Usage
-----
dhcp_user_xdp takes network interface and dhcp relay server IP
as inputs and stores it in a map. Filters the incoming DHCP requests and inserts
option 82 in the DHCP request packets and overwrites the destination IP to that
of DHCP relay server IP.

Build instructions:
cd bpf-examples/dhcp-relay
make

Loading bpf program:
sudo ./dhcp_user_xdp -i <netif> -d <dhcp relay IP>
where,
netif: Ingress network interface name

unloading program:
sudo ./dhcp_user_xdp -i <netif> -u 

To run in SKB mode:
add option "-m skb" for both load and uload commands

Verify using tcpdump:
sudo tcpdump -s 0 -i <netif> port 67 and port 68 -vvv