code: func applyListenIP(ip net.IP, cfg *service.Config) {
  	listeningAddresses := []*utils.NetAddr{
  		&cfg.Auth.SSHAddr,
  		&cfg.Auth.SSHAddr,
  		&cfg.Proxy.SSHAddr,
  		&cfg.Proxy.WebAddr,
  		&cfg.SSH.Addr,
  		&cfg.Proxy.ReverseTunnelListenAddr,
  	}
  	for _, addr := range listeningAddresses {
  		replaceHost(addr, ip.String())
  	}
  }
docs: // applyListenIP replaces all 'listen addr' settings for all services with
  // a given IP