Convert all MAC addresses into their vendor names, pipe macs in or out, resolve lots of macs locally, quickly

macs.pl

#!/usr/bin/perl

# if it doesn't work, try:
# sudo cpan install Text::CSV 

use strict;
use warnings;
use File::stat;
use Text::CSV;

my $macs_url = 'https://standards-oui.ieee.org/oui/oui.csv';
my $macs_file = 'Downloads/oui.csv';

# Hash to store MAC address prefixes and their corresponding vendor names
my %mac_vendors;

# Function to download the MAC address vendor list using curl if it doesn't exist or is outdated
sub download_mac_vendor_list {
    if (!-e $macs_file || is_outdated($macs_file)) {
        print "Downloading the MAC address vendor list...\n";
        system("curl -o $macs_file $macs_url");
        if ($? != 0) {
            die "Failed to download the MAC address vendor list.\n";
        }
    }
}

# Function to check if a file is more than 3 months old
sub is_outdated {
    my ($filename) = @_;
    my $st = stat($filename);
    my $three_months_ago = time() - (3 * 30 * 24 * 60 * 60); # 3 months in seconds
    return $st->mtime < $three_months_ago;
}

sub lookup_mac_vendor {
    my ($mac) = @_;
    $mac =~ s/[:-]//g; # Remove colons and hyphens from the input MAC address
    my $vendor = $mac_vendors{uc(substr($mac, 0, 6))}; # 6 characters to match without colons and hyphens
    return $vendor ? substr($mac, 6, 6) . " $vendor" : $mac;
}

sub main {
    download_mac_vendor_list();

    # Read the MAC address vendor list and populate the hash using CSV parser
    my $csv = Text::CSV->new({ binary => 1 }) or die "Cannot use CSV: " . Text::CSV->error_diag();
    open(my $vendor_fh, '<', $macs_file) or die "Couldn't open file $macs_file: $!";
    while (my $row = $csv->getline($vendor_fh)) {
        next if @$row < 4; # Skip invalid rows
        my (undef, $prefix, $vendor, undef) = @$row;
        $mac_vendors{uc($prefix)} = $vendor;
    }
    close($vendor_fh);

    # Main loop to read from stdin and substitute MAC addresses with vendor names
    while (<>) {
        s/([0-9A-Fa-f]{12})/lookup_mac_vendor($&)/ge ||
        s/(([0-9A-Fa-f]{2}[-:]){5}[0-9A-Fa-f]{2})/lookup_mac_vendor($&)/ge;
        print;
    }
}

main();