The most important part IMHO is here https://github.com/freebsd/freebsd/tree/master/sys/netinet/tcp_stacks https://github.com/freebsd/freebsd/tree/master/sys/ne

The most important part IMHO is here https://github.com/freebsd/freebsd/tree/master/sys/netinet/tcp_stacks https://github.com/freebsd/freebsd/tree/master/sys/netinet/t.... The TLS sendfile piece is a bit specialized, mainly interesting if you are doing the exact same workload i.e. a CDN on UFS disks. I can say on some authority (I had all the relevant code at my last job) NF will give it to you if you ask and have a need/competence. The reason the TLS bits aren't upstream is that they aren't general purpose or "finished" yet. It relies on some third party code outside of src like boringssl and Intel's isa-l.