Network hackers are always on the prowl to attack an organization's network. Although these attacks mostly take place at major financial institutions, government agencies and pharmaceutical companies, that does not mean that an organization that deals in any other business is free from the network hacker. A patient network hacker would not compromise the network servers during normal working hours. He will usually launch an attack between 9 p.m. and 6 a.m., reducing the likelihood of anyone knowing about the attack. This gives the network hacker more time to apply sniffers and backdoors on the network hosts without having to worry about the presence of system administrators.