in network tab, decode and id "Private MAC" addresses

In RFC7042 section 2.1 specifies the “Local bit”:
    The Local bit is zero for globally unique EUI-48 identifiers
    assigned by the owner of an OUI or owner of a longer prefix.
    If the Local bit is a one, the identifier has been considered
    by IEEE 802 to be a local identifier under the control of the
    local network administrator...

Both iOS and Android use this as part of their randomized anti-tracking
mechanisms. So, display it to admins, so they can tell what device
is their phone.

Signed-off-by: Robin Getz <rgetz503@gmail.com>

Author: rgetz

scripts/js/network.js

@@ -183,6 +183,13 @@ $(() => {
         $("td:eq(1)", row).html(
           utils.escapeHtml(data.hwaddr) + "<br>" + utils.escapeHtml(data.macVendor)
         );
+      } else if (data.hwaddr && data.hwaddr.includes(":")) {
+        const firstOctet = Number.parseInt(data.hwaddr.split(":")[0], 16);
+        // Check whether the 2 (0x02) bit is set using arithmetic to avoid bitwise operators:
+        if (Math.floor(firstOctet / 2) % 2 === 1) {
+          const cell = $("td:eq(1)", row);
+          cell.html(cell.html() + "<br>Private MAC");
+        }
       }
 
       // Make mock MAC addresses italics and add title