As usual, long story short: I’ve to setup a firewall to log traffic, block some stuff and do some other things. – epel repo is required – The system is made of a single CentOS machine with 2 physical network adapters: eth0, connected to WAN, static IP address 192.168.0.3 eth1, connected to LAN, static IP address 10.0.0.1/24 .:. Network adapters configuration WAN network adapter: [root@CentOS ~]# vi /etc/sysconfig/network-scripts/ifcfg-eth0 DEVICE="eth0" BOOTPROTO="none" HWADDR="**:**:**:**:**:**" IPADDR=192.168.0.3 NETMASK=255.255.255.0 GATEWAY=192.168.0.1 DNS=192.168.0.1 IPV6INIT="yes" IPV6_AUTOCONF="yes" NM_CONTROLLED="yes" ONBOOT="yes" TYPE="Ethernet" UUID="***" LAN network adapter: …