.IP "\fBpssl:\fIport\fR[\fB:\fIip\fR]"
Listen on the given SSL \fIport\fR for a connection.  By default,
connections are not bound to a particular local IP address and
it listens only on IPv4 (but not IPv6) addresses, but
specifying \fIip\fR limits connections to those from the given
\fIip\fR, either IPv4 or IPv6 address.  If \fIip\fR is
an IPv6 address, then wrap \fIip\fR with square brackets, e.g.:
\fBpssl:6640:[::1]\fR.  The \fB\-\-private\-key\fR,
\fB\-\-certificate\fR, and \fB\-\-ca\-cert\fR options are mandatory
when this form is used.
.
.IP "\fBptcp:\fIport\fR[\fB:\fIip\fR]"
Listen on the given TCP \fIport\fR for a connection.  By default,
connections are not bound to a particular local IP address and
it listens only on IPv4 (but not IPv6) addresses, but
\fIip\fR may be specified to listen only for connections to the given
\fIip\fR, either IPv4 or IPv6 address.  If \fIip\fR is
an IPv6 address, then wrap \fIip\fR with square brackets, e.g.:
\fBptcp:6640:[::1]\fR.
.
.IP "\fBpunix:\fIfile\fR"
On POSIX, listen on the Unix domain server socket named \fIfile\fR for a
connection.
.IP
On Windows, listen on a kernel chosen TCP port on the localhost. The kernel
chosen TCP port value is written in \fIfile\fR.