+ ifname_server
+ Virtual interface name on the server. [shippo%d]
+ ifname_client
+ Virtual interface name on the client. [hippo%d]
+ Any %d is interpolated (by the kernel).
+
+Ordinary settings, used by server only:
+
+ max_clock_skew
+ Permissible clock skew between client and server.
+ hippotat will not work if clock skew is more than this.
+ Conversely: when moving client from one public network to
+ another, the first network can deny service to the client for
+ this period after the client leaves the first network.
+ [300s]
+