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NPF-PARAMS(7) FreeBSD Miscellaneous Information Manual NPF-PARAMS(7) NAME npf-params - tunable NPF parameters DESCRIPTION NPF supports a set of dynamically tunable parameters. All parameter values are integers and should generally be between zero and INT_MAX, unless specified otherwise. Some parameters values can be negative; such values would typically have a special meaning. Enable/disable switches should be represented as boolean values 0 ("off") or 1 ("on"). PARAMETERS bpf.jit BPF just-in-time compilation: enables or disables bpfjit(4) support. Some machine architectures are not presently supported by bpfjit(4). Setting this parameter to off stops NPF from trying to enable this functionality, and generating a warning if it is unable to do so. Default: 1. ip4.reassembly Perform IPv4 reassembly before inspecting the packet. Fragmentation is considered very harmful, so most networks are expected to prevent it; reassembly is enabled by default. However, while the packet should generally be reassembled at the receiver, reassembly by the packet filter may be necessary in order to perform state tracking. Default: 1. ip6.reassembly Perform IPv6 reassembly before inspecting the packet. Discouraged in general but not prohibited by RFC 8200. Default: 0. gc.step Number of connection state items to process in one garbage collection (G/C) cycle. Must be positive number. Default: 256. gc.interval_min The lower bound for the sleep time of the G/C worker. The worker is self-tuning and will wake up more frequently if there are connections to expire; it will wake up less frequently, diverging towards the upper bound, if it does not encounter expired connections. Default: 50 (in milliseconds). gc.interval_max The upper bound for the sleep time of the G/C worker. Default: 5000 (in milliseconds). state.key The connection state is uniquely identified by an n-tuple. The state behavior can be controlled by including (excluding) some of the information in (from) the keys. interface Include interface identifier into the keys, making the connection state strictly per-interface. Default: 1. direction Include packet direction into the keys. Default: 1. state.generic Generic state tracking parameters for non-TCP flows. All timeouts are in seconds and must be zero or positive. timeout.new Timeout for new ("unsynchronized") state. Default: 30. timeout.established Timeout for established ("synchronized") state. Default: 60. timeout.closed Timeout for closed state. Default: 0. state.tcp State tracking parameters for TCP connections. All timeout values are in seconds. max_ack_win Maximum allowed ACK window. Default: 66000. strict_order_rst Enforce strict order RST. Default: 1. timeout.new Timeout for a new connection in "unsynchronized" state. Default: 30. timeout.established Timeout for an established connection ("synchronized" state). Default: 86400. timeout.half_close Timeout for the half-close TCP states. Default: 3600. timeout.close Timeout for the full close TCP states. Default: 10. timeout.time_wait Timeout for the TCP time-wait state. Default: 240. portmap.min_port Lower bound of the port range used when selecting the port for dynamic NAT with port translation enabled. Default: 1024 (inclusive; also the lowest allowed value). portmap.max_port Upper bound of the port range as described above. Default: 49151 (inclusive; 65535 is the highest allowed value). EXAMPLES An example line in the npf.conf(5) configuration file: set state.tcp.strict_order_rst on # "on" can be used instead of 1 set state.tcp.timeout.time_wait 0 # destroy the state immediately SEE ALSO libnpf(3), npfkern(3), bpfjit(4), npf.conf(5), pcap-filter(7), npfctl(8) AUTHORS NPF was designed and implemented by Mindaugas Rasiukevicius. FreeBSD 14.1-RELEASE-p8 May 31, 2020 FreeBSD 14.1-RELEASE-p8