iptables Rules Not Persisting After Reboot — Firewall Configuration Lost

Fix iptables firewall rules disappearing after system reboot because rules are stored in memory and not saved to persistent configuration files. This guide covers everything you need to know about this topic, including common causes, step-by-step solutions, and answers to frequently asked questions.

Here are the key things to understand: iptables rules are stored in kernel memory and are lost when the system reboots. Rules must be explicitly saved to a file and restored on boot to persist. Different distributions use different persistence methods: iptables-persistent (Debian/Ubuntu), iptables-services (RHEL/CentOS). nftables is the successor to iptables on modern Linux distributions. Docker, Kubernetes, and other container runtimes add their own iptables rules dynamically. Understanding these fundamentals will help you diagnose and resolve this issue more effectively.

The most common reasons this occurs include: iptables-persistent or iptables-services package not installed. Rules saved with iptables-save but not configured to restore on boot. Firewalld or ufw overriding iptables rules on startup. Docker or Kubernetes resetting iptables chains on container runtime restart. Identifying the root cause is the first step toward finding the right solution.

To resolve this, follow these recommended steps: Debian/Ubuntu: install iptables-persistent: apt install iptables-persistent (saves rules during install). Save rules manually: iptables-save > /etc/iptables/rules.v4 (Debian) or iptables-save > /etc/sysconfig/iptables (RHEL). RHEL/CentOS: install and enable iptables-services: yum install iptables-services && systemctl enable iptables. Verify rules load on boot: reboot and check with iptables -L -n -v. Consider migrating to nftables or firewalld which have built-in persistence. If these steps do not resolve the issue, consider consulting additional resources or a qualified professional.

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