Upcoming EuroBSDCon OpenBSD talk A Packet's Journey Through the OpenBSD Network Stack by Alexander Bluhm
Upcoming EuroBSDCon OpenBSD talk A Packet's Journey Through the OpenBSD Network Stack by Alexander Bluhm
Upcoming EuroBSDCon OpenBSD talk A Packet's Journey Through the OpenBSD Network Stack by Alexander Bluhm
When debugging network issues, it is important to understand whencertain things happen. Tcpdump provides valuable insight, pftransforms packets, pseudo devices add features, and netstat countersshow action. The call graph of the functions within the kernel isthe base to comprehend the relation between these sources ofinformation.
The layering of kernel code in hardware drivers, pseudo devices,IP processing, forwarding and protocol layer is explained. Thekernel provides the socket interface to userland processes. Packetforwarding happens within the kernel. Bridge code uses certainshortcuts. pf is a swiss knife that can manipulate traffic inmultiple layers. IPsec has an independent interface that overridesrouting. Routing itself and neighbor discovery is a necessary stepthat has its tentacles everywhere. Checksum calculation can beperformed by hardware offloading.
By using examples with a single packets, their way through thekernel is shown. The possible branches, configuration options, andmeasurement output are put in correlation.
Tickets are still available and this talk will be streamed and recorded for later release.