my %connecting = map { $_ => 1 } @hosts;
while (1) {
  for my $host (keys %connecting) {
    my $ssh = $ssh{$host};
    if ($ssh->wait_for_master(1)) {
      delete $connecting{$host};
    }
    elsif ($ssh->error) {
      # handle connection error
      delete $connecting{$host};
    }
  }
  last unless %connecting; 
  select (undef, undef, undef, 0.05);
}
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@Salva

Thank you. So far, it looks like OpenSSH+Telnet will do what we need it to, although I am having to make some adjustments for the use of Telnet.

BTW, it would be nice (i.e. enhancement request) if $ssh->error provided a message that could differentiate between password, connect, and timeout failures: I get "unable to establish master SSH connection: bad password or master process exited unexpectedly" for authentication, for connect (socket not open), and for timeout errors. I need to be able to differentiate (that was pretty easy to do with Net::SSH2). Unless you have a better test, it looks like I'll need to try a socket connect before the opens to differentiate.

The connection and authentication phases are carried out by the OpenSSH client and it doesn't pass the cause of the failure back to the module.

An easy to implement workaround is to redirect the output of the master ssh process to a file and then, to retrieve it when something goes wrong.

my $ssh = Net::OpenSSH->new($host, master_stderr_file => "/tmp/ssh-std
+err-$host", master_opts => ['-v'], ...);
[download]