RTWN(4) Kernel Interfaces Manual RTWN(4) NAME rtwn -- Realtek IEEE 802.11n/ac wireless network driver SYNOPSIS options RTWN_DEBUG options RTWN_WITHOUT_UCODE To compile this driver into the kernel, place the following lines in your kernel configuration file: device rtwn device rtwnfw device rtwn_usb device rtwn_pci device wlan device firmware Alternatively, to load the driver as a module at boot time, place following lines in loader.conf(5): if_rtwn_pci_load="YES" if_rtwn_usb_load="YES" DESCRIPTION The rtwn driver provides support for 802.11n/ac wireless network PHYs sup- plied by rtwn_pci(4) and rtwn_usb(4). The rtwn driver supports station, adhoc, hostap and monitor mode operation. There are no limitations for number of monitor mode virtual interfaces; in addition to any other virtual interface one station interface can be added (Note: RTL8821AU supports two non-monitor mode interfaces at the same time). All chips have hardware support for WEP, AES-CCM and TKIP encryption. The rtwn driver can be configured at runtime with ifconfig(8). HARDWARE The rtwn driver supports USB and PCI devices with the following chipsets: * Realtek 802.11n wireless 8188e (RTL8188E) * Realtek 802.11n wireless 8192c (RTL8192C) * Realtek 802.11n wireless 8192e (RTL8192E) * Realtek 802.11n wireless 8723b (RTL8723B) * Realtek 802.11ac wireless 8812a (RTL8812A) * Realtek 802.11ac wireless 8821a (RTL8821A) For specific devices, see rtwn_pci(4) and rtwn_usb(4). FILES /usr/share/doc/legal/realtek.LICENSE rtwn firmware license The driver (if not compiled with options RTWN_WITHOUT_UCODE) may use fol- lowing firmware files, which are loaded when an interface is brought up: /boot/kernel/rtwn-rtl8188eefw.ko /boot/kernel/rtwn-rtl8188eufw.ko /boot/kernel/rtwn-rtl8192cfwE_B.ko /boot/kernel/rtwn-rtl8192cfwE.ko /boot/kernel/rtwn-rtl8192cfwT.ko /boot/kernel/rtwn-rtl8192cfwU.ko /boot/kernel/rtwn-rtl8192eufw.ko /boot/kernel/rtwn-rtl8723bufw.ko /boot/kernel/rtwn-rtl8812aufw.ko /boot/kernel/rtwn-rtl8821aufw.ko EXAMPLES Join an existing BSS network (i.e., connect to an access point): ifconfig wlan create wlandev rtwn0 inet 192.0.2.20/24 Join a specific BSS network with network name my_net: ifconfig wlan create wlandev rtwn0 ssid my_net up Join a specific BSS network with 64-bit WEP encryption: ifconfig wlan create wlandev rtwn0 ssid my_net \ wepmode on wepkey 0x1234567890 weptxkey 1 up Create an IBSS network with 128-bit WEP encryption on the channel 4: ifconfig wlan create wlandev rtwn0 wlanmode adhoc ssid my_net \ wepmode on wepkey 0x01020304050607080910111213 weptxkey 1 \ channel 4 Join/create an 802.11b IBSS network with network name my_net: ifconfig wlan0 create wlandev rtwn0 wlanmode adhoc ifconfig wlan0 inet 192.0.2.20/24 ssid my_net mode 11b Create a host-based access point: ifconfig wlan0 create wlandev rtwn0 wlanmode hostap ifconfig wlan0 inet 192.0.2.20/24 ssid my_ap LOADER TUNABLES Tunables can be set at the loader(8) prompt before booting the kernel or stored in loader.conf(5). dev.rtwn.%d.hwcrypto This tunable controls how key slots are assigned: 0 - disable h/w crypto support. Features that require access to frame contents (e.g., TCP/UDP/IP Rx checksum validation) will not work; 1 - use h/w crypto support for pairwise keys only; 2 - use h/w crypto support for all keys; may not work for multi-vap configurations. By default it is set to 1. dev.rtwn.%d.ratectl This tunable switches between rate control implementations: 0 - no rate control; 1 - driver sends 'tx complete' reports to net80211; algorithm is controlled via net80211; 2 - firmware-based rate control. By default it is set to 1; however driver may choose another algo- rithm in case if it is not implemented Currently selected algorithm is reported via dev.rtwn.%d.ratectl_selected read-only OID. dev.rtwn.%d.rx_buf_size (USB only) Controls size of temporary Rx buffer; smaller buffer size may increase number of interrupts. DIAGNOSTICS rtwn%d: could not read efuse byte at address 0x%x rtwn%d: %s: cannot read rom, error %d There was an error while reading ROM; device attach will be aborted. This should not happen. rtwn%d: failed loadfirmware of file %s For some reason, the driver was un- able to read the microcode file from the filesystem. The file might be missing or corrupted. The driver will disable firmware-dependent features. rtwn%d: wrong firmware size (%zu) rtwn%d: %s: failed to upload firmware %s (error %d) rtwn%d: timeout waiting for firmware readiness Firmware upload failed; the file might be corrupted. The driver will disable firmware-dependent fea- tures. This should not happen. rtwn%d: device timeout A frame dispatched to the hardware for transmission did not complete in time. The driver will reset the hardware. This should not happen. SEE ALSO intro(4), netintro(4), rtwn_pci(4), rtwn_usb(4), rtwnfw(4), wlan(4), wlan_amrr(4), wlan_ccmp(4), wlan_tkip(4), wlan_wep(4), wlan_xauth(4), net- working(7), hostapd(8), ifconfig(8), wpa_supplicant(8) HISTORY The urtwn driver first appeared in OpenBSD 4.9 and FreeBSD 10.0; the rtwn driver first appeared in OpenBSD 5.8 and FreeBSD 11.0. AUTHORS The rtwn driver was initially written by Stefan Sperling <stsp@openbsd.org> and ported by Kevin Lo <kevlo@FreeBSD.org>. It was based on the urtwn dri- ver written by Damien Bergamini <damien.bergamini@free.fr>. BUGS The rtwn driver currently does not implement firmware-based rate control. The RTL8723BU seems to depend on some firmware commands for antenna setup. Hence, it does not work without firmware. FreeBSD 16.0 CURRENT September 1, 2026 RTWN(4)
NAME | SYNOPSIS | DESCRIPTION | HARDWARE | FILES | EXAMPLES | LOADER TUNABLES | DIAGNOSTICS | SEE ALSO | HISTORY | AUTHORS | BUGS
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