search

esp8266 / Arduino

ESP8266 core for Arduino
GNU Lesser General Public License v2.1
16k stars 13.33k forks source link

DHCP Transaction Id not random #3773

Closed ghost closed 6 years ago

ghost commented 6 years ago

----------------------------- Remove above -----------------------------

Basic Infos

Hardware

Hardware: ESP-12E Core Version: 2.4.0-rc1

Description

The DHCP Transaction Id generated by the ESP8266es does not seem to be random - as required by rfc2131. That generates strange connection issues when multiple ESP8266es are speaking with the same DHCP Server. The ESP seems always to start with the transaction ID 0xabcd0001 - and only later seems to be counting up the ID. The correct behaviour would be always to use random Ids - or at least as the initial value.

Depending on the implementation. the server may ignore the dhcp request (because for the server, the transaction may be in another state and the request may be invalid).

For the ESP users, this shows as stange connection/reonnection issues.

devyte commented 6 years ago

@TylerDurden23 do you have a wireshark dump or something else that shows this? Does #3362 help?

ghost commented 6 years ago

image

devyte commented 6 years ago

@TylerDurden23 lwip2 is now merged, it can be selected from the Arduino IDE menu. Does using it help?

ghost commented 6 years ago

Is this version available via Boardmanager?

devyte commented 6 years ago

You have to uninstall any version you have installed via boardmanager, and install git (instructions are on readthedocs). Then restart the Arduino IDE, and you should see the option for lwip in the menu. Be aware that the ESPAsync libs don't yet build with lwip2, in case you're using them.

ghost commented 6 years ago

@devyte The DHCP request id Looks random now - my project uses the pubsub library - that does not seem to work (async issue most likely).

Regards.

devyte commented 6 years ago

Given that the original issue seems fixed with lwip2, I'm closing. I understand that pubsub is a 3rd party lib. If it shows a problem, please open a new issue, and fill in the fields. Please be aware that in that case the problem should be narrowed down to relevant code in this repo, so most likely you will need help from pubsub's author first.