.TH pknlusr 8 "2020-10-22" "xtables-addons" "xtables-addons" .SH NAME .PP pknlusr \(em userspace monitor for successful xt_pknock matches .SH Synopsis .PP \fBpknlusr\fP [\fIgroup-id\fP] .SH Description \fIxt_pknock\fP is an xtables match extension that implements so-called \fIport knocking\fP. It can be configured to send information about each successful match via a netlink socket to userspace. \fBpknluser\fP listens for these notifications. .PP By default, \fBpknlusr\fP listens for messages sent to netlink multicast group 1. Another group ID may be passed as a command-line argument. .SH See also .PP xtables-addons(8)