RSU(4)

💖 RSU(4) 💖

okay bestie, sit down, hydrate, because we're about to talk about your rsu driver — that's the Realtek RTL8188SU/RTL8192SU USB IEEE 802.11b/g/n wireless network device situation. this lives in the Kernel Interfaces Manual, and yes it's giving "I am the entire personality of your USB wifi stick." 🦋

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✨ SYNOPSIS ✨

so if you wanna bake this driver directly into your kernel, you drop these lines into your kernel configuration file:

device ehci
device uhci
device ohci
device usb
device rsu
device rsufw
device wlan

orrrr — and this is the lowkey easier route — if you'd rather load it as a module at boot time, you put these in loader.conf(5):

if_rsu_load="YES"
rsu-rtl8712fw_load="YES"

no cap, that's it. 🫶

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🌸 DESCRIPTION 🌸

the rsu driver is out here supporting USB 2.0 wireless network devices built on the Realtek RTL8188SU, RTL8191SU and RTL8192SU chipsets. let's meet the girlies:

• the RTL8188SU is a highly integrated 802.11n adapter that combines a MAC, a 1T1R capable baseband and an RF in a single chip. it operates in the 2GHz spectrum only. one chip, whole personality. 💅
• the RTL8191SU is a highly integrated multiple-in, single-out (MISO) 802.11n adapter that combines a MAC, a 1T2R capable baseband and an RF in a single chip. it operates in the 2GHz spectrum only.
• the RTL8192SU is a highly integrated multiple-in, multiple-out (MIMO) 802.11n adapter that combines a MAC, a 2T2R capable baseband and an RF in a single chip. it operates in the 2GHz spectrum only. main character energy fr fr.

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🎀 the modes she can serve

these are the modes the rsu 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. the default one. the moment. ✨
• 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. she's nosy and we love her. 👀

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the rsu driver can be configured to use Wired Equivalent Privacy (WEP) or Wi-Fi Protected Access (WPA-PSK and WPA2-PSK). WPA is the de facto 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. bestie. please. WEP is not the vibe. do not. 🙈

the rsu driver can be configured at runtime with ifconfig(8). iconic behavior honestly.

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📁 FILES 📁

• /usr/share/doc/legal/realtek.LICENSE — rsu firmware license

the driver needs at least version 1.2 of the following firmware file, which is loaded when an interface is attached:

/boot/kernel/rsu-rtl8712fw.ko

so like. version 1.2 or newer. don't show up with 1.1. 💀

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🔥 HARDWARE 🔥

the rsu driver provides support for Realtek RTL8188SU/RTL8192SU USB IEEE 802.11b/g/n wireless network adapters, including:

ASUS USB-N10
Belkin F7D1101 v1
D-Link DWA-131 A1
EDUP EP-MS150N(W)
Edimax EW-7622UMN
Hercules HWGUn-54
Hercules HWNUm-300
Planex GW-USNano
Sitecom WL-349 v1
Sitecom WL-353
Sweex LW154
TRENDnet TEW-646UBH
TRENDnet TEW-648UB
TRENDnet TEW-649UB

if your stick is on this list, she's supported, periodt. if not… vibe check your shopping cart next time 🛒✨

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🧚 EXAMPLES 🧚

join an existing BSS network (i.e., connect to an access point):

ifconfig wlan create wlandev rsu0 inet 192.168.0.20 \
    netmask 0xffffff00

join a specific BSS network with network name “my_net”:

ifconfig wlan create wlandev rsu0 ssid my_net up

join a specific BSS network with 64-bit WEP encryption:

ifconfig wlan create wlandev rsu0 ssid my_net \
        wepmode on wepkey 0x1234567890 weptxkey 1 up

(that last one is the WEP example. see above re: WEP. I'm just the messenger 💀)

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😭 DIAGNOSTICS 😭

• %s: failed load firmware of file rsu-rtl8712fw — for some reason, the driver was unable to read the microcode file from the filesystem. the file might be missing or corrupted. check your file bestie, she's not there. 😭
• 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. it's giving red flag. 🚩

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👑 SEE ALSO 👑

intro(1), netintro(4), rsufw(4), usb(4), wlan(4), arp(8), hostapd(8), ifconfig(8), wpa_supplicant(8)

read them. they ate. 📚✨

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🌈 HISTORY 🌈

the rsu driver first appeared in OpenBSD 4.9 and FreeBSD 10.0. a legend since day one. ⭐

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💜 AUTHORS 💜

the rsu driver was written by Damien Bergamini <damien@openbsd.org> and ported by Rui Paulo <rpaulo@freebsd.org>. the 802.11n support was added by Adrian Chadd <adrian@freebsd.org>.

thank you to the girlies who built her 🫶👑

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⚠️ CAVEATS ⚠️

• the rsu driver currently does not support 802.11n transmit aggregation, either A-MSDU or A-MPDU. so no, she's not doing that. 💅
• the rsu driver does not capture management frames in non-monitor modes; without this limitation some firmware functions (e.g., 'join bss') will not work properly. it's a whole tradeoff, iykyk.

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and that's the page, bestie!! 💖 this one's from the Debian crew, dated April 4, 2018, and it's filed as RSU(4) — go forth, plug in your USB stick, and slay. 🎀✨🦋