use strict;
use warnings;
my $src_mac = 'C4:46:19:75:C1:55';
my $input = <<INPUT;
SS-ID VLAN MAC TIME IP RSSI MODE UAPSD BW GI WMOS DHCP IDENTITY
----- ---- --- ---- -- ---- ---- ----- -- -- ---- ---- --------
1-1 0 C4:46:19:75:C1:55 23m 192.168.5.253 -24 bgn no 20 S 4.9 ack*
1-2 0 5C:57:C8:69:8C:1E 3s 192.168.5.254 -38 bg no 20 L 4.8 ack*
INPUT
foreach my $line ( split /\n/, $input ) {
my ($id, $mac) = (split ' ', $line)[0,2];
if ( uc($mac) eq $src_mac ) {
print "ID = $id\n";
}
}