ip ddns update method dyndns
 HTTP
  add http://lll%40lll.ru:password@dynupdate.no-ip.com/nic/update?hostname=aaa.bbb.cc
 interval maximum 20 0 0 0
 interval minimum 0 23 0 0
!             
interface Dialer1
 ip ddns update hostname aaa.bbb.ccc
 ip ddns update dyndns host dynupdate.no-ip.com