I am trying to setup multiple "drones" using Net::SSH::Perl to send a command that creates the work directory, then Net::SCP to copy the files to the drone. The first connection works as intended. The second (a new SSH to the next drone in the list) apparently times out after a 5-10 minute wait. Using debug mode I see the same messages for success and failure - up to the connection closed message:

Setting up drone tux20.
tux-queen: Reading configuration data /home/queen/.ssh/config
tux-queen: Reading configuration data /etc/ssh_config
tux-queen: Connecting to tux20, port 22.
tux-queen: Remote version string: SSH-2.0-OpenSSH_4.3p2 Debian-8ubuntu
+1

tux-queen: Remote protocol version 2.0, remote software version OpenSS
+H_4.3p2 Debian-8ubuntu1
tux-queen: Net::SSH::Perl Version 1.30, protocol version 2.0.
tux-queen: No compat match: OpenSSH_4.3p2 Debian-8ubuntu1.
tux-queen: Connection established.
tux-queen: Sent key-exchange init (KEXINIT), wait response.
tux-queen: Algorithms, c->s: 3des-cbc hmac-sha1 none
tux-queen: Algorithms, s->c: 3des-cbc hmac-sha1 none
tux-queen: Entering Diffie-Hellman Group 1 key exchange.
tux-queen: Sent DH public key, waiting for reply.
tux-queen: Received host key, type 'ssh-dss'.
tux-queen: Host 'tux20' is known and matches the host key.
tux-queen: Computing shared secret key.
tux-queen: Verifying server signature.
tux-queen: Waiting for NEWKEYS message.
tux-queen: Enabling incoming encryption/MAC/compression.
tux-queen: Send NEWKEYS, enable outgoing encryption/MAC/compression.
tux-queen: Sending request for user-authentication service.
tux-queen: Service accepted: ssh-userauth.
tux-queen: Trying empty user-authentication request.
tux-queen: Authentication methods that can continue: publickey,passwor
+d.
tux-queen: Next method to try is publickey.
tux-queen: Trying pubkey authentication with key file '/home/queen/.ss
+h/id_dsa'
Connection closed by remote host. at /usr/local/share/perl/5.8.7/Net/S
+SH/Perl/AuthMgr.pm line 142
[download]

Here is the core of the code:

foreach $machine (@machine_name) {
   $cmd = "$drone_ssh";
   {
      local $ssh;
      my %params;
      $params{"protocol"}    = '2,1';
      $params{"debug"}    = '1';
      $ssh = Net::SSH::Perl->new( "$machine", %params );
      $ssh->login("$drone_user", %params);
      ( $stdout, $stderr, $exit ) = $ssh->cmd($cmd);
      undef $ssh;
   }

   if ( $exit == 0 ) {
      {
         # copy run files to drone
         local $scp;
         $scp = Net::SCP->new( "$machine", "$drone_user" );
         foreach $filename (@files) {
            chomp( $target = $filename );
            $scp->put( "$target", 
                       "$base_directory\/$work_directory\/" )
               || ( $scp->{errstr}
                 && print( $LF,
                         "ERROR: scp $target to $machine: $scp->{errst
+r}" )
            ); 
         }
         undef $scp;
      }
   }
[download]

I have tried this without the local $ssh , local $scp and undef $ssh and undef $scp commands, with the same results. Why can't I make SSH connections to multiple machines using Net::SSH::Perl?