Monday, January 26, 2009

Improvements to airbase-ng

Support was added for three new command line parameters:

-P : respond to all probes, even when specifying ESSIDs
-I interval : sets the beacon interval value in ms
-C seconds : enables beaconing of probed ESSID values
When using a list of ESSIDs, all ESSIDs will be broadcast with beacons. As extra ESSIDs are added, the beacon interval value is now adjusted based on the number of ESSIDs times the interval value (0x64 is default still). To support "fast" beaconing of a long list of ESSIDs, the -I parameter can be used to set a smaller interval. To get 0x64 interval for N beacons, set the -I parameter to 0x64/N. If this value goes below ~10 or so, the maximum injection rate will be reached and airbase-ng will not be able to reliable handle new clients. Since each card's injection rates are different, the -I parameters allows it to be tuned to a specific setup and injection speed based on the number of beacons.

When using one or more ESSIDs, the -P parameter causes airbase to reply to ALL probe requests. Without -P, the old behavior of ignoring probes for non-matching ESSIDs will be used.

When running in the default mode (no ESSIDs) or with the -P parameter, the -C option can be used to enable beacon broadcasting of the ESSIDs seen by the directed probes. This allows one client which is probing for a network to result in a beacon for the same network for a brief period of time (the -C parameter, which is the number of seconds to broadcast new probe requests). This works well when some clients are sending directed probes, while others listen passively for beacons. A client which does directed probes results in a beacon which wakes up the passive client and causes the passive client to joint he network as well. This is especially useful with Vista clients (which listens passively for beacons in many cases) which share the same WiFi? network as Linux/Mac OS X clients which send directed probes.

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