digraph G {
    node [ shape=box ]
    rankdir=TB;

    label="IPv4-to-IPv6 proxy by ungleich.ch"

    proxyv4 [ label="ungleich\nIPv4-IPv6 Proxy" ];

    serverv6  [ label="Your IPv6 only\nServer" ];

    clientv4 [ label="IPv4 only\nclient" ];
    clientv6 [ label="IPv6 only\nclient" ];

    clientv6->serverv6 [ label="Direct IPv6 access" ];
    clientv4->proxyv4 [ label="Connect by IPv4" ];
    proxyv4->serverv6 [ label="Translate to IPv6" ];


}