We have an ALFA AWUS036ACM. We need to work in monitor mode for investigation purposes. Although injection is possible, we have seen some troubles concerning with the following characteristics:
The number of retransmissions (retry limit short and long).
rts activation (rts threshold).
rate used in retransmissions (by default multi-rate retry chain seems to be used although in other ALFA cards like AWUS036ACH retransmissions use the same rate as the original data). We need control and/or deactivate the MRR process.
Specifically, we have seen that:
If we inject 802.11a or 802.11n frames, the number of retransmissions is always 15 (plus the original data), no matter the configured values of the retry limit short and the retry limit long.
Both when we inject 802.11a or 802.11n frames, for each retransmission, the rate falls back (for example, if 802.11n is used and the selected transmission rate is MCS 4, retransmissions are done with MCS3, MCS2, MCS1, MCS0 and then, 11 times with 6Mbps).
When we inject 802.11ac frames, the number of retransmissions depends on the selected rate. Starting from the selected rate (for example, MCS4), retransmissions fall back to MCS0 (MCS3 to MCS0) and then, only 1 retransmission with 6Mbps occurs.
When we inject 802.11n, rts-cts transmission is always present (even though, rts threshold is off or rts threshold is set to a high value (2000)). However, this does not occur when 802.11a or 802.11ac injection is select.
In the file attached, we include information about the context, tests and detected problem.
Hi!
We have an ALFA AWUS036ACM. We need to work in monitor mode for investigation purposes. Although injection is possible, we have seen some troubles concerning with the following characteristics:
The number of retransmissions (retry limit short and long).
rts activation (rts threshold).
rate used in retransmissions (by default multi-rate retry chain seems to be used although in other ALFA cards like AWUS036ACH retransmissions use the same rate as the original data). We need control and/or deactivate the MRR process.
Specifically, we have seen that:
If we inject 802.11a or 802.11n frames, the number of retransmissions is always 15 (plus the original data), no matter the configured values of the retry limit short and the retry limit long.
Both when we inject 802.11a or 802.11n frames, for each retransmission, the rate falls back (for example, if 802.11n is used and the selected transmission rate is MCS 4, retransmissions are done with MCS3, MCS2, MCS1, MCS0 and then, 11 times with 6Mbps).
When we inject 802.11ac frames, the number of retransmissions depends on the selected rate. Starting from the selected rate (for example, MCS4), retransmissions fall back to MCS0 (MCS3 to MCS0) and then, only 1 retransmission with 6Mbps occurs.
When we inject 802.11n, rts-cts transmission is always present (even though, rts threshold is off or rts threshold is set to a high value (2000)). However, this does not occur when 802.11a or 802.11ac injection is select.
In the file attached, we include information about the context, tests and detected problem.
tarjeta ac_attach.pdf
We would be very grateful if you could provide us some indication in order to resolve the issue or alternatively someone to contact.
Many thanks in advance,
Best regards,
Ángela Hernández