diff --git a/oui.py b/oui.py
new file mode 100644
index 0000000..1a16efd
--- /dev/null
+++ b/oui.py
@@ -0,0 +1,79 @@
+import sys
+from argparse import ArgumentParser
+from os import stat, mkdir
+from os.path import isfile, expanduser, isdir
+from re import compile, match as rmatch, VERBOSE
+from colorama import Fore, init
+from requests import get as r_get
+
+
+def download_oui_defs(fpath: str, force_dl=False) -> bool:
+    # file exists and is not older than 1 week
+    if (isfile(fpath) and stat(fpath).st_mtime > 604800) and not force_dl:
+        print(f"{Fore.CYAN}Definitions exist and file is less than one week old, omitting download")
+        return True
+    else:
+        if force_dl:
+            print(f"{Fore.LIGHTRED_EX}Download forced, please wait...")
+        else:
+            print(f"{Fore.CYAN}Definitions not found or too old, downloading file, please wait...")
+        r = r_get("http://standards-oui.ieee.org/oui.txt")
+        if r.status_code == 200:
+            with open(fpath, "wb") as fp:
+                fp.write(r.content)
+            return True
+        else:
+            print(f"{Fore.RED}Couldn't download oui definitions! HTTP status was {r.status_code}")
+            return False
+
+
+def lookup(fpath: str, mac: str) -> bool:
+    vendor = mac[0:8].upper().replace(":", "-")
+    pattern = compile(r"""^[0-9A-F]{2}    # match first octett at start of string
+                           [-]            # match literal -
+                           [0-9A-F]{2}    # match second otctett
+                           [-]            # match literal -
+                           [0-9A-F]{2}    # match third octett
+                           .*$            # match until end of string""", flags=VERBOSE)
+
+    with open(fpath, "rb") as fp_read:
+        for line in fp_read:
+            match = rmatch(pattern, line.decode('utf8'))
+            if match:
+                entry = match.group()
+                entry = entry.split("\t")
+                oui = entry[0].split()[0]
+                name = entry[-1]
+                if vendor == oui:
+                    print(f"{Fore.GREEN}{mac} belongs to {name}")
+                    return True
+    print(f"{Fore.RED}Couldn't find oui {vendor}")
+    return False
+
+
+if __name__ == "__main__":
+    init(autoreset=True)
+
+    parser = ArgumentParser(description="oui.py: MAC vendor lookup")
+    parser.add_argument("mac", help="The MAC address to process")
+    parser.add_argument("--force", action="store_true", help="Force download of definitions file")
+    parser.add_argument("--file", help="Override where file is stored and/or use this definition file")
+    args = parser.parse_args()
+
+    if args.file:
+        f_path = args.file
+    else:
+        if not isdir(expanduser("~/.oui")):
+            mkdir(expanduser("~/.oui"))
+        f_path = expanduser("~/.oui/oui.txt")
+
+    if not download_oui_defs(f_path, args.force):
+        sys.exit(1)
+
+    if not lookup(f_path, args.mac):
+        sys.exit(1)
+
+    sys.exit(0)
+
+
+