suggests a configuration option for FreeBSD that tells the system to drop all packages arriving from the network to a closed port and thus somewhat securing your system and also saving some upload bandwidth as well as cpu time. These are the shell commands to run:
sysctl net.inet.tcp.blackhole=2 sysctl net.inet.udp.blackhole=1
and this you should also insert to the /etc/sysctl.conf file so the settings survive a server reboot:
That's cool so far, but. My Fedora Linux box keeps saying
error: "net.inet.tcp.blackhole" is an unknown key
The quoted parameter names are not listed under /proc/sys, and not returned by sysctl -a.
I found no reference to this problem online. Am I missing something? Do these parameter names differ under Fedora? Do I need some additional package to have this functionality?
Any help is greatly appreciated.