To enable hole punching in go-libp2p, you can follow these steps:

1. Use the libp2p.New function with the libp2p.EnableHolePunching() option. This will enable hole punching in your go-libp2p application. Here's an example of how to use it:

host, err := libp2p.New(context.Background(), libp2p.EnableHolePunching())
if err != nil {
    log.Fatal(err)
}

2. When connecting to other peers, hole punching should work automatically if relays are available. Relays are intermediary nodes that help establish connections between peers. If relays are not available, hole punching may not be successful.

3. Additionally, you can use other options to further enhance hole punching capabilities. Two such options are libp2p.EnableAutoRelay() and autorelay.WithPeerSource(). These options can be used in conjunction with libp2p.New to improve hole punching. Here's an example:

host, err := libp2p.New(context.Background(), libp2p.EnableHolePunching(), libp2p.EnableAutoRelay(), autorelay.WithPeerSource(myPeerSource))
if err != nil {
    log.Fatal(err)
}

• The libp2p.EnableAutoRelay() option enables automatic relaying when hole punching is not possible directly between peers.
• The autorelay.WithPeerSource() option allows you to specify a custom peer source for relaying. This can be useful if you have a specific set of peers that you want to use as relays.

Please note that the availability and effectiveness of hole punching may vary depending on network conditions and the presence of relays.