eBPF - Calico
eBPF is a Linux kernel feature that allows fast yet safe mini-programs to be loaded into the kernel in order to customize its operation. eBPF stands for “extended Berkeley Packet Filter”. The Berkeley Packet Filter was an earlier, more specialized virtual machine that was tailored for filtering packets. Tools such as tcpdump use this “classic” BPF VM to select packets that should be sent to userspace for analysis. eBPF is a considerably extended version of BPF that is suitable for general purpose use inside the kernel. While the name has stuck, eBPF can be used for a lot more than just packet filtering. eBPF is a virtual machine embedded within the Linux kernel. It allows small programs to be loaded into the kernel, and attached to hooks, which are triggered when some event occurs. This allows the behaviour of the kernel to be (sometimes heavily) customised. While the eBPF virtual machine is the same for each type of hook, the capabilities of the hooks vary considerably...