[tahoe-dev] Troubleshooting node connectivity

[Brian Warner]

Shawn Willden wrote:
> While checking my backups I've noticed a problem: two of the nodes in
> my friendnet aren't reachable by others. I'm pretty sure it's not a
> NAT/firewall issue, because those nodes ARE reachable by two other
> nodes.

> Of the four reliable nodes (two running on Lenny, two running on
> Ubuntu 9.10), the two Lenny boxes can connect to the two Ubuntu boxes,
> but the Ubuntu boxes can't connect to one another.

Remember that Tahoe nodes establish connections bidirectionally, and
that once the A->B connection is made, it can also be used B->A. So if
your two Ubuntu boxes are behind firewalls, then in fact maybe nobody
can establish a connection *to* them, but they can make outbound
connections to anyone else that isn't behind a firewall (i.e. everyone
but the other Ubuntu box). And what's happening is that the Ubuntu boxes
are actually initiating successful connections to the Lenny boxes rather
than the other way around.

The storage-server hostname/port that's advertised in the Introducer
announcement (tahoe.cfg:[node]tub.location) needs to be able to get
through to the port number that the server is actually listening on
(tahoe.cfg:[node]tub.port). The other tahoe nodes don't need to connect
to the webapi port, just the Tub's port.

I think that 'flogtool tail' will tell you when connections are
initiated and established.. there's a lot of debug-level logging noise
emitted during protocol negotiation. But what you might just try is to
telnet into the host/port that's advertised in the introducer. If you
can't make a connection, then neither will the tahoe node.

> The routers for both have them have been configured to forward the web
> interface port and the client port to the machines. I've verified
> connectivity to both of those ports in both cases, and the Lenny
> machines can connect to both nodes.

But that suggests that you've already tried that test, and succeeded in
getting through in the direction that's in question. Hrm.

puzzled,
 -Brian