diff --git a/hostid.py b/hostid.py
new file mode 100644
index 0000000..2b4038e
--- /dev/null
+++ b/hostid.py
@@ -0,0 +1,13 @@
+import re
+from functools import reduce
+
+def mac_to_hostid(mac):
+  int_mac = list(map(lambda x: int(x, 16), mac.split(":")))
+  int_mac[0] ^= 2
+  bytes = map(lambda x: "%02x" % x, int_mac[0:3] + [0xff, 0xfe] + int_mac[3:])
+  return reduce(lambda a, i:
+                  [a[0] + ("" if i == 0 else ":") + a[1] + a[2]] + a[3:],
+                range(0, 4),
+                [""] + list(bytes)
+               )
+