The remote host is missing an update to freenet6 announced via advisory DSA 555-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20555-1

Simon Josefsson noticed that the tspc.conf configuration file in freenet6, a client to configure an IPv6 tunnel to freenet6.net, is set world readable. This file can contain the username and the password used to contact the IPv6 tunnelbroker freenet6.net. For the stable distribution (woody) this problem has been fixed in version 0.9.6-1woody2. For the unstable distribution (sid) this problem has been fixed in version 1.0-2.2. We recommend that you upgrade your freenet6 package.