---
name: "cnmac"
section: "4"
platform: "openbsd"
package: "man"
version: "8.0-current-20261101"
release: "OpenBSD 8.0-current (2026-11-01)"
platforms: ["openbsd"]
url: "https://new.carta.tech/cnmac"
---

# cnmac(4)

Cavium OCTEON built-in Ethernet device

## NAME

**cnmac** – Cavium OCTEON built-in Ethernet device

## SYNOPSIS

**cnmac\* at octgmx?**

## DESCRIPTION

The **cnmac** driver supports built-in Ethernet ports on Cavium OCTEON CN30xx, Cavium OCTEON Plus CN50xx, Cavium OCTEON II CN61xx, and Cavium OCTEON III CN71xx system on chips. Among the routers based on these chips are the following:

-

  D-Link DSR-500

-

  Netgear ProSecure UTM25

-

  Portwell CAM-0100

-

  Rhino Labs Inc. SDNA Shasta

-

  Rhino Labs Inc. SDNA-7130

-

  Ubiquiti Networks EdgeRouter

-

  Ubiquiti Networks EdgeRouter 4

-

  Ubiquiti Networks EdgeRouter 6

-

  Ubiquiti Networks EdgeRouter LITE

-

  Ubiquiti Networks EdgeRouter PoE

-

  Ubiquiti Networks EdgeRouter PRO

-

  Ubiquiti Networks UniFi Security Gateway

-

  Ubiquiti Networks UniFi Security Gateway PRO-4

The **cnmac** driver supports TCP/UDP checksum offload on IPv4/IPv6 reception and transmission, and IPv4 checksum offload on reception. The driver additionally supports jumbo frames.

## SEE ALSO

[arp(4)](/arp/4.md), [ifmedia(4)](/ifmedia/4.md), [intro(4)](/intro/4.md), [netintro(4)](/netintro/4.md), [octgmx(4)](/octgmx/4.md), [hostname.if(5)](/hostname.if/5.md), [ifconfig(8)](/ifconfig/8.md)

## HISTORY

The **cnmac** driver first appeared in OpenBSD 5.4.

## AUTHORS

The **cnmac** driver was written by Internet Initiative Japan Inc.