In this directory, you can create the following filenames to add
custom rules at each section of the firewall script:
ipv4_custom_allowedports ipv4_custom_mssclamp ipv4_custom_proto
ipv4_custom_blockincoming ipv4_custom_nat ipv4_custom_routing
ipv4_custom_blockoutports ipv4_custom_notrack ipv4_custom_flush
ipv4_custom_conntrack ipv4_custom_portforward ipv4_custom_trust
ipv4_custom_blockip ipv4_custom_mark
ipv6_custom_flush ipv6_custom_trust ipv6_custom_mssclamp
ipv6_custom_blockoutports ipv6_custom_allowedports ipv6_custom_conntrack
ipv6_custom_routing ipv6_custom_blockincoming
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