$ wget -O - https://www.kismetwireless.net/repos/kismet-release.gpg.key | sudo apt-key add -
$ echo 'deb https://www.kismetwireless.net/repos/apt/release/bullseye bullseye main' | sudo tee /etc/apt/sources.list.d/kismet.list
$ sudo apt update
$ sudo apt install kismet