dhcp investigation

["mikhail malamud" <mikhail.malamud@drexel.edu>]

Hello -
I am running obsd 2.8. My isp, which provides network access for the
entire apartment building (on the same subnet) cut me a deal. I gave
them my mac address and they resolve me to the same ip address.
Everything was well up until today, someone possibly decided to run
their own dhcp server. I guess due to the nature of DHCP protocol,
dhclient picks up an ip from the first dhcp server it finds. I assume
that whoever runs "auxiliary" dhcp server is giving out 0.0.0.0 address
to all its clients because once in a while I get the following message
pop up on the console:

"/ bsd: Duplicate IP address 0.0.0.0 sent from ethernet address
blah:blah:blah" (not mine)

And when I try to start dhclient, I get the following error:

..."Listening on BPF/xl0/mymacaddress/unattached
Sending on BPF/xl0/mymacaddress/unattached
myhostname dhclient: Cant bind to dhcp address: Address already in use."

Unfortunately, I am only one of few people who is using dhcp as opposed
to PPPoE. ISP could not resolve the problem even though they double
checked their dhcp server and I gave them the mac address that popped up
one the console. My questions are. Is someone else really running
another dhcp server or am I completely off the track or there is simply
not enough information to make any decisions. How can I find out more
information about the dhcp server given the mac address and obsd network
tools so I can give it to the ISP. Perhaps someone had to deal with the
same situation.

Thank You.