Ncat can use TCP, UDP, SCTP, SSL, IPv4, IPv6, and various combinations
of these. TCP over IPv4 is the default.
the Transmission Control Protocol, is the reliable protocol that
underlies a great deal of Internet traffic. Ncat makes TCP connections
by default. TCP may be combined with SSL.
the User Datagram Protocol, is an unreliable protocol often used by
applications that can't afford the overhead of TCP. Use the
option to make Ncat use UDP. In listen mode, Ncat will communicate
with only one client, and the
option doesn't work, the reason for this being that UDP has no notion
of a connection. UDP may be secured by a form of SSL called Datagram TLS (DTLS).
This is currently only supported in connect (client) mode.
the Stream Control Transmission Protocol, is a newer reliable
protocol. It is selected with the
option. Ncat uses a TCP-compatible subset of SCTP features, not
including multiple streams per connection or message boundaries. SCTP
may be combined with SSL.
(Secure Sockets Layer) or
TLS (Transport Layer Security) provides security to network traffic
when used properly. Use the
to turn SSL on; it works with TCP or SCTP. See the section called “SSL” for instructions and caveats.
the Internet Protocol version 4, is the most popular version of the
Internet Protocol in use. Using the
puts Ncat into IPv4-only mode; only IPv4 addresses will be used even
if, for example, as hostname resolves to IPv6 addresses as well.
is the lesser-used successor to IPv4. Use
to put Ncat into IPv6-only mode.
By default, Ncat will listen on both IPv4 and IPv6, and will connect to
resolved addresses in the order they are returned by the operating system.