Which company owns MAC address prefix 58:75:21?

MAC address prefix 58:75:21 is registered to CJSC RTSoft in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 58:75:21 has a network interface built by CJSC RTSoft.

What is the OUI 58:75:21?

58:75:21 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to CJSC RTSoft. It covers every address from 58:75:21:00:00:00 to 58:75:21:FF:FF:FF, or 16,777,216 addresses in total. It is also written 58-75-21.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 58:75:21:00:00:00 that is 58:75:21 — 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 CJSC RTSoft located?

CJSC RTSoft is listed at Nikitinskaya str., 3 Moscow RU 105037 in the IEEE OUI registry entry for 58:75:21. This is the address the organization registered with the IEEE, which may differ from its current operating address.

CJSC RTSoft

MAC address prefix 58:75:21 is registered to CJSC RTSoft in the IEEE OUI registry. Any device whose MAC address begins with 58:75:21 has a network interface built by CJSC RTSoft. 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 58:75:21:00:00:00 to 58:75:21:FF:FF:FF.

OUI prefix: 58:75:21
Hyphen form: 58-75-21
MAC range: 58:75:21:00:00:00 – 58:75:21:FF:FF:FF
Addresses in block: 16,777,216
Organization: CJSC RTSoft
Address: Nikitinskaya str., 3 Moscow RU 105037
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.

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 "CJSC RTSoft"
archived source →
2026-07-17Assigned to "CJSC RTSoft"

Nearby in the registry

The prefixes assigned immediately before and after 58:75:21:

FAQ

Which company owns MAC address prefix 58:75:21?: MAC address prefix 58:75:21 is registered to CJSC RTSoft in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 58:75:21 has a network interface built by CJSC RTSoft.
What is the OUI 58:75:21?: 58:75:21 is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to CJSC RTSoft. It covers every address from 58:75:21:00:00:00 to 58:75:21:FF:FF:FF, or 16,777,216 addresses in total. It is also written 58-75-21.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 58:75:21:00:00:00 that is 58:75:21 — 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 CJSC RTSoft located?: CJSC RTSoft is listed at Nikitinskaya str., 3 Moscow RU 105037 in the IEEE OUI registry entry for 58:75:21. This is the address the organization registered with the IEEE, which may differ from its current operating address.