alias lockdown {
  if (%lockdn == 1) { echo -a 3The lockdown is no longer in effect. | unset %lockdn }
  else { set %lockdn 1 | echo -a 4The network is now in lockdown. To end the lockdown retype this command.  }
}

on *:SNOTICE: {
  if ($5 == connecting && %lockdn == 1) { kill $9 A lockdown is currently in effect on the IRC network; we are not accepting any new connections. }
  else { }
}