Add iptables parsing script

[TotallyMonica]

Summary

This PR creates a script that parses iptables and ip6tables rules, collecting the following metrics per rule:

• Table
• Chain
• Rule's line number
• Action (Labeled in iptables -L and ip6tables -L as target)
• Protocol
• Incoming interface
• Outgoing interface
• Source address
• Destination address
• Extra information
• Rule hit statistics
  • Byte count (as iptables_bytes_total and ip6tables_bytes_total)
  • Packet count (as iptables_packets_total and ip6tables_bytes_total)

References

PR is largely based on prometheus/node_exporter#1264, implementing the feedback received by it. As such, no files are being written to or read from.

Notes

Due to how iptables is designed, iptables must be ran as uid 0, so this means one of the following:

• /sbin/iptables must be setuid
• iptables.py must be ran as root
• /sbin/iptables must have the capabilities CAP_NET_ADMIN+ep

Testing done

• Hosts
  • Ubuntu 24.04.3 Server with iptables v1.8.10
  • Debian 13.2 with iptables v1.8.11