iptab: 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/iptab - from package: perl-Net-IP

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

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