Source: https://www.researchgate.net/profile/Boualem_Merabet/publication/326300884_Presentation_de_services_en_telecommunication_Configuration_et_gestion_de_reseaux_sous_GNULinux/links/5b44c6d20f7e9b1c7220fda0/Presentation-de-services-en-telecommunication-Configuration-et-gestion-de-reseaux-sous-GNULinux.pdf