pssl:[port][:host]
    Listens for OpenFlow connections on port. The default port is 6653. By default, connections are allowed from any IPv4 address. Specify host as an IPv4 address or a bracketed IPv6 address (e.g. ptcp:6653:[::1]). On Linux, use %device to designate a scope for IPv6 link-level addresses, e.g. ptcp:6653:[fe80::1234%eth0]. DNS names can be used if built with unbound library. For pssl, the --private-key,--certificate, and --ca-cert options are mandatory.

punix:file
    Listens for OpenFlow connections on the Unix domain server socket named file.