Week14 F
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Week14 F






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Week14 F Week14 F Document Transcript

  • How Corporate Firewalls Works Contents 1:What is a Firewall(1,2) 2:Screening Router(3) 3:Bastion Host(4) 4:The Place of The Bastion Host and The Function of An Exterior Screening Router(5,6)
  • What is a Firewall A firewall is a part of a computer system or network that is designed to block unauthorized access while permitting authorized communications. When someone on network inside the firewall wants to access the Internet, the request and data must go through an internal screening router that examines all the packets of data traveling in both directions between the network and the Internet.
  • Screening Router Based on the Information in the headers, the screening router allows certain packets to be sent or received, but blocks other packets. For example: ● It might not allow some services, such as rlogin, to be run. ~The router also might not allow packets to be sent to and from specific Internet locations because those locations have been found to be suspicious. Conceivably , a router could be set up to block every packet traveling between the Internet and the internal network except for email. System administrators set the rules for determining which packets to allow in and which ones to block. Quoted Image by:http://www.cs.wright.edu/~pmateti/InternetSecurity/Lect ures/PacketFilter/index.html
  • Bastion Host ● A bastion host is a special purpose computer on a network specifically designed and configured to withstand attacks. ○ Examples:web server, DNS server, FTP server... ● A bastion host in the firewall is the primary point of contact for connections coming in from the Internet for services. ○ For example: ■ receiving email, allowing access to the corporation's FTP site. ● Bastion host is a heavily protected server. ○ And can also be set up as proxy server. Reference: ● http://www.trust-us.ch/contrib/netzmafia/sicherheit/fw2.gif ● http://en.wikipedia.org/wiki/Bastion_host
  • The Place of The Bastion Host and The Function of An Exterior Screening Router ● The bastion host is not placed on the corporate network but in a perimeter network in the firewall. ● If the bastion host were on the normal corporate network, an intruder could conceivably gain access to every computer on the network and to all network services. ● An exterior screening router (also called an access router) screens packets between the Internet and the perimeter network. http://www.xbitlabs.com/articles/networking/display/edimax_3.ht ml
  • References Google http://www.google.co.jp Wikipedia http:ja.wikipedia.org/wiki