Should use temporary IPv6 addresses for Ubuntu user?

(English) I am using Ubuntu 9.04 desktop and I notice that eth0 has an IPv6 address, which is generated from EUI-64 including MAC address. But it raises a privacy issue. Please refer to the followings:

• RFC 4941 Privacy Extensions for Stateless Address Autoconfiguration in IPv6
• MacユーザはIPv6を切るかnet.inet6.ip6.use_tempaddr=1の設定を(Japanese)

I look for the sysctl information and I find the "net.ipv6.conf.all.use_tempaddr" and its value is 0. But it didn't work. It is necessary to set net.ipv6.conf.eth0.use_tempaddr = 1. But I don't find how to disable IPv6 address which is based on EUI-64. Some Internet draft says that this extension could make hard for future defenses against DDoS attacks. I'll be looking for this issue.