Chat Example

[agahEbrahimi]

Hello,

I was wondering how I would be able to give a non local IP to the chat example. When running the executable, a port is given to it, but how would I be able to set it so that it works with the public IP and not the local IP (127.0.0.1).

Thank you in advance,
Agah Ebrahimi

[Stebalien]

The chat example actually listens on 0.0.0.0 (the global ip4 address) by default.

[agahEbrahimi]

but that's not the case for the sender, is it? wouldn't I have to set the public address for the sender address if I want to communicate over the internet?

[Stebalien]

@agahEbrahimi yes. You can do that by specifying ./chat -d /ip4/0.0.0.0/tcp/3001 (the all address).

[agahEbrahimi]

Hmm, it doesn't seem to be working, it gives protocol not found in multiaddr as an error.

[upperwal]

0.0.0.0 in the code means listen to all IPv4 addresses (ie. accept connects from all)

Try this if you want to run it on a public network.

Simple Case: Atleast one public IP

Run this on a system with public IP address:

./chat -sp 3000

It should output something like this
Run './chat -d /ip4/127.0.0.1/tcp/3000/ipfs/<node_id>' on another console.

Now replace 127.0.0.1 with the public IP of the previous system and execute

./chat -d /ip4/<public_ip>/tcp/3000/ipfs/<node_id>

on any system (public or private ip)

Not so simple case: Different private networks
This example does not support this. You need to enable discovery and port mapping for this.

[agahEbrahimi]

I'm not requesting anything but having a chat example with both discovery and port mapping would be awesome (just as a suggestion).

[Stebalien]

I'm currently working on a refactor that should make setting up port mapping easier. Once that gets merged, we can improve the examples.

[agahEbrahimi]

Awesome :)

[upperwal]

@Stebalien Would it be possible to share these changes? It would also be great if more NAT traversal techniques (NAT hole punching and STUN) are added to libp2p-nat. Let me know what do you think about it.

[Stebalien]

Actually, I forgot. @jvsteiner already added a nice option for configuring NAT port mapping. Pass the NATPortMap() option to libp2p.New(...).

---

We actually have three nat-traversal solutions at the moment:

1. UPnP (NATPortMap): We try to ask the router to open a port for us.
2. Custom hole-punching/STUN through a combination of peer-routing, external-address/port discovery, and reuseport (we try to use one local port for all inbound and outbound connections).
3. Custom TURN (in-progress) through go-libp2p-circuit. Unfortunately, we don't currently advertise relayed addresses by default but we're working on that.

[jvsteiner]

FYI, I'm guessing one probably needs to use the routed host for some of those NAT techniques to work.

[upperwal]

@Stebalien Is NATPortMap not deprecated.

go-libp2p/p2p/host/basic/basic_host.go

Lines 50 to 51 in 3b8f227

	// This option is deprecated in favor of HostOpts and NewHost.
	const NATPortMap Option = iota

libp2p uses https://github.com/fd/go-nat repo for NAT and I could only find NAT UPnP and NAT-PMP, could you please point me to STUN implementation used in libp2p.

[upperwal]

@Stebalien I think https://github.com/libp2p/go-reuseport is the repo for STUN but its not being used in libp2p.

[Stebalien]

@upperwal

Is NATPortMap not deprecated.

That option is (technically) deprecated but NATPortMap isn't. That comment is just telling you to configure the nat manager using the HostOpts instead of passing that option to NewHost.

@Stebalien I think https://github.com/libp2p/go-reuseport is the repo for STUN but its not being used in libp2p.

It's used by go-tcp-transport which is used by go-libp2p-swarm for TCP connections.

[upperwal]

@Stebalien Ok. Got it. Thanks.