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

# mos(4)

MosChip MCS7730/7830/7832 10/100 USB Ethernet device

## NAME

**mos** – MosChip MCS7730/7830/7832 10/100 USB Ethernet device

## SYNOPSIS

**mos\*   at uhub?**

## DESCRIPTION

The **mos** driver provides support for USB Ethernet adapters based on the MosChip MCS7730, MCS7830 and MCS7832 USB 2.0 chipsets, including the following:

- Delock 61147

  - Sitecom LN-030

  - Syba SY-U2LAN

  All adapters operate with either USB 1.x or USB 2.0 controllers, though performance with 1.x controllers is limited since the USB 1.x standard specifies a maximum transfer speed of 12Mbps. Users with USB 1.x controllers should therefore not expect to actually achieve 100Mbps speeds with these devices.

A 64-bit multicast hash table is supported, single perfect filter entry for the station address, all-multicast mode, and promiscuous mode. Packets are received and transmitted over separate USB bulk transfer endpoints.

The **mos** driver supports the following media types:

- autoselect

  Enable autoselection of the media type and options (this is the default). The user can manually override the autoselected mode by adding media options to the appropriate [hostname.if(5)](/hostname.if/5.md) file.

- 10baseT

  Set 10Mbps operation.

- 100baseTX

  Set 100Mbps (Fast Ethernet) operation.

The **mos** driver supports the following media options:

- full-duplex

  Force full-duplex operation.

- half-duplex

  Force half-duplex operation.

For more information on configuring this device, see [ifconfig(8)](/ifconfig/8.md).

## DIAGNOSTICS

- mos0: watchdog timeout

  A packet was queued for transmission and a transmit command was issued, however the device failed to acknowledge the transmission before a timeout expired.

- mos0: no memory for rx list

  The driver failed to allocate an mbuf for the receiver ring.

## SEE ALSO

[arp(4)](/arp/4.md), [ifmedia(4)](/ifmedia/4.md), [intro(4)](/intro/4.md), [netintro(4)](/netintro/4.md), [usb(4)](/usb/4.md), [hostname.if(5)](/hostname.if/5.md), [ifconfig(8)](/ifconfig/8.md) *MosChip India*, https://moschip.com.

## HISTORY

The **mos** device driver first appeared in OpenBSD 4.5.

## AUTHORS

The **mos** driver was written by Johann Christian Rode ⟨*jcrode@gmx.net*⟩.