`enable`: `boolean` :: Enable host firewall rules. `log_level_in`: `(alert | crit | debug | emerg | err | info | nolog | notice | warning)` :: Log level for incoming traffic. `log_level_out`: `(alert | crit | debug | emerg | err | info | nolog | notice | warning)` :: Log level for outgoing traffic. `ndp`: `boolean` :: Enable NDP. `nf_conntrack_max`: `integer (32768 - N)` :: Maximum number of tracked connections. `nf_conntrack_tcp_timeout_established`: `integer (7875 - N)` :: Conntrack established timeout. `nosmurfs`: `boolean` :: Enable SMURFS filter. `smurf_log_level`: `(alert | crit | debug | emerg | err | info | nolog | notice | warning)` :: Log level for SMURFS filter. `tcp_flags_log_level`: `(alert | crit | debug | emerg | err | info | nolog | notice | warning)` :: Log level for illegal tcp flags filter. `tcpflags`: `boolean` :: Filter illegal combinations of TCP flags.