MacToVendorLookup 1.0.0

MacToVendorLookup

Give it a MAC address in any format, get back the hardware vendor.

The complete IEEE registry ships inside the package — 53,700 assignments, 30,650 vendors. No HTTP calls, no API key, no rate limits, no external service, and no package dependencies.

using MacToVendorLookup;

MacVendorLookup.GetVendorName("48-46-FB-11-22-33");   // "HUAWEI TECHNOLOGIES CO.,LTD"
MacVendorLookup.GetVendorName("000c.4201.0203");      // "Routerboard.com"
MacVendorLookup.GetVendorName("b827eb000001");        // "Raspberry Pi Foundation"

Install

dotnet add package MacToVendorLookup

Targets netstandard2.0 and net8.0 — runs on .NET Framework 4.6.1+, .NET Core, .NET 5+, Mono and Unity.

Usage

Everything is static. Nothing to register, inject, configure or dispose.

MacLookupResult result = MacVendorLookup.Lookup("48-46-FB-11-22-33");

result.IsValid;        // true  -- it parsed
result.IsFound;        // true  -- a vendor owns it
result.VendorName;     // "HUAWEI TECHNOLOGIES CO.,LTD"
result.NormalizedMac;  // "48:46:FB:11:22:33"
result.Oui;            // "48:46:FB"

Any format in

Colons, hyphens, dots, underscores, spaces or nothing at all — mixed separators, any casing, an optional 0x prefix, and stray whitespace. These all parse to the same address:

Bare OUI prefixes (48:46:FB) and EUI-64 addresses also work. Addresses pasted out of a router UI, an OLT export, a DHCP lease table, a spreadsheet or a log file need no cleaning up first.

Validation

Bad input never throws — the reason comes back on the result:

MacLookupResult result = MacVendorLookup.Lookup("48:46:FB:11:22");

result.IsValid;       // false
result.Error;         // MacLookupError.InvalidLength
result.ErrorMessage;  // "48:46:FB:11:22" does not hold 6, 12 or 16 hex digits, ...

IsValid means it parsed; IsFound means a vendor was resolved. A real-but-unassigned address is valid and not found. To check a string on its own: MacVendorLookup.IsValidMac(input).

Bulk

Results line up positionally with the input, so bad entries are reported in place rather than dropped:

MacLookupResult[] results = MacVendorLookup.LookupMany(macs);

Other entry points:

MacVendorLookup.LookupText(text);       // one blob: splits on newlines, commas, semicolons, pipes, tabs
MacVendorLookup.LookupManyLazy(lines);  // streams, for files too big to buffer

Summarise a batch:

foreach (var pair in results.CountByVendor())
    Console.WriteLine($"{pair.Value,6}  {pair.Key}");

Console.WriteLine(results.Summarize());
// 4812 looked up: 4790 resolved across 11 vendor(s), 18 unknown prefix, 4 invalid

Filters: WhereFound(), WhereUnknownVendor(), WhereInvalid(), WhereValid(), GroupByVendor().

Normalising

MacVendorLookup.Normalize("4846fb112233");                                // "48:46:FB:11:22:33"
MacVendorLookup.Normalize("4846fb112233", MacAddressFormat.Hyphen);       // "48-46-FB-11-22-33"
MacVendorLookup.Normalize("4846fb112233", MacAddressFormat.Dot);          // "4846.FB11.2233"
MacVendorLookup.Normalize("4846fb112233", MacAddressFormat.None, false);  // "4846fb112233"

Formats: Colon (default), Hyphen, Dot, Space, None. Invalid input returns null. This is the right way to key a database or dictionary by MAC — it collapses every spelling onto one canonical form.

Two things worth knowing

Vendor names are the registrant's legal name, verbatim from the IEEE — Routerboard.com, not MikroTik; HUAWEI TECHNOLOGIES CO.,LTD, not Huawei. Match on a fragment (Contains("huawei", StringComparison.OrdinalIgnoreCase)) rather than the exact string.

Pass the full address when you have it, not just the OUI. The IEEE splits some blocks between several companies, and only the full address identifies which one:

MacVendorLookup.GetVendorName("8C:1F:64");            // "IEEE Registration Authority"
MacVendorLookup.GetVendorName("8C:1F:64:AF:A0:01");   // "DATA ELECTRONIC DEVICES, INC"

Also check MacAddress.Parse(mac).IsLocallyAdministered if it matters: randomised phone addresses and operator-assigned ones carry no vendor meaning, whatever the registry says about that block.

Performance

A lookup takes ~115 ns and allocates nothing. The registry unpacks itself on first use (~16 ms, ~2.1 MiB); call OuiRegistry.Preload() at start-up if you would rather not pay that on a request. Everything is thread-safe — share it across a request pipeline without locking.

Details in docs/performance.md.

More

• OuiRegistry — query the data directly, search by vendor name, read DataVersion
• MacAddress — parse without the registry; octets, multicast/broadcast/local bits, comparison
• docs/data-format.md — how the embedded registry is built and refreshed
• CONTRIBUTING.md — including why vendor-data fixes go to the IEEE, not here

License

MIT — see LICENSE. Registry data is published by the IEEE Registration Authority and redistributed here as a compiled lookup table.