[$] The return of nftables
Some ideas take longer than others to find their way into the mainline
kernel. The network firewalling mechanism known as "nftables" would
be a case in point. Much of this work was done in 2009; despite showing
a lot of promise at the time, the work languished for years afterward.
But, now, there would appear to be a critical mass of developers working on
nftables, and we may well see it merged in the relatively near future.