ipv6 random:
sudo sysctl -w net.inet6.ip6.use_tempaddr=1

TimeMachine:

http://hints.macworld.com/article.php?story=20090905212640957
http://www.kremalicious.com/2008/06/ubuntu-as-mac-file-server-and-time-machine-volume/

hdiutil create -size 500G -fs HFS+J -volname 'Time Machine Backups' -type SPARSEBUNDLE snowy.sparsebundle

cat com.apple.TimeMachine.MachineID.plist
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>com.apple.backupd.HostUUID</key>
    <string>YOURUUIDHERE</string>
</dict>
</plist>

defaults write com.apple.systempreferences TMShowUnsupportedNetworkVolumes 1