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.

To ask for entrance or admission into. / Used other than figuratively or idiomatically: see knock, on, the, door, of.

(bingo) four

simple past tense and past participle of knock on the door of

present participle of knock at the door of

Third-person singular simple present indicative form of knock on the door of

simple past tense and past participle of knock at the door of

present participle of knock on the door of

Alternative form of knock on the door of