I've been trying to set up RPi to act as both a wireless AP and wifi station simultaneously. I've got nothing but errors and bugs so far. I did however find this guide that creates a virtual AP and runs a station on the same card which im okay with (instead of using 2 seperate wifi cards)

Link to guide: https://imti.co/iot-wifi/

I followed the steps and everything seems to connect, the only problem is I am not receiving an internet connection on the device that connects to the AP of the RPi. I have made sure that the Pi does have acces to internet when its connected to the external network. The aim of my project is to connect the user to the internet through it to the outside network.

Any suggestions?

  • Ah, let me see. So you have followed the IMTI's instructions and find everything OK (using only one wifi card). The problem arises only when you start using 2 separate wifi cards. I have two questions: (1) Does IMIT allow you to use 2 wifi cards? (2) If IMIT does not say if two cards are allowed. Did you make any changes to the IMTI's instructions to cater for two cards?
    – tlfong01
    Jun 23, 2019 at 8:46
  • 1
    Any question which boils down to "I followed a tutorial and it doesn't work" means either you didn't follow the tutorial or it doesn't work.
    – Milliways
    Jun 23, 2019 at 8:50
  • @user105104, I browsed IMIT's documents and found them very impressive. I have no experience in the Docker thing. I am going to learn it, and only afterwards I can be confident to try to reproduce your situation. There are other things you may like to let us know, say what is your stretch version? wifi card spec?
    – tlfong01
    Jun 23, 2019 at 9:14
  • There seems some confusion. I thought I saw your answer but no longer found it. You seemed to have mentioned two network cards and I commented, but all disappeared. Anyway, I tried again. I do sometimes use two "network cards". Actually one is the wift controller built into Rpi3. Another card is actually a USB wifi dongle inserted into the Rpi's USB socket. If I remember correctly, Raspbian will automatically switch to the USB wifi dongle. In other words, you CANNOT use two "network cards" (one built in, the other USB Wifi dongle) at the same time. But I am still a newbiei, so not sure.
    – tlfong01
    Jun 23, 2019 at 13:53
  • @tlfong01, yeah the comments seem to be removed. I don't mind using only one WiFi card. My main problem is that I am not getting internet access on any device I cannot with to the raspberry pi Jun 23, 2019 at 14:04

1 Answer 1



Rpi3B+ Stretch9 WiFi Station + AP IOT Hotspot Docker Setting Up Problem

Short Answer

1. WiFi Station + AP IOT Hotspot Based Config API Setup Notes V1.0

Now I am doing the first step of setting up - Installing the docker. This setup step is summarized in Appendix H below.

Update 2019jun25hkt2104

Docker Hello World running OK, though I don't know what is going on. Need to google again before moving on.

iot wifi

/ to continue, ...

Long Answer


The OP's setup involving docker is a bit complicated. I need to do much research before I can duplicate his setup and tried to find the problem.

I have heard about the Docker thing for some time, but I have never tried it. Just now I skimmed the wikipedia and guess that it is sort light weight and therefore space/time/process efficient virtual machine thing like the very old guy System 360 VM. Microsoft also has similar light virtualization stuff. Perhaps I start learning by doing, sort of MIT style ...

One thing I don't understand is why the Wifi called "IOT WiFi". Anyway, I think I can start messing around without understanding everything. I am a huge fan of Oliver Heaviside. I always remember him saying the following:

Am I to refuse to eat because I do not fully understand the mechanism of digestion? - Heaviside

Research Notes

Engineering Experimentation Notes


  1. Rpi3 WiFi Station + AP IOT hotspot based configuration API – Craig Johnston 2018mar15

  2. About Craig Johnston

  3. Rpi3 As Wireless Client And Wireless AP – Raspberry Pi forum thread

  4. Tutorial on Setting up a Raspberry Pi as a WiFi access point – Adafruit

  5. How to connect to a WPA/WPA2 WiFi network using Linux command line – linuxcommando

  6. Automatically connect a Raspberry Pi to a Wifi network – weWorkWePlay

  7. Docker - Wikipedia

  8. Go - Wikipedia

  9. Virtualisation – Wikipedia

  10. WAP (Wireless Access Point) - Wikipedia

  11. Hotspot (Wi-Fi) - Wikipedia

12. Setting up a Raspberry Pi as an access point in a standalone network (NAT) - Rpi

13. cjimti iotwifi giihub

14. No Internet on AP - zeyadtarek 2019jun23

15. Wireless repeater - Wikipedia

16. Wireless (Network) Bridge - Wikipedia

17. Access point as WiFi router/repeater, optional with bridge


Appendix A - WiFi Station + AP IOT HotsSpot (Craig Johnston) Learning Notes

IOT Wifi is very small/8MB Docker Container built for the Raspberry Pi 3. IOT Wifi exposes a simple JSON based REST API for controlling the wireless network interface. This container allows the Raspberry Pi to accept wifi connections as an access point (aka AP) while at the same time connecting to an existing wifi network (station mode).

Go (Golang) was used to develop the main application code, to produce a minimal docker image with great performance. The container runs Alpine Linux with small, optimized versions of hostapd, wpa_supplicant and dnsmasq, controlled by the container’s API endpoints.

Appendix B - Docker - Wikipedia Learning Notes

Docker is a set of coupled software-as-a-service and platform-as-a-service products that use operating-system-level virtualization to develop and deliver software in packages called containers. The software that hosts the containers is called Docker Engine.

Containers are isolated from each other and bundle their own software, libraries and configuration files; they can communicate with each other through well-defined channels. All containers are run by a single operating-system kernel and are thus more lightweight than virtual machines. Containers are created from images that specify their precise contents.

Appendix C - Virtualization - Wikipedia Learning Notes

OS-level virtualization refers to an operating system paradigm in which the kernel allows the existence of multiple isolated user-space instances. Such instances, called containers ... may look like real computers from the point of view of programs running in them. A computer program running on an ordinary operating system can see all resources (connected devices, files and folders, network shares, CPU power, quantifiable hardware capabilities) of that computer. However, programs running inside of a container can only see the container's contents and devices assigned to the container.

On ordinary operating systems for personal computers [tlfong01 - Rpi included?], a computer program can see (even though it might not be able to access) all the system's resources. They include:

Hardware capabilities, such as the CPU and the network connection Data that can be read or written, such as files, folders and network shares Connected peripherals it can interact with, such as webcam, printer, scanner, or fax

With operating-system-virtualization, or containerization, it is possible to run programs within containers, to which only parts of these resources are allocated.

Appendix D - Go Wikipedia Learning Notes

Go, also known as Golang, is a statically typed, compiled programming language designed at Google. Go is syntactically similar to C, but with memory safety, garbage collection, structural typing, and CSP-style concurrency.

Go was designed at Google in 2007 to improve programming productivity in an era of multicore, networked machines and large codebases. The designers wanted to address criticism of other languages in use at Google, but keep their useful characteristics:

Static typing and run-time efficiency (like C++)

Readability and usability (like Python or JavaScript)

High-performance networking and multiprocessing

The designers were primarily motivated by their shared dislike of C++.

Go is influenced by C

Distinctive approaches to particular problems:

Built-in concurrency primitives: light-weight processes, channels, and the select statement.

An interface system in place of virtual inheritance, and type embedding instead of non-virtual inheritance.

A desire to keep the language specification simple enough to hold in a programmer's head, in part by omitting features which are common in similar languages.

Go's syntax includes changes from C aimed at keeping code concise and readable.

Go has a number of built-in types, ... Record types can be defined with the struct keyword.

Pointers are available for all types,

For a pair of types K, V, the type map[K]V is the type of hash tables mapping are built into the language

Go provides two features that replace class inheritance: embedding, which can be viewed as an automated form of composition or delegation, interfaces, which provides runtime polymorphism.

In Go's package system, each package has a path and a name

The Go language has built-in facilities, as well as library support, for writing concurrent programs. Concurrency refers not only to CPU parallelism, but also to asynchrony: letting slow operations like a database or network-read run while the program does other work, as is common in event-based servers.

Go's concurrency can be used to program shared memory multi-processor machines.

Appendix E - WAP (Wireless Access Point) - Wikipedia Learning Notes

In computer networking, a wireless access point (WAP), or more generally just access point (AP), is a networking hardware device that allows other Wi-Fi devices to connect to a wired network.

The AP usually connects to a router (via a wired network) as a standalone device, but it can also be an integral component of the router itself. An AP is differentiated from a hotspot, which is the physical location where Wi-Fi access to a WLAN is available.

An AP connects directly to a wired local area network, typically Ethernet, and the AP then provides wireless connections using wireless LAN technology, typically Wi-Fi, for other devices to use that wired connection. APs support the connection of multiple wireless devices through their one wired connection.

Wireless access point vs ad hoc network

Some people confuse wireless access points with wireless ad hoc networks. An ad hoc network uses a connection between two or more devices without using a wireless access point; The devices communicate directly when in range. Because setup is easy and does not require an access point, an ad hoc network is used in situations such as a quick data exchange or a multiplayer video game. Due to its peer-to-peer layout, ad hoc Wi-Fi connections are similar to connections available using Bluetooth.

Wireless networking lags wired networking in terms of increasing bandwidth and throughput. As of 2013, high-density 256-QAM (TurboQAM) modulation, 3-antenna wireless devices reach speeds 240 Mbit/s 13m, 360Mbit/s at 10m, 380 Mbit/s at 2m, or 20 to 25 Mbit/s at 2m line of sight (IEEE 802.11g), wired hardware of similar cost reaches closer to 1000 Mbit/s up to specified distance of 100 m with twisted-pair cabling in optimal conditions (Cat5 or better cabling with Gigabit Ethernet).

Appendix F - Hotspot (Wi-Fi) - Wikipedia Learning Notes

A hotspot is a physical location where people may obtain Internet access, typically using Wi-Fi technology, via a wireless local area network (WLAN) using a router connected to an internet service provider.

Public hotspots may be created by a business for use by customers, such as coffee shops or hotels. Public hotspots are typically created from wireless access points configured to provide Internet access, controlled to some degree by the venue. In its simplest form, venues that have broadband Internet access can create public wireless access by configuring an access point (AP), in conjunction with a router and connecting the AP to the Internet connection. A single wireless router combining these functions may suffice.

Private hotspots may be configured on a smartphone or tablet with a mobile network data plan to allow Internet access to other devices via Bluetooth pairing or if both the hotspot device and the device/s accessing it are connected to the same Wi-Fi network.

The public can use a laptop or other suitable portable device to access the wireless connection (usually Wi-Fi) provided. Of the estimated 150 million laptops, 14 million PDAs, and other emerging Wi-Fi devices sold per year for the last few years, most include the Wi-Fi feature.

Public hotspots are often found at airports, bookstores, coffee shops, department stores, fuel stations, hotels, hospitals, libraries, public pay phones, restaurants, RV parks and campgrounds, supermarkets, train stations, and other public places. Additionally, many schools and universities have wireless networks on their campuses.

Free hotspots operate in two ways: Using an open public network is the easiest way to create a free hotspot. All that is needed is a Wi-Fi router. Similarly, when users of private wireless routers turn off their authentication requirements, opening their connection, intentionally or not, they permit piggybacking (sharing) by anyone in range.

Closed public networks use a HotSpot Management System to control access to hotspots. This software runs on the router itself or an external computer allowing operators to authorize only specific users to access the Internet.

A commercial hotspot may feature a captive portal / login screen / splash page that users are redirected to for authentication and/or payment.

Software hotspots

Many Wi-Fi adapters built into or easily added to consumer computers and mobile devices include the functionality to operate as private or mobile hotspots, sometimes referred to as "mi-fi". The use of a private hotspot to enable other personal devices to access the WAN (usually but not always the Internet) is a form of bridging, and known as tethering.

Manufacturers and firmware creators can enable this functionality in Wi-Fi devices on many Wi-Fi devices, depending upon the capabilities of the hardware, and most modern consumer operating systems, including Android, Apple OS X 10.6 and later, Windows mobile, and Linux include features to support this. Additionally wireless chipset manufacturers such as Atheros, Broadcom, Intel and others, may add the capability for certain Wi-Fi NICs, usually used in a client role, to also be used for hotspot purposes. However, some service providers, such as AT&T, Sprint, and T-Mobile charge users for this service or prohibit and disconnect user connections if tethering is detected.

Third-party software vendors offer applications to allow users to operate their own hotspot, whether to access the Internet when on the go, share an existing connection, or extend the range of another hotspot.

Appendix G - Rpi3 WiFi Station + AP IOT Config API Learning Notes

IOT Wifi is very small/8MB Docker Container built for Rpi3. IOT Wifi exposes a simple JSON based REST API for controlling the wireless network interface. This container allows the Raspberry Pi to accept wifi connections as an access point (aka AP) while at the same time connecting to an existing wifi network (station mode).

> IOT Wifi sets up network interfaces, runs hostapd, wpa_supplicant and dnsmasq to run simultaneously, allowing a user (or another service) to connect to the Raspberry Pi via hostapd/dnsmasq and issue commands that configure and connect wpa_supplicant to another AP. IOT Wifi then exposes a small web server on the Pi and offers a JSON based REST API to configure Wifi. The IOT Wifi container allows you to build a custom Captive Portal web page or even programmatically connect from another device and use the exposed API to configure the target device.

Using wifi to configure a wifi connection is often a standard requirement for IOT. As Raspberry Pis are becoming a popular choice as an IOT platform, this helps solve the frequent need to manage AP and Station modes.

Appendix H Rpi3 WiFi Station + AP Setup notes

Disable wpa_supplicant on Raspberry Pi

You do not want the default wpa_supplicant (the software that communicates with the wifi driver and connects to Wifi networks,) running and competing with the IOT Wifi container.

  • prevent wpa_supplicant from starting on boot $ sudo systemctl mask wpa_supplicant.service

  • rename wpa_supplicant on the host to ensure that it is not # used. sudo mv /sbin/wpa_supplicant /sbin/no_wpa_supplicant

  • kill any running processes named wpa_supplicant $ sudo pkill wpa_supplicant

Install Docker on Raspberry Pi

Ssh into the Pi or use the terminal application from the desktop on the Pi to get a Bash shell.

Install Docker

  • add pi user to Docker user group $ sudo usermod -aG docker pi

Usermod Docker

Reboot the Pi and test Docker.

$ sudo reboot

After reboot, ensure Docker is installed correctly by running a Hello World Docker container.

  • run the Docker Hello World container and remove the container
  • when finished (the --rm flag)

Appendix I - Wireless Repeater - Wikipedia Learning Notes

A wireless repeater (also called wireless range extender) takes an existing signal from a wireless router or wireless access point and rebroadcasts it to create a second network. When two or more hosts have to be connected with one another over the IEEE 802.11 protocol and the distance is too long for a direct connection to be established, a wireless repeater is used to bridge the gap. It can be a specialized stand alone computer networking device. Also, some wireless network interface controllers (WNIC)s optionally support operating in such a mode. Those outside of the primary network will be able to connect through the new "repeated" network. However, as far as the original router or access point is concerned, only the repeater MAC is connected, making it necessary to enable safety features on the wireless repeater. Wireless repeaters are commonly used to improve signal range and strength within homes and small offices.

Uses - area has no wireless hotspot, area with much interference, computer between access point too great

Some wireless range extending devices connect via a USB port. These USB adapters add Wi-Fi capability to desktop PCs and other devices that have standard USB ports. USB supports not only the data transfers required for networking, but it also supplies a power source so that these adapters do not require electrical plugs.

Appendix J - Wireless Bridge - Wikipedia Learning Notes

A network bridge is a computer networking device that creates a single aggregate network from multiple communication networks or network segments. This function is called network bridging. Bridging is distinct from routing. Routing allows multiple networks to communicate independently and yet remain separate, whereas bridging connects two separate networks as if they were a single network.

In the OSI model, bridging is performed in the data link layer (layer 2).4 If one or more segments of the bridged network are wireless, the device is known as a wireless bridge.

/ to continue, ...



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