administrator as a critical strong point in the network security. Generally, bastion hosts will have some degree of extra attention paid to their security, may undergo regular audits, and may have modified software. Bastion Λհ͞ͳ͍ͱϓϥΠϕʔτʹ৵ೖͰ͖ͳ͍ɻ Ref: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.31.6790&rep=rep1&type=pdf discussing firewalls in 1990 by Marcus J. Ranum