Allow source NAT to use interface networks #9220
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The old interface only lists interface addesses, not nets, and the rule parser parser only looks for interface names suffixed by "ip". In pf, interface address is used dynamically by being surrounded by parenthesis and includes the ":0" modifier to exclude aliases. By combining this with the ":network" modifier, source nat can also use an interface's network, dynamically, i.e. "($iface:network:0)". This is different to one-to-one nat because the source and target networks do not need to be the same size. Any of pf's pool options are valid in this situation. Signed-off-by: Steve Kerrison <[email protected]>
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The old interface only lists interface addesses, not nets, and the rule parser parser only looks for interface names suffixed by
ip. In pf, interface address is used dynamically by being surrounded by parenthesis and includes the ":0" modifier to exclude aliases. By combining this with the ":network" modifier, source nat can also use an interface's network, dynamically, i.e. "($iface:network:0)".This is different to one-to-one nat because the source and target networks do not need to be the same size. Any of pf's pool options are valid in this situation.
Noticing PR #8495, I think updating the refactoring done there to include support for this would be fairly simple, with an update around https://github.com/opnsense/core/pull/8495/files#diff-fa864e1de379b514cb12d89d3e3c738b31c6c340fba099be98ba03520035c676R79
I made these changes because I wanted to source NAT onto a prefix delegated subnet, where the source subnet is larger than the target prefix and so masking/NPTv6 won't work, and the prefix is dynamic (DHCP assigned by ISP) so so must be based on an interface reference.