The shill network manager in Chrom*OS automatically overwrites the Accept Router Advertisements preference to default even if forwarding.
Since Re6st machines act as routers, we do not want this to happen, hence Grandenet wil set it to Accept.
To avoid a race condition, however, we redirect all file write to the approrpriate preference file to go to /dev/null.
Adapted by https://lab.nexedi.com/nexedi/userhosts/