See the section called “Access Control Options” for information on limiting the
hosts that may connect to the listening Ncat process.
--listen (Listen for connections)
Listen for connections rather than connecting to a remote
--max-conns (Specify maximum number of connections)
The maximum number of simultaneous connections accepted by an Ncat
instance. 100 is the default.
--keep-open (Accept multiple connections)
Normally a listening server accepts only one connection and
then quits when the connection is closed. This option makes it accept
multiple simultaneous connections and wait for more connections after
they have all been closed. It must be combined with
--listen. In this mode there is no way for Ncat to
know when its network input is finished, so it will keep running
until interrupted. This also means that it will never close its
output stream, so any program reading from Ncat and looking for
end-of-file will also hang.
--broker (Connection brokering)
Allow multiple parties to connect to a centralised Ncat server
and communicate with each other. Ncat can broker communication between
systems that are behind a NAT or otherwise unable to directly connect.
This option is used in conjunction with
--listen port to have broker mode enabled.
--chat (Ad-hoc “chat server”)
--chat option enables chat mode, intended
for the exchange of text between several users. In chat mode,
connection brokering is turned on. Ncat prefixes each message received
with an ID before relaying it to the other connections. The ID is
unique for each connected client. This helps distinguish who sent
what. Additionally, non-printing characters such as control characters
are escaped to keep them from doing damage to a terminal.