How do I limit configure WPA supplicant to scan for 11g channels only?

Question

In order to reduce the scanning time, I'd like to limit the scanning to 11g only

My current list of channels

# ifconfig wlan0 list regdomain
:regdomain 0 country US anywhere -ecm
Channel   1 : 2412  MHz 11b          Channel  60 : 5300  MHz 11a          
Channel   1 : 2412  MHz 11g          Channel  62 : 5310  MHz 11a          
Channel   2 : 2417  MHz 11b          Channel  64 : 5320  MHz 11a          
Channel   2 : 2417  MHz 11g          Channel 100 : 5500  MHz 11a          
Channel   3 : 2422  MHz 11b          Channel 102 : 5510  MHz 11a          
Channel   3 : 2422  MHz 11g          Channel 104 : 5520  MHz 11a          
Channel   4 : 2427  MHz 11b          Channel 108 : 5540  MHz 11a          
Channel   4 : 2427  MHz 11g          Channel 110 : 5550  MHz 11a          
Channel   5 : 2432  MHz 11b          Channel 112 : 5560  MHz 11a          
Channel   5 : 2432  MHz 11g          Channel 116 : 5580  MHz 11a          
Channel   6 : 2437  MHz 11b          Channel 118 : 5590  MHz 11a          
Channel   6 : 2437  MHz 11g          Channel 120 : 5600  MHz 11a          
Channel   7 : 2442  MHz 11b          Channel 124 : 5620  MHz 11a          
Channel   7 : 2442  MHz 11g          Channel 126 : 5630  MHz 11a          
Channel   8 : 2447  MHz 11b          Channel 128 : 5640  MHz 11a          
Channel   8 : 2447  MHz 11g          Channel 132 : 5660  MHz 11a          
Channel   9 : 2452  MHz 11b          Channel 134 : 5670  MHz 11a          
Channel   9 : 2452  MHz 11g          Channel 136 : 5680  MHz 11a          
Channel  10 : 2457  MHz 11b          Channel 140 : 5700  MHz 11a          
Channel  10 : 2457  MHz 11g          Channel 149 : 5745  MHz 11a          
Channel  11 : 2462  MHz 11b          Channel 151 : 5755  MHz 11a          
Channel  11 : 2462  MHz 11g          Channel 153 : 5765  MHz 11a          
Channel  36 : 5180  MHz 11a          Channel 157 : 5785  MHz 11a          
Channel  38 : 5190  MHz 11a          Channel 159 : 5795  MHz 11a          
Channel  40 : 5200  MHz 11a          Channel 161 : 5805  MHz 11a          
Channel  44 : 5220  MHz 11a          Channel 165 : 5825  MHz 11a          
Channel  46 : 5230  MHz 11a          Channel 167 : 5835  MHz 11a          
Channel  48 : 5240  MHz 11a          Channel 169 : 5845  MHz 11a          
Channel  52 : 5260  MHz 11a          Channel 171 : 5855  MHz 11a          
Channel  54 : 5270  MHz 11a          Channel 173 : 5865  MHz 11a          
Channel  56 : 5280  MHz 11a  

How can I do that on FreeBSD?

Answer 1

Use the chanlist option with ifconfig;

 chanlist channels
         Set the desired channels to use when scanning for access points,
         neighbors in an IBSS network, or looking for unoccupied channels
         when operating as an access point.  The set of channels is speci‐
         fied as a comma-separated list with each element in the list rep‐
         resenting either a single channel number or a range of the form
         “a-b”.  Channel numbers must be in the range 1 to 255 and be per‐
         missible according to the operating characteristics of the
         device.