Configure Proper Policies for OUTPUT of iptables

There are two occasions in which a server sends outgoing packets: 1. The local host process proactively connects to an external server, for example, performing an HTTP access, or sending data to a log server. 2. The local host responds to the external access to the local services. If no policy is...

Configure the Default Policies of nftables to DROP Properly

For security purposes, the nftables base chains INPUT, OUTPUT, and FORWARD are similar to those of iptables. You need to configure the DROP policy for all packets, and then add the ACCEPT policy to the base chains to open related services and ports. If the base chains are not configured or the ho...