Hi Tom, I found a test program for AF_KCM: https://gist.githubusercontent.com/peo3/fd0e266a3852d3422c08854aba96bff5/raw/98e02e120bd4b4bc5d499c4510e5879bb3a023d7/kcm-sample.c I don't suppose you have a version that compiles? It seems that the userland BPF API has changed. Thanks, David