ESP32: Static IP address as STA, DHCP stop - how to bite?

Question

Good morning! I have a bit of a problem with esp32. Namely, I would like to connect to the router as STA, but get a static IP address, not assigned by DHCP. The problem will arise in that I found a function to stop the DHCP server whose header looks like this: . Seemingly everything looks ok,...

khoam · Accepted Answer

. This function does not stop the DHCP server, but the DHCP client as long as it was previously enabled. . It depends which version of this function. It is implemented in the file esp_netif_lwip.c : Code: C / C++Log in, to see the code . The code you have provided comes from the file esp_netif_loopback.c Example initialisation in STA mode with static address: Code: C / C++Log in, to see the code . . So version 4.3?

krzbor · Accepted Answer

The address is either static (that is, you assign it yourself in code) or dynamic assigned by DHCP. If you want a static address, why don't you enter it in the program code (obviously an address outside the DHCP pool) ?

khoam · Accepted Answer

. So that there is no potential conflict with another network device operating on the same IP subnet that would take the address via DHCP.

ex-or · Accepted Answer

From a network management point of view, a better option is to leave the DHCP clint and configure the server to always assign the same address to the device. An even better option IMHO is local DNS and using the device name. Not all fucked up routers have this. This is by the way.

miszczo997 · Answer

. Yes, a mental abbreviation, of course I meant retrieving the address from the DHCP server. . Exactly from that file. This is how VSCode directed me. . Thank you, I am getting on with the testing. . Here I cheated, I thought the espressif plugin for VSCode was downloading the latest version. However, I have v4.2.1. Code: text Expand Select all Copy to clipboardmiszczo@DESKTOP-0D19UAR MINGW64 /c/uC/ESP32/esp-idf ((v4.2.1)) $ git describe v4.2.1 . . I do this, only ESP kept getting me the address assigned by DHCP anyway, even when I called the function esp_netif_dhcps_stop(netif); and then I typed it in manually. Btw, why does the address have to be from outside the DHCP address pool?

khoam · Answer

. In ESP you can run the mDNS service and broadcast your own name to the network.

miszczo997 · Answer

Right, I hadn't thought of that. That's for sure, worse as there is no access to the router configuration. Here I want to use two ESP32s that will connect to each other through the router and transmit audio. I'm not connecting them directly to each other because I want to be able to access their configuration from the network via an http server(I want to be able to configure them from the PC via eth cable). The example given by khoam works as expected. Thank you all for your help. I leave the topic open for a few days should anyone have anything else to add. Greetings

Anonymous · Answer

. You can't make an IP reservation on the router for this mac addres ?

miszczo997 · Answer

I'm assuming the scenario that the only data I get when connecting to the router is the bssid and network password.

Anonymous · Answer

. If I understand you correctly, you can then NOT give a static IP because you don't know the DHCP range the server is using. Sooner or later there will be an IP conflict and you will put the network to bed. That's what DHCP is for (it manages IP addresses) so that there is no conflict. [edit] If you only get the SSID and password how will you know what the address is and what address to assign, what mask and what gateway ?

khoam · Answer

If the mDNS service is initiated on both ESP32s, the question of how the IP address is assigned to the ESP32 is a secondary matter - it is important that it matches the IP subnet address managed by the AP router. There is also no need for a local DNS server on the IP subnet or additional configuration of the AP router. ESP32 devices can only 'detect' each other based on established names. On the other hand, detection and access to the ESP32 from a PC station can be done via Bonjour (Windows) or Zeroconf (Linux), also based on ESP32 names. It also does not matter whether the ESP32 is operating in STA mode, AP mode or both.

miszczo997 · Answer

I will check with a computer connected to the same network. I just don't know about the address pool, but if DHCP assigns a specific address with a given mask, isn't it enough to just assign an address for the ESP from outside the address pool defined by the mask? Here, I'm not sure what will happen if there are several independent subnets defined in the router - most likely it will all get out of whack anyway. . This will probably be the best approach though. I need to look into this more thoroughly as I was not previously aware of such a service.

Anonymous · Answer

. The mask relates to the network - not the address pool distributed by DHCP. However, it is needed for the correct configuration of a network address. IP alone is not enough.

miszczo997 · Answer

Final working wifi startup procedure based on the instructions given by @khoam Code: C / C++Log in, to see the code .

[Solved] ESP32: Static IP address as STA, DHCP stop - how to bite?

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