TCP/IP hardening, take two

I cleaned up the previously posted patches, tested them a little more, and added a sysctl knob for logging SYN+FIN packets (before optionally dropping them). A FreeBSD 4.0-CURRENT machine with these patches and no firewall looks like this to nmap (with tcp.drop_synfin and tcp.restrict_rst enabled)

TCP/IP hardening, take two

I cleaned up the previously posted patches, tested them a little more, and added a sysctl knob for logging SYN+FIN packets (before optionally dropping them). A FreeBSD 4.0-CURRENT machine with these patches and no firewall looks like this to nmap (with tcp.drop_synfin and tcp.restrict_rst enabled