iptables-restore

Restore the iptables configuration from a file

$ sudo iptables-restore [path/to/file]

iptables-restore [options] < filename

-c, --counters
    Restore counters as well as rules.

-n, --noflush
    Don't flush the chain before restoring.

-w, --wait
    Wait for specified number of seconds for xtables lock.

-W, --wait-interval
    Wait interval in microseconds. Must be used with -w.

-T, --test
    Don't change anything, just exit with zero code if correct, or non-zero if there are errors.

-v, --verbose
    Display verbose output during restore process.

-V, --version
    Display program version.

-h, --help
    Display help text.

The `iptables-restore` command reads iptables rule configurations from a file (typically created by `iptables-save`) and applies them to the Linux kernel's iptables firewall. This allows administrators to easily save and restore firewall configurations, making it ideal for automated deployments, system recovery, and applying predefined security policies.

It provides a reliable method for quickly implementing complex rule sets without manually entering each rule individually. `iptables-restore` processes the input file line by line, adding or replacing rules as specified. It's crucial to ensure that the file is properly formatted and contains valid iptables rules to avoid errors during the restoration process.

The utility attempts to apply all rules and will report any errors encountered during the process. If a rule fails to apply, it will continue processing subsequent rules. Proper testing in a safe environment is recommended before applying configuration changes to production systems.

Incorrectly formatted input files can lead to unexpected firewall behavior or system instability. Always validate input files before using `iptables-restore` on a production system. Be aware that `iptables-restore` operates on the currently active iptables configuration; therefore, any existing rules not present in the input file may be affected (potentially removed, unless `-n` is used).

The input file for `iptables-restore` should follow the format output by `iptables-save`. Each table (filter, nat, mangle, raw) is defined with a header, followed by the chain definitions and rules. Comments can be included using the '#' character at the beginning of a line.

`iptables-restore` attempts to restore all rules even if some fail. It will report the number of errors encountered. Use the `-v` flag to see details about what rules failed and why.

The `iptables-restore` command was developed as part of the iptables project, evolving alongside the netfilter framework in the Linux kernel. It aimed to provide a convenient way to manage and persist firewall rules beyond a single system session. Its creation was driven by the need for a more structured and manageable approach compared to manually entering iptables rules repeatedly. The command's usage has become widespread in system administration, DevOps, and cloud environments for configuring network security.

iptables(8), iptables-save(8)