u8.4 Wireless Networks

u8.4 Wireless Networks

1. Access point roaming

   • Each AP is configured to use a different 1 of the 14 channels to allow AP's to overlap
     • the 14 channels all overlap with the channels either side,
       • Only three of the channels are completely non-overlapping.
         • these 3 non-overlapping channels that should be used to provide coverage over multiple cells.
   • As station moves between AP's it can associate to the AP with the strongest signal
   • AP might force a station to disassociate form it by sending disassociaite messages when NW traffic is too high
     • This allows a crude form of load balancing to take place

2. Interception

   • Standard wireless NICs use an omni-directional antenna. This receives & transmits in a 360-degree arc.
     • A directional antenna receives & transmits in a much smaller arc (10 - 15 degrees if pointed in the direction of a signal source can receive weaker signals than an omni-directional antenna
       • Using a directional antenna can further increase the range that an 802.11 signal can be received from.
   • War driving
     • Simply using a Station and some software, roam around and collect AP information
       • WD software records AP, MAC address, network name, Signal strength, noise level
         • If used with GPRS can record geo location
       • Return at any time and try to expoloit the AP
       • Examples of WD Software = Netstumbler, THC-Wardrive, FreeStumble