iptables vs. isc-dhcp-server?

Question

linux

Good afternoon, hackers!
There is an old server on Debian squeeze amd64. It is running isc-dhcp-server.
Clients successfully successfully receive ip addresses and everything is OK
To manage the iptables settings in the system, vuurmuur is used. For research purposes, all incoming was denied to the server, but despite this, client requests continue to bypass the iptables rules and receive addresses.
I post a list of applied rules
. I ask for advice from experienced colleagues - how can this be?
Thanks in advance

Answer 1

dhcp works through raw sockets, and they work "bypassing" iptables.

Answer 2

you can block like this
iptables -t raw -A PREROUTING -p udp --dport 68 -j DROP
iptables -t raw -A PREROUTING -p udp --dport 67 -j DROP

Answer 3

Try loading some LiveCD and see if it gets an IP the first time?