修改配置文件：vim /etc/apt/sources.list
官方源
deb-src http://http.kali.org/kali/ kali-rolling main non-free contrib
deb http://http.kali.org/kali kali-rolling main non-free contrib
中科大源
deb http://mirrors.utsc.edu.cn/kali kali-rolling main non-free contrib
阿里雲kali源
deb http://mirrors.aliyun.com/kali sana main non-free contrib
deb http://mirrors.aliyun.com/kali-security sana/updates main contrib non-free
清華更新源
deb http://mirrors.tuna.tsinghua.edu.cn/kali kali-rolling main non-free contrib
deb-src http://mirrors.tuna.tsinghua.edu.cn/kali kali-rolling main non-free contrib
直接去官網找更新源，如阿里雲https://developer.aliyun.com/mirror/
apt-get update ：同步 /etc/apt/sources.list 和 /etc/apt/sources.list.d 中列出的源的索引，這樣才能獲取到最新的軟件包。
apt-get upgrade：更新了apt的資源列表，沒有真正的對系統執行更新。如果需要，要使用apt-get upgrade來更新。
apt-get dist-upgrade：更新bai所有的軟件。
apt-get clean：把已安裝的軟件包的安裝包也刪除掉。