Saturday, May 17, 2025

FreeBSD and Edimax N150 Wi-Fi USB network interface

I have found old Edimax N150 Wi-Fi USB network interface and would like to use it in FreeBSD 14.2. for some IoT project. I have not used Wi-Fi on FreeBSD for ages, so let's try it.

It is worth to mention that Wi-Fi network interface can be in three different modes

  • Station (client) - ifconfig wlan0 mode sta
  • Monitor - ifconfig wlan0 mode monitor
  • Access Point - ifconfig wlan0 mode hostap

Access Point (ifconfig wlan0 mode hostap) is great in situations you would like to allow multiple Stations to connect, but the rtwn driver in FreeBSD does not support Access Point (hostap) mode.  

Monitor mode on a wireless interface (ifconfig wlan0 mode monitor) is a special mode used primarily for passive packet capturing and wireless debugging, not for normal network communication. This mode should be supported by rtwn driver in FreeBSD, but I did not tested.

Station/Client (sta) mode is supported and it is actually the only mode we will cover in this blog post.

Let's do a configuration, setup, and some performance tests ...

Configuration and Setup

wlan0 as Wi-Fi network interface

By checking dmesg, we realize that Edimax N150 is actually using Realtek RTL8188CUS chip, which should be supported by the rtwn_usb driver in FreeBSD.

 rtwn0 on uhub1  
 rtwn0: <Realtek 802.11n WLAN Adapter, class 0/0, rev 2.00/2.00, addr 2> on usbus0  
 rtwn0: MAC/BB RTL8188CUS, RF 6052 1T1R

It is important to say, taht Realtek RTL8188CUS does NOT support 5 GHz Wi-Fi, therefore only 2.4 GHz band can be used.

What you also realize is the fact, that we do not see any Wi-Fi network interface in ifconfig list of interfaces ...

 root@kuna:~ # ifconfig -a  
 em0: flags=1008843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST,LOWER_UP> metric 0 mtu 1500  
     options=4e524bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,LRO,WOL_MAGIC,VLAN_HWFILTER,VLAN_HWTSO,RXCSUM_IPV6,TXCSUM_IPV6,HWSTATS,MEXTPG>  
     ether b8:ae:ed:71:63:df  
     inet 192.168.4.188 netmask 0xffffff00 broadcast 192.168.4.255  
     media: Ethernet autoselect (1000baseT <full-duplex>)  
     status: active  
     nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>  
 lo0: flags=1008049<UP,LOOPBACK,RUNNING,MULTICAST,LOWER_UP> metric 0 mtu 16384  
     options=680003<RXCSUM,TXCSUM,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6>  
     inet 127.0.0.1 netmask 0xff000000  
     inet6 ::1 prefixlen 128  
     inet6 fe80::1%lo0 prefixlen 64 scopeid 0x2  
     groups: lo  
     nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>  
 root@kuna:~ #

We can double check that, kernel modules if_rtwn_usb and rtwn are loaded ...

 root@kuna:~ # kldstat | grep rtwn  
  4  1 0xffffffff82828000   dff7 if_rtwn_usb.ko  
  5  1 0xffffffff82836000  19140 rtwn.ko  
 root@kuna:~ #

Wi-Fi device is also visible as USB device ugen0.3 ... it refers to a USB Generic device attached to USB controller 0 as device number 3.

 root@kuna:~ # usbconfig  
 ugen1.1: <Intel EHCI root HUB> at usbus1, cfg=0 md=HOST spd=HIGH (480Mbps) pwr=SAVE (0mA)  
 ugen0.1: <Intel XHCI root HUB> at usbus0, cfg=0 md=HOST spd=SUPER (5.0Gbps) pwr=SAVE (0mA)  
 ugen0.2: <QuietKey Keyboard Dell Computer Corp.> at usbus0, cfg=0 md=HOST spd=LOW (1.5Mbps) pwr=ON (100mA)  
 ugen1.2: <Integrated Rate Matching Hub Intel Corp.> at usbus1, cfg=0 md=HOST spd=HIGH (480Mbps) pwr=SAVE (0mA)  
 ugen0.3: <EW-7811Un 802.11n Wireless Adapter [Realtek RTL8188CUS] Edimax Technology Co., Ltd> at usbus0, cfg=0 md=HOST spd=HIGH (480Mbps) pwr=ON (500mA)  
 root@kuna:~ #

To be able to use wlan (Wi-Fi LAN) network interface, we have to create one. It can be done manualy from console by following command

 ifconfig wlan0 create wlandev rtwn0

but if we want to do it automatically during the boot process, we have to add following two lines to /etc/rc.conf

wlans_rtwn0="wlan0" # Equivalent to: ifconfig wlan0 create wlandev rtwn0
ifconfig_wlan0="WPA DHCP country CZ"

That's enough to have wlan0 network interface on top of parent interface rtwn0.

Wi-Fi Client Connection Manager

That's where wpa_supplicant come into play. WPA (Wi-Fi Protected Access) is a security protocol developed by the Wi-Fi Alliance to secure wireless networks. A supplicant is the client device or software that requests access to a secure network.

The role of wpa_supplicant is to manage Wi-Fi client connections in Unix-like operating systems including FreeBSD. In FreeBSD we do not use wpa_supplicant directly, but it is used indirectly through /etc/rc.d/netif, which is a FreeBSD rc startup script responsible for configuring network interfaces during system boot or when manually invoked.

The only what we have to do is to create config file /etc/wpa_supplicant.conf with following content ...

network={
    ssid="YourSSID"
    psk="Your PreShared Key in correct format"
}

It is worth to mention, that WPA PreShared Key must be generated by the command wpa_passphrase and generated PSK has to be used in /etc/wpa_supplicant.conf

  root@kuna:/etc # wpa_passphrase PASNET YourPassword   
  network={   
    ssid="PASNET"   
    #psk="YourPassword"   
    psk=cce6e5a21451d52d430935b7ac315278f8c37b40cf453ac98b3f252c0faadde1   
  }   
  root@kuna:/etc #

If we have wlan0 interface configured in /etc/rc.conf as discussed above ...

ifconfig_wlan0="WPA DHCP country CZ"

... your system will try to connect to Wi-Fi network automatically during the boot.

If you do not want connect to Wi-Fi automatically, you have to add NOAUTO option to ifconfig_wlan0 config line in /etc/rc.conf configuration file

ifconfig_wlan0="WPA DHCP NOAUTO country CZ"

With the NOAUTO option enabled, you must manually bring up the wlan0 interface to connect to the configured Wi-Fi network.

 service netif start wlan0

and when wlan0 interface is up and associated, you can initiate DHCP Client (dhclient) ask your DHCP Server for network information like IP settings, default route, DNS, etc.

 service dhclient restart wlan0

To disconnect from Wi-Fi Access Point use following command 

 service netif stop wlan0

We are done. 
 
Your Wi-Fi should be working in FreeBSD. If not, the next section has some commands that might help you figure out what's wrong.
 

FreeBSD Wi-Fi Related Useful Commands

sysctl

General sysctl command can show us recognized Wi-Fi (wlan) devices.
 
 root@kuna:~ # sysctl net.wlan.devices  
 net.wlan.devices: rtwn0  
 root@kuna:~ #

ifconfig

Old good ifconfig can be used to manage Wi-Fi from console. 

Wi-Fi interface (fro exaple wlan0) is always created (aka cloned) on top of parent interface (rtwn0) in our case. /etc/rc.conf should be configures to create such wlan0 interface during the boot process, but sometime is good to know how to create wlan0 manually.

Let's create wlan0 interface 

 ifconfig wlan0 create wlandev rtwn0 wlanmode sta  
 ifconfig wlan0 up

We can also delete wlan0 interface if needed

 ifconfig wlan0 destroy

We can scan available SSIDs. 

ifconfig wlan0 list scan

 root@kuna:~ # ifconfig wlan0 list scan  
 SSID/MESH ID           BSSID             CHAN RATE    S:N   INT CAPS  
 PASNET.IoT            84:16:f9:b7:02:4a  11    54M -89:-95  100 EPS RSN HTCAP WME  
 PASNET                f0:21:e0:9d:e3:c6   6    54M -73:-95  100 EPS RSN BSSLOAD HTCAP VHTCAP VHTOPMODE VHTPWRENV WME  
 PASNET                f0:21:e0:e6:d2:d4   6    54M -91:-95  100 EPS RSN BSSLOAD HTCAP VHTCAP VHTOPMODE VHTPWRENV WME  
 46b272                f0:21:e0:9d:e3:c4   6    54M -73:-95  100 P  RSN HTCAP MESHCONF VHTCAP VHTOPMODE  
                       f0:21:e0:9d:e3:c8   6    54M -74:-95  100 ES  HTCAP VHTCAP VHTOPMODE VHTPWRENV WME  
 PASNET                f0:21:e0:e5:f3:84   6    54M -91:-95  100 EPS RSN BSSLOAD HTCAP VHTCAP VHTOPMODE VHTPWRENV WME  
 root@kuna:~ #

We can see three PASNET Access Points, because I have Wi-Fi Mesh with 3 APs.
The best signal I have is -73 dB with noice -95 dB.
 
Here’s what the numbers mean:
  • Signal = -73 dBm → This is the strength of the WiFi signal received. Lower absolute values (closer to 0) mean stronger signal. For example, -50 dBm is excellent, -85 dBm is quite weak.
  • Noise = -95 dBm → This is the background noise level. Lower is better here too, since it means less interference.
Signal-to-Noise Ratio (SNR)

SNR = Signal - Noise
SNR = (-73) - (-95) = 22 dB
 
What does 22 dB SNR mean?
  • 0–10 dB → Very poor. Connection may be unreliable or very slow.
  • 10–20 dB → Poor. Some basic connectivity, but likely packet loss or low speeds.
  • 20–40 dB → Fair to good. Usable for web browsing or video streaming.
  • 40+ dB → Excellent. Strong, reliable connection.
So 22 dB SNR is in Fair range. 
 
My FreeBSD Wi-Fi client is located just about 2 meters from the Wi-Fi access point. Since the USB Wi-Fi dongle lacks an external antenna, there’s little I can do to improve the signal strength and SNR.
 
In next chapter, I will focus on network performance, so we will see what throughput we can achieve.
 
We can list Wi-Fi regdomains (Regulatory Domains) 
 
What is Wi-Fi Regulatory Domain? A regdomain (regulatory domain) refers to a set of country-specific radio frequency regulations that control how wireless devices, especially Wi-Fi, can operate. Different countries allow different frequencies (channels), transmit power limits, bandwidth and radar avoidance rules (DFS - Dynamic Frequency Selection). For example, channel 12 and 13 are allowed in Europe, but often disabled in the US.
 root@kuna:/etc # ifconfig wlan0 list regdomain  
 :regdomain FCC country US anywhere -ecm  
 Channel  1 : 2412   MHz 11b        Channel  6 : 2437   MHz 11g ht/20  
 Channel  1 : 2412   MHz 11g        Channel  7 : 2442   MHz 11b  
 Channel  1 : 2412   MHz 11g ht/20  Channel  7 : 2442   MHz 11g  
 Channel  2 : 2417   MHz 11b        Channel  7 : 2442   MHz 11g ht/20  
 Channel  2 : 2417   MHz 11g        Channel  8 : 2447   MHz 11b  
 Channel  2 : 2417   MHz 11g ht/20  Channel  8 : 2447   MHz 11g  
 Channel  3 : 2422   MHz 11b        Channel  8 : 2447   MHz 11g ht/20  
 Channel  3 : 2422   MHz 11g        Channel  9 : 2452   MHz 11b  
 Channel  3 : 2422   MHz 11g ht/20  Channel  9 : 2452   MHz 11g  
 Channel  4 : 2427   MHz 11b        Channel  9 : 2452   MHz 11g ht/20  
 Channel  4 : 2427   MHz 11g        Channel 10 : 2457   MHz 11b  
 Channel  4 : 2427   MHz 11g ht/20  Channel 10 : 2457   MHz 11g  
 Channel  5 : 2432   MHz 11b        Channel 10 : 2457   MHz 11g ht/20  
 Channel  5 : 2432   MHz 11g        Channel 11 : 2462   MHz 11b  
 Channel  5 : 2432   MHz 11g ht/20  Channel 11 : 2462   MHz 11g  
 Channel  6 : 2437   MHz 11b        Channel 11 : 2462   MHz 11g ht/20  
 Channel  6 : 2437   MHz 11g  
 root@kuna:/etc #
We can set country to appropriate value.
 root@kuna:/etc # ifconfig wlan0 country CZ  
 root@kuna:/etc #
and check regdomain again if the change was applied.
 root@kuna:/etc # ifconfig wlan0 list regdomain  
 :regdomain ETSI country CZ anywhere -ecm  
 Channel  1 : 2412   MHz 11b        Channel  6 : 2437   MHz 11g ht/20  
 Channel  1 : 2412   MHz 11g        Channel  7 : 2442   MHz 11b  
 Channel  1 : 2412   MHz 11g ht/20  Channel  7 : 2442   MHz 11g  
 Channel  2 : 2417   MHz 11b        Channel  7 : 2442   MHz 11g ht/20  
 Channel  2 : 2417   MHz 11g        Channel  8 : 2447   MHz 11b  
 Channel  2 : 2417   MHz 11g ht/20  Channel  8 : 2447   MHz 11g  
 Channel  3 : 2422   MHz 11b        Channel  8 : 2447   MHz 11g ht/20  
 Channel  3 : 2422   MHz 11g        Channel  9 : 2452   MHz 11b  
 Channel  3 : 2422   MHz 11g ht/20  Channel  9 : 2452   MHz 11g  
 Channel  4 : 2427   MHz 11b        Channel  9 : 2452   MHz 11g ht/20  
 Channel  4 : 2427   MHz 11g        Channel 10 : 2457   MHz 11b  
 Channel  4 : 2427   MHz 11g ht/20  Channel 10 : 2457   MHz 11g  
 Channel  5 : 2432   MHz 11b        Channel 10 : 2457   MHz 11g ht/20  
 Channel  5 : 2432   MHz 11g        Channel 11 : 2462   MHz 11b  
 Channel  5 : 2432   MHz 11g ht/20  Channel 11 : 2462   MHz 11g  
 Channel  6 : 2437   MHz 11b        Channel 11 : 2462   MHz 11g ht/20  
 Channel  6 : 2437   MHz 11g  
 root@kuna:/etc #
NOTE! regdomain (regulatory domain) should be set in /etc/rc.conf to have it set by default. This is how should look the entry in /etc/rc.conf
 
ifconfig_wlan0="WPA DHCP country CZ"

wpa_passphrase

We already discused this utility, but one again. This is very important utility to generate PSK (Pre-Shared Key) in correct format. It generate a 256-bit (32 bytes, 64 hex digits) pre-shared WPA key from an ASCII passphrase you typically have set on your Access Point.
 root@kuna:/etc # wpa_passphrase PASNET YourPassword  
 network={  
     ssid="PASNET"  
     #psk="YourPassword"  
     psk=cce6e5a21451d52d430935b7ac315278f8c37b40cf453ac98b3f252c0faadde1  
 }  
 root@kuna:/etc #
NOTE! Such generated psk (Pre-Shared Key) must be added into your /etc/wpa_supplicant.conf config file and not the PreSharedKey in ASCII format, you typically know. 

NOTE! Generated (Pre-Share Key) is dependent on SSID, therefore even you have the same ASCII passphrase for SSID PASNET-A and SSID PASNET-B, the generated psk is different for PASNET-A and PASNET-B.

wpa_supplicant

The wpa_supplicant utility is an implementation of the WPA Supplicant component, i.e., the part that runs in the client stations. It implements WPA key negotiation with a WPA Authenticator and EAP authentication with an Authentication Server.  In addition, wpa_supplicant controls the roaming and IEEE 802.11 authentication/association support of the wlan(4) module and can be used to configure static WEP keys based on identified networks.

When we do Wi-Fi troubleshooting, we can try manual association and observe verbose output (that's what option -d does).
 wpa_supplicant -i wlan0 -c /etc/wpa_supplicant.conf -d

wifimgr

If you have Graphical Desktop Environment you can install wifimgr. It is a graphical (GUI) tool built using the Qt toolkit for managing wireless networks on FreeBSD.

pkg install -y wifimgr

However, WiFiMgr is a separate topic that I may cover in a future post when discussing FreeBSD-based desktop environments.

Network Performance

As FreeBSD Wi-Fi Client is connected to my Acces Point, we can check network details of wlan0 interface with following comamnd. 

 root@kuna:~ # ifconfig wlan0  
 wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500  
     options=0  
     ether 74:da:38:d3:86:80  
     inet 10.0.4.200 netmask 0xfffffc00 broadcast 10.0.7.255  
     groups: wlan  
     ssid PASNET channel 6 (2437 MHz 11g ht/20) bssid f0:21:e0:9d:e3:c6  
     regdomain ETSI country CZ authmode WPA2/802.11i privacy ON  
     deftxkey UNDEF AES-CCM 2:128-bit txpower 30 bmiss 7 scanvalid 60  
     protmode CTS ht20 ampdulimit 64k shortgi -stbc -ldpc -uapsd wme  
     roaming MANUAL  
     parent interface: rtwn0  
     media: IEEE 802.11 Wireless Ethernet MCS mode 11ng  
     status: associated  
     nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>

We can see that the Wi-Fi Client uses 2.4 GHz Frequency band and Wi-Fi Standard 802.11g (11g).

Standard: 802.11g
Frequency band: 2.4 GHz only
Max PHY rate: 54 Mbps (megabits per second)
Real-world speeds: Due to protocol overhead, interference, and environmental factors, actual throughput is typically around 20–25 Mbps.
 
Let's do some tests
  • iperf  
    • network upload throughput ~290 Kb/s (36 KB/s)
    • network download (-R) throughput ~7.84 Mb/s (980 KB/s)
  • iperf3 
    • network upload throughput ~261 Kb/s (32 KB/s)
    • network download (-R) throughput ~7.85 Mb/s (980 KB/s)
  • fetch 
    • download thtoughput ~7.7 Mb/s (960 KB/s)
  • speedtest (ookla) 
    • download throughput ~ 8.06 Mb/s (1 MB/s)

Conclusion

Download network performance is 8 Mb/s, which is far from perfect but relatively decent.
Upload network performance is between 250 and 300 Kb/s, which is horrible.

FreeBSD Wi-Fi support is often regarded as less robust compared to Linux, largely due to specific hardware and driver/firmware compatibility. For example, Realtek network adapters are generally not considered ideal for FreeBSD. Choosing the right Wi-Fi adapter is crucial, opt for models with strong FreeBSD driver support, such as those from Intel or Atheros, to ensure the best experience.

If time permits, I’ll conduct a similar test on Linux for comparison.

 

on

No comments:

Post a Comment

Subscribe to: Post Comments (Atom)