rvnamed: 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/rvnamed - from package: iptraf

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

On Debian possible default full paths are:

/usr/sbin/rvnamed - from package: iptraf

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

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