Xud: Verify that my own xud is reachable

[moshababo]

If listening to P2P connection, verify that listenPort is reachable by the node's external IP.
If it's not alert that the node is not reachable.

181 is a prerequisite.

[kilrau]

If result is 'not reachable', print notification:
{Port 8885 is not reachable, xud is not reachable for inbound connections.}

Notes:
Verify that node is reachable check should be executed only once on xud launch for now.

[kilrau]

Please let me know what you think @moshababo @sangaman @offerm @michael1011

[sangaman]

I'm actually not sure I follow this issue, is this about verifying the listening addresses that peers share with us on handshake? Why would we try something besides what they shared with us?

[kilrau]

This is about verifying, that my own externalIP+Port is reachable.

[sangaman]

Ah thanks for clarifying, so it's something we would do just once on startup.

[offerm]

I think that we should avoid guessing. for sure not without the user asking us to do so.

We can have default values for listen port and for connect port but we should not "guess" other values in case these are not reachable.

If the user configures XUD to do so, It is OK to detect our IP external address (that may change due to the ISP, without the user involvement). There is no reason to auto-detect the port since this is not dynamic.

If reliable, we can try to verify the host:port XUD advertise.

LND and BTCD are working good for a large community. I see no reason to do something else.

Beside the external IP being changed (not in the user control) these are setup issues that should be debugged and resolved by the user. No need to resolve that for him.

[kilrau]

moved 80/443 part into https://github.com/ExchangeUnion/xud/issues/345

[moshababo]

@offerm

We can have default values for listen port and for connect port but we should not "guess" other values in case these are not reachable.

Which other values are you referring to?

[offerm]

443 and 80. (what about 8080 :-) )
Don't think we should try these ports as fallback. There is a high probability of these ports to be open but not related to xud.

[moshababo]

I'm not sure I understood your comment in the overall.

The point here is to alert the user in case his node is not reachable, assuming that he doesn't know about it.
You're saying that out detection wouldn't be reliable, or that we shouldn't bother to alert about it?

[kilrau]

You didn't understand my comment or @offerm s? I did back down with the alternative ports (for now) and shifted the discussion to a later stage. This issue is solely about
a) checking if my OWN externalIP+Port is reachable and
b) if not, alert as per https://github.com/ExchangeUnion/xud/issues/182#issuecomment-413043575

That's it. Simple issue :)

[moshababo]

I was referring to @offerm's comment

[offerm]

@moshababo I don't consider this as a big thing. This way or another.