Ubuntu not responding my ARP request

[szhou42]

My os is running on top of QEMU, which runs on a ubuntu.

I have set up the tap device br0 so that my os and ubuntu are in the same network, sending and receiving raw packets between my os and the ubuntu is no problem.

However, the ubuntu never responds to my ARP packet, even though it certainly sees the ARP packets coming in (because i can see it in tcpdump)

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13:04:42.579969 ARP, Ethernet (len 6), IPv4 (len 4), Request who-has vagrant-ubuntu-trusty-32 tell 10.0.2.14, length 28
	0x0000:  0001 0800 0604 0001 5254 0012 3456 0a00  ........RT..4V..
	0x0010:  020e 0000 0000 0000 0a00 020f            ............

In case I've sent a malformed arp packet(which i m sure it's not since tcpdump can recognize it), i also tried sending arp from the ubuntu machine to itself.
Also no response.

The firewall is also disabled by

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sudo ufw disable

What could be the reason of this ?

[iansjack]

Try using wireshark and see what it makes of your packet.

[szhou42]

Try using wireshark and see what it makes of your packet.

Thanks for your advice !!

I compare my arp packet with one generated by arping and found that it's because I set the ethernet frame's destination mac address to 00:00:00:00:00:00 instead of FF:FF:FF:FF:FF:FF.