Option to refill MAC address on Bridged WIFI

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DenisF
Posts: 40
Joined: 16. May 2012, 15:00

Option to refill MAC address on Bridged WIFI

Post by DenisF »

Hello,
I'm using some industrial software that use Ethernet connection ( Profinet DCP).
This protocol only use MAC address, no TCP/IP.
When software (TIA-Portal) ask for accessible device, it send an Ident request to 01:0E:CF:00:00:00.
All other PN device answer with their identities. (Ident Ok)
The mistake is that when we use Bridged connection over WIFI, all streams are sent with host WIFI MAC address so device respond to that interface.
And guest don't take care of them as they are addressed to wrong interface...
So, is it possible to add an option (like Promiscuous Mode) that refill all received packets with guest MAC address?

For information, here the packet take by WireShark on guest:

Code: Select all

Frame 151: 60 bytes on wire (480 bits), 60 bytes captured (480 bits) on interface 0
Ethernet II, Src: PcsCompu_58:48:5d (08:00:27:58:48:5d), Dst: PN-MC_00:00:00 (01:0e:cf:00:00:00)
PROFINET acyclic Real-Time, ID:0xfefe, Len:  44
PROFINET DCP, Ident Req, Xid:0xd01000e, All
0000   01 0e cf 00 00 00 08 00 27 58 48 5d 88 92 fe fe   ..Ï.....'XH]..þþ
0010   05 00 0d 01 00 0e 00 80 00 04 ff ff 00 00 00 00   ..........ÿÿ....
0020   00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
0030   00 00 00 00 00 00 00 00 00 00 00 00               ............
And the same packet on host:

Code: Select all

Frame 140: 60 bytes on wire (480 bits), 60 bytes captured (480 bits) on interface 0
Ethernet II, Src: Universa_5b:fa:50 (44:39:c4:5b:fa:50), Dst: PN-MC_00:00:00 (01:0e:cf:00:00:00)
PROFINET acyclic Real-Time, ID:0xfefe, Len:  44
PROFINET DCP, Ident Req, Xid:0xd01000e, All
0000   01 0e cf 00 00 00 44 39 c4 5b fa 50 88 92 fe fe   ..Ï...D9Ä[úP..þþ
0010   05 00 0d 01 00 0e 00 80 00 04 ff ff 00 00 00 00   ..........ÿÿ....
0020   00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
0030   00 00 00 00 00 00 00 00 00 00 00 00               ............
Now a device response:

Code: Select all

Frame 147: 106 bytes on wire (848 bits), 106 bytes captured (848 bits) on interface 0
Ethernet II, Src: Siemens_1b:11:3d (ac:64:17:1b:11:3d), Dst: Universa_5b:fa:50 (44:39:c4:5b:fa:50)
PROFINET acyclic Real-Time, ID:0xfeff, Len:  90
PROFINET DCP, Ident Ok , Xid:0xd01000e, Dev-Options(1), DeviceVendorValue, NameOfStation:"af1", Dev-ID, Dev-Role, Dev-Instance, IP
0000   44 39 c4 5b fa 50 ac 64 17 1b 11 3d 88 92 fe ff   D9Ä[úP¬d...=..þÿ
0010   05 01 0d 01 00 0e 00 00 00 50 02 05 00 04 00 00   .........P......
0020   02 07 02 01 00 0d 00 00 53 49 4d 41 54 49 43 2d   ........SIMATIC-
0030   48 4d 49 00 02 02 00 05 00 00 61 66 31 00 02 03   HMI.......af1...
0040   00 06 00 00 00 2a 04 0d 02 04 00 04 00 00 00 00   .....*..........
0050   02 07 00 04 00 00 00 00 01 02 00 0e 00 01 ac 19   ..............¬.
0060   d5 03 ff ff ff 00 00 00 00 00                     Õ.ÿÿÿ.....
Thanks
DenisF
Posts: 40
Joined: 16. May 2012, 15:00

Re: Option to refill MAC address on Bridged WIFI

Post by DenisF »

Up.
We need it...
andyp73
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Re: Option to refill MAC address on Bridged WIFI

Post by andyp73 »

DenisF wrote:The mistake is that when we use Bridged connection over WIFI, all streams are sent with host WIFI MAC address so device respond to that interface.
To quote Socratis: Bridged networking is outside the WLAN specification. Bridging to wireless is not really bridging. The guest shares the MAC of the host and the host does a sort of MAC-NAT translation based on IP addresses.

If you are trying to run a protocol that doesn't use TCP/IP and therefore doesn't include an IP address then you won't be able to get bridged to Wi-Fi to work in your use case.

-Andy.
My crystal ball is currently broken. If you want assistance you are going to have to give me all of the necessary information.
Please don't ask me to do your homework for you, I have more than enough of my own things to do.
DenisF
Posts: 40
Joined: 16. May 2012, 15:00

Re: Option to refill MAC address on Bridged WIFI

Post by DenisF »

Hello,

@andyp73: I don't see what is so difficult to add this option.
Host can replace the first bytes if they are identic to Host Bridged MacAddress. Not depending of Protocol.
Sure, it's not secure but it's an option like Promiscuous Mode is. And will be disabled by default.
DenisF
Posts: 40
Joined: 16. May 2012, 15:00

Re: Option to refill MAC address on Bridged WIFI

Post by DenisF »

Hello,
Any news on it?
scottgus1
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Re: Option to refill MAC address on Bridged WIFI

Post by scottgus1 »

Not that I've heard of. Enhancement requests can be posted on the Bugtracker. However, be prepared for not having it implemented due to inability to get beyond "it can't be done", unless you hunt through the source code and the Wi-Fi specification and figure it out yourself. User code is considered for inclusion.
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