net2kiss: command not found

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

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

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/sbin/net2kiss - from package: ax25-tools

You may install the required package with command apt-get install {package}

Error in other languages:
net2kiss: bevel nie gevind nie
net2kiss: comandă negăsită
net2kiss: comando não encontrado
net2kiss: commande introuvable
net2kiss: command not found
net2kiss: käsku ei ole
net2kiss: không tìm thấy lệnh
net2kiss: komanda nerasta
net2kiss: Kommando nicht gefunden.
net2kiss: kommandot finns inte
net2kiss: komut yok
net2kiss: nie znaleziono polecenia
net2kiss: níor aimsíodh an t-ordú
net2kiss: no se encontró la orden
net2kiss: no s'ha trobat l'ordre
net2kiss: opdracht niet gevonden
net2kiss: parancs nem található
net2kiss: perintah tidak ditemukan
net2kiss: príkaz nenájdený
net2kiss: příkaz nenalezen
net2kiss: команда не найдена
net2kiss: командата не е открита
net2kiss: 命令找不到
net2kiss: コマンドが見つかりません