present participle of knock boots

present participle of knock wood

present participle of knock on wood

present participle of knock back

present participle of knock out

present participle of knock together

present participle of knock off

present participle of knock over

present participle of knock for a loop

(networking) A means of securing ports on a firewall by requiring the host to attempt to connect to a prespecified sequence of closed ports before being allowed access to the desired port.