Hello On 20.01.14 12:31, sa9k063 wrote: > can someone please explain: > > one of my boxes gets portscanned often by some likely infected laptops. > While having set > > net.inet.tcp.blackhole=3D1 > > there are still messages like > > +Limiting closed port RST response from 348 to 200 packets/sec According to the blackhole(4) manpage (from a FreeBSD 9.1 system): ---8<------------------------------------------------------------ SYNOPSIS sysctl net.inet.tcp.blackhole[=3D[0 | 1 | 2]] sysctl net.inet.udp.blackhole[=3D[0 | 1]] Part of DESCRIPTION: Normal behaviour, when a TCP SYN segment is received on a port = where there is no socket accepting connections, is for the system = to return a RST segment, and drop the connection. The connecting = system will see this as a =93Connection refused=94. By setting the = TCP blackhole MIB to a numeric value of one, the incoming SYN = segment is merely dropped, and no RST is sent, making the system = appear as a blackhole. By setting the MIB value to two, any = segment arriving on a closed port is dropped without returning a = RST. This provides some degree of protection against stealth = port scans. ---8<------------------------------------------------------------ So it is possible, that you are hit with something else then SYN = packets and should probably set net.inet.tcp.blackhole=3D2, or even = with UDP packets, then also set net.inet.udp.blackhole=3D1. What output does 'sysctl -a | grep blackhole' show? bye Fabian _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-security To unsubscribe, send any mail to "[email protected]"