tcpKeepAlive, err := syscall.GetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_KEEPALIVE)
	if err != nil {
		return
	}
	tcpKeepAliveIdle, err := syscall.GetsockoptInt(fd, syscall.IPPROTO_TCP, syscall_TCP_KEEPIDLE)
	if err != nil {
		return
	}
	tcpKeepAliveInterval, err := syscall.GetsockoptInt(fd, syscall.IPPROTO_TCP, syscall_TCP_KEEPINTVL)
	if err != nil {
		return
	}

		tcpKeepAliveCount        int
	)
	if unix.SupportTCPKeepAliveIdleIntvlCNT() {
		tcpKeepAliveIdle, err = syscall.GetsockoptInt(fd, syscall.IPPROTO_TCP, syscall_TCP_KEEPIDLE)
		if err != nil {
			return
		}
		tcpKeepAliveIdleTime = time.Duration(tcpKeepAliveIdle) * time.Second

		tcpKeepAliveInterval, err = syscall.GetsockoptInt(fd, syscall.IPPROTO_TCP, syscall_TCP_KEEPINTVL)
		if err != nil {
			return
		}

			fd := int(fdPtr)

			_ = unix.SetsockoptInt(fd, unix.SOL_SOCKET, unix.SO_REUSEADDR, 1)

			_ = unix.SetsockoptInt(fd, unix.SOL_SOCKET, unix.SO_REUSEPORT, 1)

			// Enable custom socket send/recv buffers.
			if opts.SendBufSize > 0 {
				_ = unix.SetsockoptInt(fd, unix.SOL_SOCKET, unix.SO_SNDBUF, opts.SendBufSize)
			}

			if opts.RecvBufSize > 0 {
				_ = unix.SetsockoptInt(fd, unix.SOL_SOCKET, unix.SO_RCVBUF, opts.RecvBufSize)

	}

	if d == 0 {
		d = defaultTCPKeepAliveIdle
	} else if d < 0 {
		return nil
	}
	// The kernel expects seconds so round to next highest second.
	secs := int(roundDurationUp(d, time.Second))
	err := fd.pfd.SetsockoptInt(syscall.IPPROTO_TCP, sysTCP_KEEPIDLE, secs)
	runtime.KeepAlive(fd)
	return wrapSyscallError("setsockopt", err)
}

func setKeepAliveInterval(fd *netFD, d time.Duration) error {

	secs := int(roundDurationUp(d, time.Second))
	err := fd.pfd.SetsockoptInt(syscall.IPPROTO_TCP, syscall.TCP_KEEPINTVL, secs)
	runtime.KeepAlive(fd)
	return wrapSyscallError("setsockopt", err)
}

func setKeepAliveCount(fd *netFD, n int) error {
	if n == 0 {
		n = defaultTCPKeepAliveCount
	} else if n < 0 {
		return nil
	}

	err := fd.pfd.SetsockoptInt(syscall.IPPROTO_TCP, syscall.TCP_KEEPCNT, n)
	runtime.KeepAlive(fd)

		probes = probes[:1]
	}
	for i := range probes {
		s, err := sysSocket(syscall.AF_INET6, syscall.SOCK_STREAM, syscall.IPPROTO_TCP)
		if err != nil {
			continue
		}
		defer poll.CloseFunc(s)
		syscall.SetsockoptInt(s, syscall.IPPROTO_IPV6, syscall.IPV6_V6ONLY, probes[i].value)
		sa, err := probes[i].laddr.sockaddr(syscall.AF_INET6)
		if err != nil {
			continue
		}
		if err := syscall.Bind(s, sa); err != nil {
			continue
		}