sserver: 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/sbin/sserver - from package: krb5-devel
/usr/sbin/sserver - from package: krb5-server

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

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