nc.openbsd: 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:

/bin/nc.openbsd - from package: netcat-openbsd

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

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