References: golang.org/x/sys/unix.TUN_F

const golang.org/x/sys/unix.TUN_F_CSUM

one use

	golang.org/x/sys/unix (current package)
		ztypes_linux.go#L6211: 	TUN_F_CSUM    = 0x1

The pages are generated with Golds v0.7.6. (GOOS=linux GOARCH=amd64)