`enable`: `` :: Enable host firewall rules. `log_level_in`: `` :: Log level for incoming traffic. `log_level_out`: `` :: Log level for outgoing traffic. `ndp`: `` :: Enable NDP. `nf_conntrack_max`: ` (32768 - N)` :: Maximum number of tracked connections. `nf_conntrack_tcp_timeout_established`: ` (7875 - N)` :: Conntrack established timeout. `nosmurfs`: `` :: Enable SMURFS filter. `smurf_log_level`: `` :: Log level for SMURFS filter. `tcp_flags_log_level`: `` :: Log level for illegal tcp flags filter. `tcpflags`: `` :: Filter illegal combinations of TCP flags.