每当我尝试aircrack-ng在终端中安装时，都会出现以下错误：
Package aircrack-ng is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
However the following packages replace it:
iw
E: Package 'aircrack-ng' has no installation candidate"
我是 Ubuntu 的新手，所以不知道该怎么做。