Bogus DHCP server in the network....

[TUDOR PANAITESCU <tpanaitescu () usa net>]

Hello fellow wizards,

Here's the picture. I am a client of Adelphia PowerLink CableTV. They use DHCP
for giving IP addresses. In the last weeks a bogus DHCP server showed up into
the network giving addresses in 192.168.244.128/25. The guy is using aliasing
on his Ethernet interface, he has an address aquired from the ISP in the ISP's
range and he configured his interface with 192.168.244.129 too. I have his
MAC. He gives DNS services. The system the hacker uses is totally protected,
no ports are "visible" to allow to try to do something to his system (can syn
flood be a solution?). Some time ago the hacker provided forwarding also but
now he's not forwarding anymore anoying lots of people in the net as they
don't have access to the INTERNET. I believe it is a UNIX box, most likely
LINUX with NAT. Now here comes the question: is anything there we can do to
block this guy ?

Any answer will be greately appreciated. I will sumarize also for archiving
purposes.

TIA & best regards,
Tudor

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