for my $box (@servers) {
  my $ssh = Net::OpenSSH->new($box,
                              user => $user,
                              password => $password);
  if ($ssh->error) {
    warn "unable to connect to $box";
    next;
  }
  for my $certfile (@certfiles) {
     my $output = $ssh->capture('openssl', 'x509', '-in',
                                "/etc/pki/tls/$certfile",
                                '-noout', '-subject',
                                '-hash', '-enddate');
     unless ($output =~ /notAfter=(\S+)/) {
        warn "expiration data not found in $box:$certfile"
        next;
     }

     my $notAfter = $1;

    ...
  }
}