kismet_client: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/kismet_client - from package: kismet

You may install the required package with command apt-get install {package}
Error in other languages:
kismet_client: bevel nie gevind nie
kismet_client: comandă negăsită
kismet_client: comando não encontrado
kismet_client: commande introuvable
kismet_client: command not found
kismet_client: käsku ei ole
kismet_client: không tìm thấy lệnh
kismet_client: komanda nerasta
kismet_client: Kommando nicht gefunden.
kismet_client: kommandot finns inte
kismet_client: komut yok
kismet_client: nie znaleziono polecenia
kismet_client: níor aimsíodh an t-ordú
kismet_client: no se encontró la orden
kismet_client: no s'ha trobat l'ordre
kismet_client: opdracht niet gevonden
kismet_client: parancs nem található
kismet_client: perintah tidak ditemukan
kismet_client: príkaz nenájdený
kismet_client: příkaz nenalezen
kismet_client: команда не найдена
kismet_client: командата не е открита
kismet_client: 命令找不到
kismet_client: コマンドが見つかりません