Hello, I need to trace between two WiFi devices, connected to the same A.P. I do't need to trace at radio level, but I just need (want!) to see from Ethernet level, so I guess I simply need a WiFi card/adapter/dongle able to accept "promiscuous" mode.
Yes, I red carefully (I hope) "WLAN (IEEE 802.11) capture setup" paragrph, but I am confused: I don't need to capture radio-level, I don't need to capture all SSID's but I need to see packets not directed to me. Can you confirm promiscuous mode is NOT what I need?
I tried: Intel Link 5100 AGN Linksys Wireless-G Qualcomm Atheros AR928X
With all of them, I don't see all packets and it looks they fail to enter promiscuous mode: once I see the very first ARP-RQ, I don't see anything else between the two devices. I see some other random messages from other devices.
Curiously, with ifconfig wlp3s0, I see the board is NOT in promiscuous mode once Wireshark is started. I close Wireshark, i force the board in promiscuous mode, I restart Wireshark but I still see only broadcast.
Any suggestions for USB WiFi dongles with divers implementing promiscuous mode (Linux)?
asked 24 Mar '17, 03:24
I think you will need monitor AND promiscuous mode on the wifi adapter. Promiscuous mode is great if the actual ethernet frames you are looking for (i.e. from the other devices under review) are available at the network interface - they would be passed up for analysis. However, just like in a wired switch environment, if they are not at the interface promiscuous mode won't help.
Imagine the WiFi adapter will filter out unicast frames not destined for your host, much as an ethernet bridge/switch will do. You might find some exceptions, but all of the adapters I have used have this filter on by default. To remove this filter, you want to put the adapter in monitor mode. I realize you don't want everything, but with a wifi adapter in monitor + promiscuous mode, I think you will get everything and then it becomes a filter exercise to isolate what you want. Luckily, Wireshark does a fantastic job with display filters.
Another option is two APs with a wired link in between. Have a wireless client on one AP, and a wireless client on the second AP. You could sniff the wire connecting the APs with a mirror port/tap/whatever, and get the data between the devices that way. This has the option of not needing to decrypt traffic, assuming you are using WPA2 on your wireless links. The downside is having to configure/manage two APs.
answered 24 Mar '17, 03:36