Linux NIC driver: what’s the UDP packet from 0.0.0.0 to 255.255.255.255?

I am playing with rhel6 and rhel 7 NIC driver.

The interesting thing is, when I do “ifup eth0” (eth0 is the NIC associated with my driver), I found Linux will try to send two special UDP packets, with source address of 0.0.0.0 and destination address of 255.255.255.255.

Can someone help me to understand what’s the purpose of those UDP packets?

Answer

This is a DHCP Discovery request. The interface is attempting to acquire an IP address from your DHCP server.