http://www.perlmonks.org?node_id=804580


in reply to Re^6: Net::Pcap with wireless
in thread Net::Pcap with wireless

in khen1950fx's code my $dev  = find_device($ARGV[0]); says that the name "wifi" printed in the error message is retrieved from $ARGV[0]. You call your device wlan0 not wifi. Maybe try wlan0 as the argument?