Which company owns MAC address prefix 00:18:09?

MAC address prefix 00:18:09 is registered to CRESYN in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 00:18:09 has a network interface built by CRESYN.

What is the OUI 00:18:09?

00:18:09 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to CRESYN. It covers every address from 00:18:09:00:00:00 to 00:18:09:FF:FF:FF, or 16,777,216 addresses in total. It is also written 00-18-09.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 00:18:09:00:00:00 that is 00:18:09 — and look that prefix up in the IEEE OUI registry. If the second-lowest bit of the first octet is set, the address is locally administered (a randomized or private MAC), which belongs to no manufacturer and will not resolve; modern phones and laptops use these by default on each network.

Where is CRESYN located?

CRESYN is listed at 8-22,Jamwon-dong Seoul Seocho-Gu KR #137-902 in the IEEE OUI registry entry for 00:18:09. This is the address the organization registered with the IEEE, which may differ from its current operating address.

How many MAC prefixes does CRESYN own?

CRESYN holds 5 OUI prefixes in the IEEE registry, of which 00:18:09 is one. A device made by CRESYN could carry a MAC address from any of them.

CRESYN

MAC address prefix 00:18:09 is registered to CRESYN in the IEEE OUI registry. Any device whose MAC address begins with 00:18:09 has a network interface built by CRESYN. This prefix (the OUI, or Organizationally Unique Identifier) is assigned by the IEEE and is the first three octets of the address — it covers every MAC from 00:18:09:00:00:00 to 00:18:09:FF:FF:FF.

OUI prefix: 00:18:09
Hyphen form: 00-18-09
MAC range: 00:18:09:00:00:00 – 00:18:09:FF:FF:FF
Addresses in block: 16,777,216
Organization: CRESYN
Address: 8-22,Jamwon-dong Seoul Seocho-Gu KR #137-902
Source: IEEE OUI registry

Have a full MAC address? Look it up— we'll also tell you if it's a randomized (private) address rather than a real manufacturer prefix.

Other prefixes from CRESYN

CRESYN holds 5 OUI prefixes in total. A device with this exact prefix could just as well carry any of these:

Assignment history (2)

The IEEE registry publishes current state only — this is the change record we've kept since we started tracking it daily.

2016-07-29Assigned to "CRESYN"
archived source →
2026-07-17Assigned to "CRESYN"

Nearby in the registry

The prefixes assigned immediately before and after 00:18:09:

FAQ

Which company owns MAC address prefix 00:18:09?: MAC address prefix 00:18:09 is registered to CRESYN in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 00:18:09 has a network interface built by CRESYN.
What is the OUI 00:18:09?: 00:18:09 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to CRESYN. It covers every address from 00:18:09:00:00:00 to 00:18:09:FF:FF:FF, or 16,777,216 addresses in total. It is also written 00-18-09.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 00:18:09:00:00:00 that is 00:18:09 — and look that prefix up in the IEEE OUI registry. If the second-lowest bit of the first octet is set, the address is locally administered (a randomized or private MAC), which belongs to no manufacturer and will not resolve; modern phones and laptops use these by default on each network.
Where is CRESYN located?: CRESYN is listed at 8-22,Jamwon-dong Seoul Seocho-Gu KR #137-902 in the IEEE OUI registry entry for 00:18:09. This is the address the organization registered with the IEEE, which may differ from its current operating address.
How many MAC prefixes does CRESYN own?: CRESYN holds 5 OUI prefixes in the IEEE registry, of which 00:18:09 is one. A device made by CRESYN could carry a MAC address from any of them.