Linux router firewall configuration with NetworkManager and firewalld

Linux router firewall configuration with NetworkManager and firewalld

Introduction I use Linux as an Internet router. I use it with multiple rules (rather simple) using a very simple baseline configuration. The router has two main network interfaces – one facing the internal LAN, and one facing the external fibre connection, where it needs to use a specific VLAN, and then – use PPPoE…

Linux answers to ARP who-is on the wrong network interface

Assume a server has two network interfaces as follows: eth0 : 192.168.0.1/24 eth1 : 192.168.10.1/24 Let’s assume these interfaces reside on the different VLANs. Lets assume they were connected incorrectly, in such a way that eth0 is connected to VLAN 10, which servers 192.168.10.0/24 and eth1 is connected to VLAN 2, which serves 192.168.0.0/24. You…