Failed to dial through 0 known relay hosts

[hot3246624]

when i follow examplex-echo，in the 2nd terminal, i got the error: 2018/10/29 17:00:06 I am /p2p-circuit/ipfs/QmSNfGzsTDf7RDUtXiZSbmyEqz5tawrtkn7DrQ5GxeYNUM 2018/10/29 17:00:06 Now run "./echo -l 10002 -d /p2p-circuit/ipfs/QmSNfGzsTDf7RDUtXiZSbmyEqz5tawrtkn7DrQ5GxeYNUM -secio" on a different terminal 2018/10/29 17:00:06 opening stream 17:00:06.157 INFO swarm2: got error on dial to /p2p-circuit: <peer.ID QmxeYNUM> --> <peer.ID QmkzqPAp> dial attempt failed: Failed to dial through 0 known relay hosts swarm_dial.go:382 2018/10/29 17:00:06 dial attempt failed: <peer.ID QmxeYNUM> --> <peer.ID QmkzqPAp> dial attempt failed: Failed to dial through 0 known relay hosts

[vyzo]

That's because of a recent change in libp2p, which enables relay by default. The code is faulty and blindly uses the first address, which happens to be a relay address.

Possible solutions:

• pass libp2p.DisableRelay() to libp2p.New to turn off relay
• fix the code to be more clever about the use of addresses and don't try to dial the relay address.

edit: the simplest solution is to print all addrs in the I am ... part, not just the first address.

[hot3246624]

That's because of a recent change in libp2p, which enables relay by default. The code is faulty and blindly uses the first address, which happens to be a relay address.

Possible solutions:

• pass libp2p.DisableRelay() to libp2p.New to turn off relay
• fix the code to be more clever about the use of addresses and don't try to dial the relay address.

edit: the simplest solution is to print all addrs in the I am ... part, not just the first address.

it is not ok for me, when i dial other address such as 127.0.10.1, the error is: 19:53:38.817 WARNI swarm2: listen on /ip4/127.0.10.1/tcp/10000 failed: listen tcp4 127.0.10.1:10000: bind: can't assign requested address swarm_listen.go:25 19:53:38.817 WARNI swarm2: swarm listener accept error: process closing swarm_listen.go:77 2018/10/29 19:53:38 failed to listen on any addresses: [listen tcp4 127.0.10.1:10000: bind: can't assign requested address]

when i pass disableRelay() after libp2p.new, there is nothing change. And i cannot understand the the last word。

[cchx0000]

pass libp2p.DisableRelay() to libp2p.New to turn off relay

this indeed worked as I added opts = append(opts, libp2p.DisableRelay()) Thank you @vyzo

[stefanhans]

For me, this does the trick:

// Range over the addresses to find the first non relay address
for _, addr := range basicHost.Addrs() {
  if strings.SplitN(addr.String(), "/", 3)[1] != "p2p-circuit" {

    // Now we can build a full multiaddress to reach this host
    // by encapsulating both addresses:
      fullAddr := addr.Encapsulate(hostAddr)
      log.Printf("I am %s\n", fullAddr)
      if secio {
        log.Printf("Now run \"./echo -l %d -d %s -secio\" on a different terminal\n", 
                    listenPort+1, fullAddr)
      } else {
        log.Printf("Now run \"./echo -l %d -d %s\" on a different terminal\n", 
                    listenPort+1, fullAddr)
      }
    }
  }

Is it a realistic scenario to have a relay and not to use it?

Cheers, Stefan