sctp_darn: 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/sctp_darn - from package: lksctp-tools

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

On Debian possible default full paths are:

/usr/bin/sctp_darn - from package: lksctp-tools

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

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