Major NPF improvements (merge from upstream):

- Switch to the C11-style atomic primitives using atomic_loadstore(9).

- npfkern: introduce the 'state.key.interface' and 'state.key.direction'
settings. Users can now choose whether the connection state should be
strictly per-interface or global at the configuration level. Keep NAT
logic to be always per-interface, though.

- npfkern: rewrite the G/C worker logic and make it self-tuning.

- npfkern and libnpf: multiple bug fixes; add param exporting; introduce
more parameters. Remove npf_nvlist_{copyin,copyout}() functions and
refactor npfctl_load_nvlist() with others; add npfctl_run_op() to have
a single entry point for operations. Introduce npf_flow_t and clean up
some code.

- npfctl: lots of fixes for the 'npfctl show' logic; make 'npfctl list'
more informative; misc usability improvements and more user-friendly
error messages.

- Amend and improve the manual pages.

Use -width Pa for FILES.

Fix pasto in table replace -t type

npfctl: implement table replace subcommand.
Contributed by Timshel Knoll-Miller.

branches: 1.21.2;
Major NPF improvements:
- Convert NPF connection table to thmap. State lookup is now lock-free.
- Improve connection state G/C: it is now incremental and tunable.
- Add support for dynamic NAT address. Translation addresses can now be
selected from a pool of addresses. There are two selection algorithms,
"ip-hash" and "round-robin" (see the man page).
- Translation address can be specified as e.g. ifaddrs(wm0) in npf.conf
to dynamically choose an IP from the interface address(es).
- Add support for the NETMAP algorithm with static NAT for net-to-net
translation (it is equivalent to iptables NETMAP logic).
- Convert 'ipset' tables to use thmap; the table lookup is now lock-free.
- Misc improvements, bug fixes and more unit tests.
- Bump NPF_VERSION (will also bump libnpf).

branches: 1.20.2; 1.20.4;
npfctl: add support for the 'no-ports' flag in the 'map' statements.
This allows us to create a NAT policy without the port translation.

Document list

branches: 1.18.2;
Fix typo. From Michael Scherer in PR 51162.

Cross-link npf(7).

NPF: rework of the connection saving and restoring:
- Add support for saving a snapshot of the current connections together
with a full configuration. Support a reverse load operation. Eliminate
the old 'sess-save' and 'sess-load' in favour of the new mechanism.
- Share code between load and reload operations: the latter performs
load from npf.conf without affecting the connections.
- Simplify and fix races with connection loading.
- Bump NPF_VERSION.

branches: 1.15.2;
Remove trailing whitespace.

npfctl: remove some n-code leftovers, fix the build, update the man pages.

- Convert NPF dynamic rule ID to just incremented 64-bit counter.
- Fix multiple bugs. Also, update the man page.

NPF:
- Implement dynamic NPF rules. Controlled through npf(3) library of via
npfctl rule command. A rule can be removed using a unique identifier,
returned on addition, or using a key which is SHA1 hash of the rule.
Adjust npftest and add a regression test.
- Improvements to rule inspection mechanism.
- Initial BPF support as an alternative to n-code.
- Minor fixes; bump the version.

npfctl: add 'validate' command to check the config, but not load it. Update
the man page. Also add a small note about 'debug' command, PR/47298.

npfctl(8): mention table listing.

branches: 1.9.2;
- npfctl show: add most of the missing cases.
- Few minor improvements to NPF man pages.

NPF improvements:
- Add NPF_OPCODE_PROTO to match the address and/or protocol only.
- Update parser to support arbitrary "pass proto <name/number>".
- Fix IPv6 address and protocol handling (add a regression test).
- Fix few theorethical races in session handling module.
- Misc fixes, simplifications and some clean up.

Fix and update npf.conf(5), npfctl(8) and its usage message.

branches: 1.6.4; 1.6.6;
As per request from the author, put non-standard PERFORMANCE back.

Use 'offset indent' for the list of commands. Emphasize valid commands.
Remove PERFORMANCE (too small paragraph to warrant a section).

NPF checkpoint:
- Add the concept of rule procedure: separate normalization, logging and
potentially other functions from the rule structure. Rule procedure can be
shared amongst the rules. Separation is both at kernel level (npf_rproc_t)
and configuration ("procedure" + "apply").
- Fix portmap sharing for NAT policy.
- Update TCP state tracking logic. Use TCP FSM definitions.
- Add if_byindex(), OK by matt@. Use in logging for the lookup.
- Fix traceroute ALG and many other bugs; misc clean-up.

Fix remaining references for npf.conf(8) to npf.conf(5)

Move npf.conf(5-8) into the correct section, hence npf.conf(5).

Import NPF - a packet filter. Some features:

- Designed to be fully MP-safe and highly efficient.

- Tables/IP sets (hash or red-black tree) for high performance lookups.

- Stateful filtering and Network Address Port Translation (NAPT).
Framework for application level gateways (ALGs).

- Packet inspection engine called n-code processor - inspired by BPF -
supporting generic RISC-like and specific CISC-like instructions for
common patterns (e.g. IPv4 address matching). See npf_ncode(9) manual.

- Convenient userland utility npfctl(8) with npf.conf(8).

NOTE: This is not yet a fully capable alternative to PF or IPFilter.
Further work (support for binat/rdr, return-rst/return-icmp, common ALGs,
state saving/restoring, logging, etc) is in progress.

Thanks a lot to Matt Thomas for various useful comments and code review.
Aye by: board@