RSU(4)

📦
version 15.1 · 3 versions
, in freebsd 15.1, nixpkgs unstable

💅 RSU(4) — like, the Realtek RTL8188SU/RTL8192SU USB IEEE 802.11b/g/n wireless network driver, bestie

okay so real talk, this is a page from the Kernel Interfaces Manual and honestly? it's giving "your wifi card's whole origin story." let's get into it 🫶

✨ NAME ✨

rsu — the Realtek RTL8188SU/RTL8192SU USB IEEE 802.11b/g/n wireless network driver. say it with me: w i r e l e s s. we're cordless now 💅

🌸 SYNOPSIS 🌸

so if you want this driver baked into the kernel (main character energy, no modules), you drop these lines into your kernel configuration file:

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

orrrr, if you'd rather load it as a module at boot time (respectable choice, ngl), put these lines in loader.conf(5):

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

💖 DESCRIPTION 💖

okay so the rsu driver has your back for USB 2.0 wireless network devices based on the Realtek RTL8188SU, RTL8191SU and RTL8192SU chipsets. iconic lineup honestly.

  • RTL8188SU — 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. one vibe.
  • RTL8191SU — 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. MISO! like the soup. (it is not the soup.)
  • RTL8192SU — 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. MIMO means more antennas more problems? no, more antennas more slay.

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. it's the standard, the blueprint, the blueprint-y blueprint.
  • 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. sneaky. observant. we love her 🙈

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. like... seriously bestie, WEP is not it. WEP is the flip phone of encryption. cute in a museum, tragic in real life 😭

the rsu driver can be configured at runtime with ifconfig(8). live your life, change settings on the fly ✨

🦋 HARDWARE 🦋

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

  • ASUS USB-N10
  • ASUS WL-167G V3
  • 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
  • Sitecom WLA-1100 v1001
  • Sweex LW154
  • TRENDnet TEW-646UBH
  • TRENDnet TEW-648UB
  • TRENDnet TEW-649UB

if your dongle is on this list it's literally invited to the party 🎀

🎀 FILES 🎀

  • /usr/share/doc/legal/realtek.LICENSE — the rsu firmware license. legal stuff, read it, be responsible, periodt.

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
ngl, that "at least version 1.2" bit matters. old firmware? no thoughts, head empty, driver sad.

⭐ EXAMPLES ⭐

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

ifconfig wlan create wlandev rsu0 inet 192.0.2.20/24

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

(and hey — remember the WEP warning up top. i'm just the messenger 💀)

🔥 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. bestie. bestie. check the file. it's right there in FILES. go look. 😭
  • 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. key word should. if you see this, something's off in the universe 🌈

💜 SEE ALSO 💜

intro(1), netintro(4), rsufw(4), usb(4), wlan(4), networking(7), arp(8), hostapd(8), ifconfig(8), wpa_supplicant(8)

the whole friend group, fr fr 🫶

👑 HISTORY 👑

the rsu driver first appeared in OpenBSD 4.9 and FreeBSD 10.0. ancient. legendary. she's been around.

🌈 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>. absolute icons, all three of them, no cap 💅

💀 CAVEATS 💀

  • the rsu driver currently does not support 802.11n transmit aggregation, either A-MSDU or A-MPDU. it's not a bug it's a boundary.
  • 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. so like... she could but she won't, and honestly that's for the best. main character restraint 🌸

okay that's the whole page, you're officially educated 💖 this lil beauty comes to you from Debian, dated April 1, 2025 — no joke, that's the actual date, and the driver would like you to know she ate. bye bestie, go configure your wifi 🧚✨

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