kali用apt下载东西的时候往往会遇到下载速度慢和下载失败的情况，为什么会发生这个问题呢，因为kali默认的源是国外的，所以只要更换掉这个源就可以了！！
在命令行输入：
vim etc/apt/sourcecs.list 
#中科大
deb http://mirrors.ustc.edu.cn/kali kali-rolling main non-free contrib
deb-src http://mirrors.ustc.edu.cn/kali kali-rolling main non-free contrib#阿里云
deb http://mirrors.aliyun.com/kali kali-rolling main non-free contrib
deb-src http://mirrors.aliyun.com/kali kali-rolling main non-free contrib#清华大学
#deb http://mirrors.tuna.tsinghua.edu.cn/kali kali-rolling main contrib non-free
#deb-src https://mirrors.tuna.tsinghua.edu.cn/kali kali-rolling main contrib non-free#浙大
deb http://mirrors.zju.edu.cn/kali kali-rolling main contrib non-free
deb-src http://mirrors.zju.edu.cn/kali kali-rolling main contrib non-free#东软大学
deb http://mirrors.neusoft.edu.cn/kali kali-rolling/main non-free contrib
deb-src http://mirrors.neusoft.edu.cn/kali kali-rolling/main non-free contrib#官方源
#deb http://http.kali.org/kali kali-rolling main non-free contrib
#deb-src http://http.kali.org/kali kali-rolling main non-free contrib#重庆大学
deb http://http.kali.org/kali kali-rolling main non-free contrib
deb-src http://http.kali.org/kali kali-rolling main non-free contrib
