1. su -
    3. cp /etc/apt/sources.list /etc/apt/sources.list.bak
    5. nano /etc/apt/sources.list
    7. deb http://mirrors.tuna.tsinghua.edu.cn/debian/ stretch main contrib non-free
    8. # deb-src https://mirrors.tuna.tsinghua.edu.cn/debian/ stretch main contrib non-free
    9. deb http://mirrors.tuna.tsinghua.edu.cn/debian/ stretch-updates main contrib non-free
    10. # deb-src https://mirrors.tuna.tsinghua.edu.cn/debian/ stretch-updates main contrib non-free
    11. deb http://mirrors.tuna.tsinghua.edu.cn/debian/ stretch-backports main contrib non-free
    12. # deb-src https://mirrors.tuna.tsinghua.edu.cn/debian/ stretch-backports main contrib non-free
    13. deb http://mirrors.tuna.tsinghua.edu.cn/debian-security stretch/updates main contrib non-free
    14. # deb-src https://mirrors.tuna.tsinghua.edu.cn/debian-security stretch/updates main contrib non-free
    16. apt update
    17. apt upgrade
    18. apt install firmware-realtek
    20. apt install apt-transport-https
    22. rm /etc/apt/sources.list
    23. nano /etc/apt/sources.list
    25. deb https://mirrors.tuna.tsinghua.edu.cn/debian/ stretch main contrib non-free
    26. # deb-src https://mirrors.tuna.tsinghua.edu.cn/debian/ stretch main contrib non-free
    27. deb https://mirrors.tuna.tsinghua.edu.cn/debian/ stretch-updates main contrib non-free
    28. # deb-src https://mirrors.tuna.tsinghua.edu.cn/debian/ stretch-updates main contrib non-free
    29. deb https://mirrors.tuna.tsinghua.edu.cn/debian/ stretch-backports main contrib non-free
    30. # deb-src https://mirrors.tuna.tsinghua.edu.cn/debian/ stretch-backports main contrib non-free
    31. deb https://mirrors.tuna.tsinghua.edu.cn/debian-security stretch/updates main contrib non-free
    32. # deb-src https://mirrors.tuna.tsinghua.edu.cn/debian-security stretch/updates main contrib non-free