ncat: 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 CentOS possible default full paths are:

/usr/bin/ncat - from package: nmap

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/ncat - from package: nmap

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

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