/usr/include/x86_64-linux-musl/net/ is in musl-dev 0.9.15-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/x86_64-linux-musl/net/ethernet.h
/usr/include/x86_64-linux-musl/net/if.h
/usr/include/x86_64-linux-musl/net/if_arp.h
/usr/include/x86_64-linux-musl/net/route.h
/usr/include/x86_64-linux-musl/netinet/ether.h
/usr/include/x86_64-linux-musl/netinet/icmp6.h
/usr/include/x86_64-linux-musl/netinet/if_ether.h
/usr/include/x86_64-linux-musl/netinet/igmp.h
/usr/include/x86_64-linux-musl/netinet/in.h
/usr/include/x86_64-linux-musl/netinet/in_systm.h
/usr/include/x86_64-linux-musl/netinet/ip.h
/usr/include/x86_64-linux-musl/netinet/ip6.h
/usr/include/x86_64-linux-musl/netinet/ip_icmp.h
/usr/include/x86_64-linux-musl/netinet/tcp.h
/usr/include/x86_64-linux-musl/netinet/udp.h
/usr/include/x86_64-linux-musl/netpacket/packet.h