silkworm: unexpected termination when STUN server cannot be resolved

[canepat]

Running Silkworm on some machine behind strict firewall rules may lead to this unexpected termination to happen if Google STUN server (stun.l.google.com) default port (19302) is not open:

  INFO [12-23|18:32:57.658 UTC] Silkworm                                 version=master0.1.0-dev+commit.b0ce84b9 build=linux-x86_64 release compiler=gnu 11.4.0 
...
  INFO [12-23|18:32:57.789 UTC] Silkworm is now running
  INFO [12-23|18:32:57.789 UTC] SnapshotSync: downloading missing snapshots if needed
  INFO [12-23|18:32:57.789 UTC] SnapshotSync: download started: [0/462]
  CRIT [12-23|18:33:03.511 UTC] Unrecoverable failure: stun_ip_resolver: no response from the STUN server

We could try to detect such condition as accurately as possible and suggest to enable the command-line option --nat extip:<public_ip_address>.