1 
and pc1 comes along
and is given its ip, will pc2, with its mac spoofed to mac1 be given the 
fixed-address ip1?

So my question is: does the dhcp server contain logic to check the leases 
file entry assigned to
mac1 before actually serving another request coming from apparently the same 


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