ATH(4) | Device Drivers Manual | ATH(4) |
ath
— Atheros IEEE
802.11a/b/g wireless network device with GPIO
ath* at pci? dev ? function ?
ath* at cardbus? dev ? function ?
gpio* at ath?
The ath
driver provides support for
wireless network devices based on the Atheros AR5210, AR5211, and AR5212
chips.
All host/device interaction is via DMA. The
ath
driver encapsulates all IP and ARP traffic as
802.11 frames, though it can receive either 802.11 or 802.3 frames. Transmit
speed and operating mode is selectable and depends on the specific
chipset.
Support for the various devices is as follows:
The actual transmit speed used is dependent on signal quality and the “rate control” algorithm employed by the driver.
These are the modes the ath
driver can
operate in:
The ath
driver can be configured to use
Wired Equivalent Privacy (WEP) or Wi-Fi Protected Access (WPA-PSK and
WPA2-PSK). WPA is the current encryption standard for wireless networks. It
is strongly recommended that WEP not be used as the sole mechanism to secure
wireless communication, due to serious weaknesses in it.
AR5211 and AR5212 support the AES, TKIP, and Michael cryptographic operations required for WPA in hardware but at this time the driver does not support them.
In BSS mode, the driver supports powersave mode, which can be enabled via ifconfig(8).
The ath
driver can be configured at
runtime with ifconfig(8) or
on boot with
hostname.if(5).
Devices supported by the ath
driver come
in either CardBus or Mini PCI packages. Wireless cards in CardBus slots may
be inserted and ejected on the fly.
The following cards are among those supported by the
ath
driver:
Card | Chip | Bus | Standard |
3Com 3CRPAG175 | AR5212 | CardBus | a/b/g |
Cisco AIR-CB21AG | AR5212 | CardBus | a/b/g |
D-Link DWL-A650 | AR5210 | CardBus | a |
D-Link DWL-AB650 | AR5211 | CardBus | a/b |
D-Link DWL-A520 | AR5210 | PCI | a |
Elecom LD-WL54 | AR5211 | CardBus | a |
IBM 11ABG WL LAN | AR5212 | Mini PCI | a/b/g |
Linksys WPC51AB | AR5211 | CardBus | a/b |
Netgear WAB501 | AR5211 | CardBus | a/b |
Planet WL-3560 | AR5211 | CardBus | a/b/g |
Proxim Skyline 4030 | AR5210 | CardBus | a |
Proxim Skyline 4032 | AR5210 | PCI | a |
Senao NL-5354MP | AR5212 | Mini PCI | a/b/g |
SMC SMC2735W | AR5210 | CardBus | a |
Sony PCWA-C500 | AR5210 | CardBus | a |
Wistron CM9 | AR5212 | Mini PCI | a/b/g |
The following example scans for available networks:
# ifconfig ath0 scan
The following hostname.if(5) example configures ath0 to join network “mynwid”, using WPA key “mywpakey”, obtaining an IP address using DHCP:
nwid mynwid wpakey mywpakey dhcp
The following hostname.if(5) example creates a host-based access point on boot:
mediaopt hostap nwid mynwid wpakey mywpakey inet 192.168.1.1 255.255.255.0
arp(4), cardbus(4), gpio(4), ifmedia(4), intro(4), netintro(4), pci(4), hostname.if(5), gpioctl(8), hostapd(8), ifconfig(8)
The ath
device driver first appeared in
FreeBSD 5.2 using a binary-only HAL module which was
ported to NetBSD 2.0. The driver using a free
HAL-replacement first appeared in OpenBSD 3.7.
The ath
driver was written by
Sam Leffler, and was ported to
OpenBSD by Reyk Floeter
<reyk@openbsd.org>
who also wrote a free replacement of the binary-only HAL.
Different regulatory domains may not be able to communicate with each other with 802.11a as different regulatory domains do not necessarily have overlapping channels.
Host AP mode doesn't support power saving. Clients attempting to use power saving mode may experience significant packet loss (disabling power saving on the client will fix this).
Performance in lossy environments is suboptimal. The algorithm used to select the rate for transmitted packets is very simplistic. There is no software retransmit; only hardware retransmit is used. Contributors are encouraged to replace the existing rate control algorithm with a better one.
The driver does not fully enable power-save operation of the chip; consequently power use is suboptimal.
Operation in the 2GHz band is restricted to 11b mode because the driver does not support running the hardware in 11g mode.
March 29, 2019 | OpenBSD-6.5 |