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Re: [MiNT] OT: Re: Weird ping reply



Hi,

I seem to understand it all now. The network scheme is that there is a NAT DHCP capable HUB to which all the machines are connecting to. And to be able to get DHCP address from that box ARAnyM uses TAP tunnel that is bridged on the Windows machine (to enable UDP broadcast go to the DHCP box - have it on the same network branch). The ussuall way the packets are travelling is that they go to the HUB and then back to the other machine. This is perfectly ok for the ARAnyM machine to put there the HUB MAC address. But the Windows bridge implementation realizes that the host IP corresponds to the machine it is running on and therefore it doesn't pass the packet out to the HUB box. It does not however replace the MAC inside of such a packet which is the thing it causes ping not to work correctly.

Sorry for the offtopic here, but it was at least related to mintnet and ARAnyM ;)

regards

STanda


Standa Opichal wrote:
Hi,

Well, I understand how the HW address is assigned, but the point is that the ping doesn't work from the user point of view (Timeout) although the packets are actually sent and received on the NIF. That's why I am suspicious about the HW address. Also the HW address should be changed by the router to the destination one coresponding to the IP of the machine. Still don't understand what I am missing here.

STanda


Adam Klobukowski wrote:

Standa Opichal napisał(a):

Hi,

OK, I found out that the HW address I am getting is my HUB's one. It seems that the bridge or the NAT in the HUB exchanged this. I don't know exactly why, but it is definitely not a mintnet fault.

Anyway, does anyone have idea what was it going there?



If I understand it correctly, addreses you shown are MAC adressed of the network cards (and aport in the hub). They are used by Ethernet protocols.

Ping howewer works on the higher level. It works on the IP protocol level.

When you ping or hust tty to connect something using IP protocol), your computer first uses ARP (Address resolution protocol) to question the network where to send packets. Why? Becouse IP addres may be world-wide, and MAC is locally. IP packets gets encapsulated into Ethernet packets, and then sent into network. But where? This is where ARP comes handy. ARP allows you to ask: "What is a MAC addres of the device that I sgould sent IP packets with the following IP address (ie. gateway)".

Maybe it is a bit complicated, and my english is not good enough, but basically this is how it works.