Docker 28.0 forwarding traffic

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Docker version 28.0 implemented some security changes on Linux machines that strengthen the iptables forwarding rules.
If you notice that you have connectivity issues related to forwarding, you might need to re-enable permissive forwarding.

Here are 2 solutions :

Modify daemon.json

sudo vim /etc/docker/daemon.json

{
  "ip-forward-no-drop": true
}

sudo systemctl restart docker

Create a network with nat-unprotected

docker network create --subnet=10.3.192.0/23 --opt com.docker.network.bridge.gateway_mode_ipv4=nat-unprotected mynet46

Sources :

https://www.docker.com/blog/docker-engine-28-hardening-container-networking-by-default/

Création de l'article : 13/04/2025, Auteur : Informaticien Guyane