ike-scan: 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/ike-scan - from package: ike-scan

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

On Debian possible default full paths are:

/usr/bin/ike-scan - from package: ike-scan

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

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