[Openswan Users] Dynamic IP change - Reestablish tunnel

[Michael Thalmann]

I am using the following setup:

Subnet (192.168.101.0/24)
  |
Openswan Gateway (DynDNS home / 192.168.101.1)
  |
Internet 
  |
Astaro Gateway (DynDNS office / 192.168.100.1)
  |
Subnet (192.168.100.0/24)

When Home gets a new IP, after a few minutes the tunnel is reestablished 
automatically. But when the remote endpoint (Astaro) gets a new IP,  Home
tries the old IP forever. It seems that it resolves the dynamic DNS 
office.gotdns.org once at startup and then never checks that again. I have 
thought of using the leftupdown script to check for an IP change of the 
remote endpoint and then restart ipsec.
Has anybody solved it that way or is there a more elegant solution?
ipsec.conf is as follows:

conn astaro
	esp=aes,3des
	keyingtries=0
        leftid=@home.gotdns.org
        left=192.168.101.1
        leftsubnet=192.168.101.0/255.255.255.0
        leftnexthop=192.168.101.254
        leftcert=/etc/ipsec.d/certs/astaro_home_cert.pem
	rightid=@office.gotdns.org
        right=office.gotdns.org
        rightsubnet=192.168.100.0/255.255.255.0
        pfs=yes
        authby=rsasig
        auto=start
	compress=yes


Thanks in advance for any advice.