.IP "\fBpssl:\fR[\fIport\fR][\fB:\fIhost\fR]"
.IQ "\fBptcp:\fR[\fIport\fR][\fB:\fIhost\fR]"
Listens for OpenFlow connections on \fIport\fR.  The default
\fIport\fR is 6653.  By default, connections are allowed from any IPv4
address.  Specify \fIhost\fR as an IPv4 address or a bracketed IPv6
address (e.g. \fBptcp:6653:[::1]\fR).  On Linux, use \fB%\fIdevice\fR
to designate a scope for IPv6 link-level addresses,
e.g. \fBptcp:6653:[fe80::1234%eth0]\fR.  DNS names can
be used if built with unbound library.  For \fBpssl\fR, the
\fB\-\-private\-key\fR,\fB\-\-certificate\fR, and \fB\-\-ca\-cert\fR
options are mandatory.
.IP
.
.IP "\fBpunix:\fIfile\fR"
Listens for OpenFlow connections on the Unix domain server socket
named \fIfile\fR.