Linux › Section I · Your network and its configuration › Topic I.12
Firewalls
Every Linux kernel contains a packet filter that can accept, drop or reject traffic at several points on its way through the machine. This topic shows how that filter is organised, how to write rules for it with nftables and the older iptables, and how the friendlier ufw and firewalld front-ends fit on top.
In this topic
- Filtering inside the kernel
- Tables, chains and rules
- iptables, the classic tool
- Worked example: when order goes wrong
- nftables, the current framework
- Worked example: a default-deny host firewall
- Strategy: allow what you trust
- ufw on Ubuntu
- firewalld on Fedora and RHEL
- Common mistakes to avoid
- Key takeaways
This topic is part of Wuanberri Pro. Checking your access…