From the pcap-filter(7) manpage:
"Note that tcp, udp and other upper-layer protocol types only apply to IPv4, not IPv6 (this will be fixed in the future). "
Sometimes reading posts about BPF makes me think I'm the only one still using it to filter packets.
Cilium  is a great example of how the new capabilities of BPF can be used for more complex packet filtering, such as understanding higher level protocols.
Better Performance Finger-counting
Better Party Firecracker
Build Pretty Funnels
- Developers and system engineers: will add the BCC and bpftrace tools to their toolkit for analyzing issues, but they won't necessarily need to develop new ones themselves (so long as someone at the company can, as needed). The book targets this (large) audience by covering over 150 tools.
- Some developers will use the BPF tracers like bpftrace as a primary debugging tool as it's the best available for their language (eg, user and kernel C and C++); other mature runtimes may already have a tracer that developers are already using, making bpftrace a secondary debugging tool for digging deeper. In that case, you may find there is one or two people on a development team who learn bpftrace and deal with the deeper debugging, whereas others get by with their primary tracer. The book targets these audiences too, by explaining bpftrace programming and including many examples.
- There's another smaller audience where there'll be BPF demand that is not the focus of the book: custom BPF products. In the past, a monitoring/security company might sell you a loadable kernel module to do their thing; in the future, those should all become BPF programs (where possible), which are safer to run. There will also be new applications made possible by BPF. Some of these products will be bpftrace/BCC-based, and the book will be helpful. So I'd expect to see some demand for these BPF skills too, although it's a much narrower audience than the others. It'll be companies trying to hire BPF programmers to migrate their kernel modules to. Some companies already sell such BPF things (Cilium, Sysdig).
Seriously, its a (humorous) vote of confidence in Brendan's work.
Pro-tip: You can get free access to Safari by becoming a member of the ACM.
Oreilly only sells subscriptions to oreilly now (no epub purchases) and then redirects you to the DRM'ed amazon mobi or whatever.
I'd love to paypal you from your website for these type of things.
The Oreilly subscription is $39 a month btw...
ACM membership for something useful.