feat: update autonat.md

content/concepts/nat/autonat.md

@@ -44,13 +44,13 @@ If most of these dial attempts are successful, the node can be reasonably sure
 that it is not behind a NAT. On the other hand, if most of these dial attempts fail,
 it strongly indicates that a NAT is blocking incoming connections.
 
-{{< alert icon="" context="">}}
-Currently, AutoNAT cannot test individual addresses,
-but a [proposal](https://github.com/libp2p/specs/issues/503) for AutoNAT v2 aims to
-add this capability.
-{{< /alert >}}
+## AutoNAT v1 vs v2
+
+libp2p supports two versions of the AutoNAT protocol:
+
+### AutoNAT v1
 
-The AutoNAT protocol uses the protocol ID `/libp2p/autonat/1.0.0` and involves
+AutoNAT v1 uses the protocol ID `/libp2p/autonat/1.0.0` and involves
 the exchange of `Dial` and `DialResponse` messages.
 
 To initiate the protocol, a node sends a `Dial` message to another peer containing
@@ -67,6 +67,57 @@ whether or not it is behind a NAT.
 > an error, the node is likely behind a NAT and may need to use a
 > [relay server]({{< relref "/concepts/nat/dcutr.md" >}}) to communicate with other nodes in the network.
 
+AutoNAT v1 determines reachability at the node level and it cannot distinguish whether
+specific addresses (e.g., IPv4 vs IPv6) are reachable independently.
+
+### AutoNAT v2
+
+AutoNAT v2 extends the original protocol with the ability to determine reachability
+for **individual addresses**. This enables nodes to:
+
+- Check reachability separately for IPv4, IPv6, and WebTransport/WebRTC addresses
+- Know exactly which addresses are publicly accessible
+- Make smarter decisions about which addresses to advertise
+
+AutoNAT v2 uses the protocol ID `/libp2p/autonat/2.0.0`.
+
+#### Querying confirmed addresses
+
+In go-libp2p, you can query addresses that have been confirmed as reachable using
+the `ConfirmedAddrs()` method:
+
+```go
+// Get addresses confirmed reachable by AutoNAT v2
+confirmedAddrs := host.ConfirmedAddrs()
+for _, addr := range confirmedAddrs {
+    fmt.Println("Confirmed reachable:", addr)
+}
+```
+
+#### Subscribing to reachability changes
+
+You can subscribe to the `EvtHostReachableAddrsChanged` event to be notified when
+the set of reachable addresses changes:
+
+```go
+sub, err := host.EventBus().Subscribe(new(event.EvtHostReachableAddrsChanged))
+if err != nil {
+    log.Fatal(err)
+}
+defer sub.Close()
+
+for evt := range sub.Out() {
+    e := evt.(event.EvtHostReachableAddrsChanged)
+    fmt.Println("Reachable addresses changed:", e.Addrs)
+}
+```
+
+{{< alert icon="" context="info">}}
+AutoNAT v2 is available in go-libp2p v0.42.0 and later.
+{{< /alert >}}
+
+## Security considerations
+
 {{< alert icon="" context="caution">}}
 To prevent
 [certain types of attacks](https://www.rfc-editor.org/rfc/rfc3489#section-12.1.1),

content/concepts/nat/hole-punching.md

@@ -113,7 +113,8 @@ a hole punching phase.
    - `Other_Peers` attempt to dial each of `B`'s addresses and report the
      outcome back to `B`.
    - Based on the reports, `B` can gauge whether it is publicly dialable and
-     determine if hole punching is needed.
+     determine if hole punching is needed. With AutoNAT v2, `B` can determine
+     reachability for each address individually (e.g., IPv4 vs IPv6).
 
    <!-- to add routing reference when available -->
    <!-- to add autorelay reference when available -->