---
name: "urtw"
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/urtw"
---

# urtw(4)

Realtek RTL8187L/RTL8187B USB IEEE 802.11b/g wireless network device

## NAME

**urtw** – Realtek RTL8187L/RTL8187B USB IEEE 802.11b/g wireless network device

## SYNOPSIS

**urtw\* at uhub? port ?**

## DESCRIPTION

The **urtw** driver supports USB 802.11b/g wireless adapters based on the Realtek RTL8187L and RTL8187B.

These are the modes the **urtw** driver can operate in:

- BSS mode

  Also known as *infrastructure* mode, this is used when associating with an access point, through which all traffic passes. This mode is the default.

- monitor mode

  In this mode the driver is able to receive packets without associating with an access point. This disables the internal receive filter and enables the card to capture packets from networks which it wouldn't normally have access to, or to scan for access points.

The **urtw** driver can be configured to use Wired Equivalent Privacy (WEP) or Wi-Fi Protected Access (WPA1 and WPA2). WPA2 is currently the most secure encryption standard for wireless networks supported by OpenBSD. It is strongly recommended that neither WEP nor WPA1 are used as the sole mechanism to secure wireless communication, due to serious weaknesses. WPA1 is disabled by default and may be enabled using the option "**wpaprotos** *wpa1,wpa2*". For standard WPA networks which use pre-shared keys (PSK), keys are configured using the "**wpakey**" option. WPA-Enterprise networks require use of the wpa\_supplicant package. The **urtw** driver relies on the software 802.11 stack for both encryption and decryption of data frames.

The **urtw** driver can be configured at runtime with [ifconfig(8)](/ifconfig/8.md) or on boot with [hostname.if(5)](/hostname.if/5.md).

## HARDWARE

The following adapters should work:

- Alfa AWUS036H

  - ASUS P5B Deluxe

  - Belkin F5D7050E

  - Digitus DN-7003GT

  - Linksys WUSB54GC v2

  - Netgear WG111v2

  - Netgear WG111v3

  - Shuttle XPC Accessory PN20

  - Sitecom WL-168 v1

  - Sitecom WL-168 v4

  - Surecom EP-9001-g rev 2A

  - TRENDnet TEW-424UB V3.xR

  ## EXAMPLES

The following example scans for available networks:

```
# ifconfig urtw0 scan
```

The following [hostname.if(5)](/hostname.if/5.md) example configures urtw0 to join network “mynwid”, using WPA key “mywpakey”, obtaining an IP address using DHCP:

```
join mynwid wpakey mywpakey
inet autoconf
```

## 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)

Realtek Semiconductor: **https://www.realtek.com/en**

## HISTORY

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

## AUTHORS

The **urtw** driver was written by Weongyo Jeong ⟨*weongyo@FreeBSD.org*⟩.