Je ne maitrise pas trop les options de tcpdump, tu aurais les pramètres ?
18:49:02.827620 02:a3:ec:3e:f0:00 (oui Unknown) > Broadcast, ethertype 802.1Q (0x8100), length 346: vlan 838, p 4, ethertype IPv4, 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 02:a3:ec:3e:f0:00 (oui Unknown), length 300
18:49:27.846667 02:a3:ec:3e:f0:00 (oui Unknown) > Broadcast, ethertype 802.1Q (0x8100), length 346: vlan 838, p 4, ethertype IPv4, 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 02:a3:ec:3e:f0:00 (oui Unknown), length 300
18:49:28.856496 02:a3:ec:3e:f0:00 (oui Unknown) > Broadcast, ethertype 802.1Q (0x8100), length 346: vlan 838, p 4, ethertype IPv4, 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 02:a3:ec:3e:f0:00 (oui Unknown), length 300
18:49:30.863792 02:a3:ec:3e:f0:00 (oui Unknown) > Broadcast, ethertype 802.1Q (0x8100), length 346: vlan 838, p 4, ethertype IPv4, 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 02:a3:ec:3e:f0:00 (oui Unknown), length 300
18:49:35.865854 02:a3:ec:3e:f0:00 (oui Unknown) > Broadcast, ethertype 802.1Q (0x8100), length 346: vlan 838, p 4, ethertype IPv4, 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 02:a3:ec:3e:f0:00 (oui Unknown), length 300
18:49:42.874596 02:a3:ec:3e:f0:00 (oui Unknown) > Broadcast, ethertype 802.1Q (0x8100), length 346: vlan 838, p 4, ethertype IPv4, 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 02:a3:ec:3e:f0:00 (oui Unknown), length 300
^C