-be expressed as an IP address (not a DNS name). For \fBssl\fR, the
-\fB\-\-private\-key\fR, \fB\-\-certificate\fR, and \fB\-\-ca\-cert\fR
-options are mandatory.
+be expressed as an IP address (not a DNS name) in IPv4 or IPv6 address
+format. Wrap IPv6 addresses in square brackets,
+e.g. \fBtcp:[::1]:6633\fR. For \fBssl\fR, the \fB\-\-private\-key\fR,
+\fB\-\-certificate\fR, and \fB\-\-ca\-cert\fR options are mandatory.