Question about Alfa AWUS036ACHM

[DerRheingold]

Hi,

I have a few problems with the Alfa AWUS036ACHM on my Raspi 4

Powered with a 4A power-brick the raspi and wifi start up fine. However I encounter two problems with this wifi-"stick" compared to the internal wifi.

• DHCP isn't working
• can't SSH-connect to Raspi

I want to use the Raspi as a routed (stand-alone) access point using this instruction: https://www.raspberrypi.com/documentation/computers/configuration.html#setting-up-a-routed-wireless-access-point
For testing I set everything up with the onboard-wifi (wlan0) and all is fine. Then I deactivated it in the /boot/config.txt, plugged in the Alfa-Wifi via the supplied USB-cable and restarted. The wifi-stick is mapped as wlan0, so all access-point-settings should account for this device too.

However I have a problem, that when I want to connect a device, DHCP doesn't hand out any addresses.
sudo systemctl status dnsmasq
returns a nice "warning: interface wlan0 does not currently exist"

Setting static IPs works fine and allows devices to connect. However it is impossible to SSH the Raspi with any device that is in the wifi. And again, this all works fine with the onboard-wifi and doesn't with the Alfa AWUS036ACHM. I'm clueless what to try. Any ideas?

Cheers :)

[morrownr]

Hi @DerRheingold

There is a lot to unpack here. Let me ask some questions so i can build a picture of the system you have:

Computer = Raspberry Pi 4B ?
OS = Raspberry Pi OS ? (what is the date of the iso? is it 32 bit or 64 bit?)

Regards

[DerRheingold]

Raspberry Pi 4 Model B Rev 1.4
Raspian Bullseye 32 bit

cat /etc/os-release says:

PRETTY_NAME="Raspbian GNU/Linux 11 (bullseye)"
NAME="Raspbian GNU/Linux"
VERSION_ID="11"
VERSION="11 (bullseye)"
VERSION_CODENAME=bullseye
ID=raspbian
ID_LIKE=debian
HOME_URL="http://www.raspbian.org/"
SUPPORT_URL="http://www.raspbian.org/RaspbianForums"
BUG_REPORT_URL="http://www.raspbian.org/RaspbianBugs"

[morrownr]

Okay. Thanks for the info.

The Jan 22 - 32 bit version of RasPiOS is best for now and that appears to be what you have.

Suggestions:

Remember that the ACHM is a USB2 adapter so I recommend making sure it is plugged into a USB2 port.

I have learned that it is best to turn off the internal wifi before you do anything with wifi. I understand and agree with your logic that it should work but there are many moving parts here so logic may not work.

The complexity of this project is such that it could take a lot of messages for us to make progress. I am going to recommend you start with a clean sd and follow my guide below:

https://github.com/morrownr/7612u/blob/main/AP_Mode-Bridged_Wireless_Access_Point.md

I understand that this is a Bridged guide and not a Routed guide but if you have the capability to set my guide up and optimize it, then we can work on adding the routing capability. My guide is heavily tested and works very well. It also contains a lot of information that the other guide does not.

Regards

[DerRheingold]

Thanks for getting back to me. I'm happy to confirm, that your instructions work perfectly 😁🥳

As I need the Raspi to work as a routed Access-point what steps are required to do so? I followed this instruction in the past with limited success: https://www.raspberrypi.com/documentation/computers/configuration.html#setting-up-a-routed-wireless-access-point

Do you have any advice/experience what I need to get from your instruction to a routed Access-point with DHCP running?
Working in bridged mode is not required but wouldn't hurt either :)

PS: following the instructions here I couldn't get the LED on the wifi-adapter to light up in any way 🤷‍♂️ Only a wifi-scan revealed it's working 😁

//EDIT:
This is what I tried, thought looked promising but when rebooting without ethernet attached, DHCP isn't working. When connecting to the WiFi with a static IP set I can't ssh to the Pi. I can only ssh to the Pi when it's connected to ethernet.

What I did was modified the /etc/dhcpcd.conf as follows:

denyinterfaces e* wl*
interface br0
static ip_address=192.168.178.79/24 # Static IP for ethernet

interface wlx00c0caae65b1
static ip_address=192.168.1.1/24 #Static IP for the Wifi-Gateway
nohook wpa_supplicant

The /etc/dnsmasq.conf is now with this:

interface=wlx00c0caae65b1
bind-dynamic
bogus-priv
dhcp-range=192.168.1.100,192.168.1.200,255.255.255.0,24h
dhcp-option=option:dns-server,192.168.1.1

no-dhcp-interface=eth0

The /etc/hostapd/hostapd-2g.conf is unchanged from after your tutorial where all worked. However when doing a sudo hostapd -dd /etc/hostapd/hostapd-2g.conf this is returned (and the hotspot is up and running):

random: getrandom() support available
Configuration file: /etc/hostapd/hostapd-2g.conf
nl80211: TDLS supported
nl80211: TDLS external setup
nl80211: Supported cipher 00-0f-ac:1
nl80211: Supported cipher 00-0f-ac:5
nl80211: Supported cipher 00-0f-ac:2
nl80211: Supported cipher 00-0f-ac:4
nl80211: Supported cipher 00-0f-ac:10
nl80211: Supported cipher 00-0f-ac:8
nl80211: Supported cipher 00-0f-ac:9
nl80211: Supported cipher 00-0f-ac:6
nl80211: Supported cipher 00-0f-ac:13
nl80211: Supported cipher 00-0f-ac:11
nl80211: Supported cipher 00-0f-ac:12
nl80211: Using driver-based off-channel TX
nl80211: Driver-advertised extended capabilities (default) - hexdump(len=8): 00 00 00 00 00 00 00 40
nl80211: Driver-advertised extended capabilities mask (default) - hexdump(len=8): 00 00 00 00 00 00 00 40
nl80211: Use separate P2P group interface (driver advertised support)
nl80211: interface wlx00c0caae65b1 in phy phy0
nl80211: Set mode ifindex 4 iftype 3 (AP)
nl80211: Setup AP(wlx00c0caae65b1) - device_ap_sme=0 use_monitor=0
nl80211: Subscribe to mgmt frames with AP handle 0x1c8dfc8
nl80211: Register frame type=0xb0 (WLAN_FC_STYPE_AUTH) nl_handle=0x1c8dfc8 match=
nl80211: kernel reports: Match already configured
nl80211: Register frame command failed (type=176): ret=-114 (Operation already in progress)
nl80211: Register frame match - hexdump(len=0): [NULL]
nl80211: Could not configure driver mode
nl80211: deinit ifname=wlx00c0caae65b1 disabled_11b_rates=0
nl80211: Remove monitor interface: refcount=0
nl80211: Remove beacon (ifindex=4)
netlink: Operstate: ifindex=4 linkmode=0 (kernel-control), operstate=6 (IF_OPER_UP)
nl80211 driver initialization failed.
hostapd_interface_deinit_free(0x1c8b050)
hostapd_interface_deinit_free: num_bss=1 conf->num_bss=1
hostapd_interface_deinit(0x1c8b050)
wlx00c0caae65b1: interface state UNINITIALIZED->DISABLED
hostapd_bss_deinit: deinit bss wlx00c0caae65b1
wlx00c0caae65b1: AP-DISABLED
hostapd_cleanup(hapd=0x1c8bed0 (wlx00c0caae65b1))
wlx00c0caae65b1: CTRL-EVENT-TERMINATING
hostapd_free_hapd_data: Interface wlx00c0caae65b1 wasn't started
hostapd_interface_deinit_free: driver=(nil) drv_priv=(nil) -> hapd_deinit
hostapd_interface_free(0x1c8b050)
hostapd_interface_free: free hapd 0x1c8bed0
hostapd_cleanup_iface(0x1c8b050)
hostapd_cleanup_iface_partial(0x1c8b050)
hostapd_cleanup_iface: free iface=0x1c8b050

and sudo systemctl status dnsmasq thows two warnings:

Mar 30 05:49:52 raspberrypi dnsmasq[538]: warning: interface wlx00c0caae65b1 does not currently exist
Mar 30 05:49:53 raspberrypi dnsmasq[538]: no servers found in /run/dnsmasq/resolv.conf, will retry

and ifconfig returns this:

br0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.178.79 netmask 255.255.255.0 broadcast 192.168.178.255
inet6 2001:9e8:2e5b:7c00:a7d6:c002:36e6:136c prefixlen 64 scopeid 0x0
inet6 fe80::80f9:eea6:4896:eabb prefixlen 64 scopeid 0x20
ether 26:a9:18:d1:92:ae txqueuelen 1000 (Ethernet)
RX packets 5410 bytes 936411 (914.4 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 869 bytes 160084 (156.3 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
ether e4:5f:01:76:5f:75 txqueuelen 1000 (Ethernet)
RX packets 101392 bytes 120481134 (114.8 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 19091 bytes 2547666 (2.4 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10
loop txqueuelen 1000 (Local Loopback)
RX packets 21 bytes 2403 (2.3 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 21 bytes 2403 (2.3 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

wlx00c0caae65b1: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet6 fe80::2c0:caff:feae:65b1 prefixlen 64 scopeid 0x20
ether 00:c0:ca:ae:65:b1 txqueuelen 1000 (Ethernet)
RX packets 18220 bytes 2387729 (2.2 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 97932 bytes 121873236 (116.2 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

So you can imagine that I have some questions and many more WTFs flying around in my mind because of the errors returned and things not working as intended.

[morrownr]

Hi @DerRheingold

I'm happy to confirm, that your instructions work perfectly

Good.

I'm am sorry for being slow to respond but it can take me some time to respond as I am busy.

I'm glad the bridged guide installed and worked. I had asked you to do that partly for educational purposes and party to make sure your hardware is setup okay. I actually did not intend for you to modify that installation as the needed changes are many and can be somewhat confusing.

What I actually recommend for people like you that want a routed setup is for you to use openWRT:

https://openwrt.org/toh/raspberry_pi_foundation/raspberry_pi

openWRT is just another Linux distro just like Raspberry Pi OS is a Linux distro. The big difference is that the Raspberry Pi OS is a general purpose OS whereas openWRT is a specific purpose OS... and it is very good and is designed to do exactly what you asking to do.

openWRT has the driver for the mt7610u chipset that is used in the Alfa ACHM. It will not be installed in the iso that you install but it is simple to install. The package name is kmod-mt76x0u.

I have used my ACHM with openWRT a lot and it works well. What you might do is use the internal wifi for one band and the ACHM for the other band so that you have a dual band router.

Warning: There are many guides on the internet for setting up openWRT on a RasPi4B. Many of those guides are old so you should only use very recent guides that support installing openWRT 21.02.

This can also be a learning experience so if you find something you do not understand, you can ask here or in the openWRT forums.

Regards

[DerRheingold]

Thanks for pointing me towards OpenWRT :) Took me some time, but eventually got it up and running. For anyone else looking here, this video helped me a lot: https://www.youtube.com/watch?v=jlHWnKVpygw)

Now the challenge is to get Nginx with RTMP up and running on the OpenRwt Raspi. Unfortunately not too much documentation on the web for that :-/

[morrownr]

Now the challenge is to get Nginx with RTMP up and running on the OpenRwt Raspi. Unfortunately not too much documentation on the web for that :-/

Did you about it in the OpenWRT forums?