Exposing services on the Internet is a requirement for FreedomBox and a very tricky problem.

Topologies:

||<rowbgcolor="#E0E0FF"> Topology || Frequency || Static || Reachable v4 || Reachable v6 ||
|| ADSL w NAT+UPNP || common || n || y || y? ||
|| ADSL w NAT      || common || n || n || y? ||
|| 4G              || common || n || n || n ||
|| Pure IPv6       || rare   || y || n || y ||

Methods:

||<rowbgcolor="#E0E0FF"> Method || [[#customclient|Client configuration]] || Reliability || Bandwidth & latency || [[#metadata|Protect metadata]] || [[#centralized|Centralized]] || Paid || Protocols ||
|| [[https://en.wikipedia.org/wiki/STUN|STUN]] [[https://en.wikipedia.org/wiki/Interactive_Connectivity_Establishment|ICE]] [[https://en.wikipedia.org/wiki/Traversal_Using_Relays_around_NAT|TURN]] || none || low  || good || no      || no || no || UDP ||
|| Tor Onion Service || hard || good || poor    || no || no || no || TCP ||
|| Pagekite  || none || good || good || partial || yes || yes || TCP ||
|| IPv6      || hard || good || medium || no    || yes || no  || all ||
|| VPN       || none || high || good || partial || yes || yes || all ||
|| UPNP      || none || poor || high || no      || yes || no  || all ||
|| Port forwarding on router || none || high || high || no      || yes || no  || all ||
|| Port forwarding using VPS || none || high || high || no      || yes || yes  || all ||
|| Miredo/Teredo tunnel || || good || medium || no || yes || no || IPv6 ||

<<Anchor(customclient)>> Client configuration: if client requires daemons (e.g. Tor), libraries, a non-trivial configuration, or other invasive changes like switching to a different ISP.

<<Anchor(metadata)>> Metadata protection: Whereas an eavesdropper can tell the source and destination IP address of the connection, timing, amount of data. "partial": when only the source or the destination IP address is leaked.