ipseckey: 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/ipseckey - from package: hash-slinger

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

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