Peter Radcliffe wrote: >Willem Jan Withagen <[email protected]> probably said: > > >>I also have portsentry in a rather sensitive mode doing exactly the same >>thing. >>Trigger one of the "backdoor" ports, and you're out of my game. >> >> > >The general problm with this type of reactive filtering is that if >someone can spoof the source addresses effectively or cause a connection >from a legitimate host you've just DoSed yourself... > >Personally I only allow ssh from known legitimate sources and block the >rest so the "noise" is in a completely different list. > > I do too, on systems that are completly mine. But I had to "force" this customer to refrain from using ftp/telnet/... with plain open passwords. And access to this box is required from verious remote locations with yet unknown IPs. So I have little chances there. As far as I know, you need to go thru a lot of trouble to complete a spoofed full 3-way handshake just to get my maintenace IP-number blocked. Next to the fact that there is a rule before the blocked list which lets me in anyways.... :) --WjW _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-security To unsubscribe, send any mail to "[email protected]"