Wei Guo

In some industrial or legacy network environments, certain devices (like QNX systems) require traffic to be tagged with specific VLANs. Docker containers, by default, do not send VLAN-tagged traffic directly. This article explains the principle behind and introduces how to solve this problem.

This technical document provides a step-by-step guide to troubleshoot and resolve issues where an external network cannot communicate with Docker containers, particularly for UDP traffic. Background # When using docker-compose to start a group of containers with a custom bridge network (e.g., test-network), you might encounter issues where UDP packets are not transmitted correctly between containers or between containers and external services. By analyzing iptables, nftables, and container listening states, you can configure the containers to properly listen and respond to UDP packets on specific ports.

What is security policy? # Official documents: https://www.qnx.com/developers/docs/7.1/index.html#com.qnx.doc.security.system/topic/manual/security_policies.html It basically is a file that in a system level set processes which operations it is permitted to do.