pfSense

In the DHCP Leases table, we see the assigned manufacturer displayed beside each MAC address.
This would be extremely useful information to have on the ARP Table display also.

Here's a diff that implements it. I haven't been a PHP programmer for 20 years, I don't claim this is production-quality.

--- diag_arp-orig.php   2021-06-11 15:31:39.918428000 -0500
+++ diag_arp.php        2021-06-11 15:39:44.624554000 -0500
@@ -38,6 +38,9 @@
 require_once("guiconfig.inc");
 require_once("diag_arp.inc");

+// Load MAC-Manufacturer table
+$mac_man = load_mac_manufacturer_table();
+
 // delete arp entry
 if (isset($_POST['deleteentry'])) {
        $ip = $_POST['deleteentry'];
@@ -139,7 +142,20 @@
                        <tr>
                                <td><?=$entry['interface']?></td>
                                <td><?=$entry['ip-address']?></td>
-                               <td><?=$entry['mac-address']?></td>
+                               <td><?=$entry['mac-address']?>
+                               <?php
+                                       $mac_hi = strtoupper($entry['mac-address'][0] . $entry['mac-address'][1] . $entry['mac-address'][3] . $entry['mac-address'][4] . $entry['mac-address'][6] . $entry['mac-address'][7]);
+                                       if (isset($mac_man[$mac_hi])):
+                               ?>
+                                               (<?=htmlspecialchars($mac_man[$mac_hi])?>)
+                               <?php 
+                                       else:
+                               ?>
+                                       (unknown vendor)
+                               <?php
+                                       endif;
+                               ?>
+                               </td>
                                <td><?=$entry['dnsresolve']?></td>
                                <td><?=$entry['expires']?></td>
                                <td><?=$entry['type']?></td>