A firewall is a system that prevents unauthorized access to a company's computer network from the outside. It monitors data flowing in and out and intercepts unjust access. A bastion host is a specially hardened computer located in the DMZ or outside the firewall that hosts a single application like a proxy server and has all other services removed or limited. A proxy server acts as an intermediary for requests from clients to external servers by evaluating requests according to filtering rules and optionally altering requests or responses.

1. How Corporate Firewalls Work
About Firewall
About FTP
About Bastion Host
About Proxy Server
Group B
How Corporate Firewalls Work – p.1/6

2. About Firewall
• system to prevent from it being invaded a
computer network in the organization with the
firewall by the outside. In addition, the computer
which such a system was incorporated in. Of the
third person invades it through outside networks
such as the Internet in the networks such as
companies, and data or an underlook the
destruction of the program being performed
watch data drifting to the border with the outside
so that there is not it, and it is necessary for the
detection to intercept unjust access. A system
realizing such a function is a firewall.
How Corporate Firewalls Work – p.2/6

3. About FTP
• The FTP is abbreviation of File Transfer Protocol
(a file transfer protocol) and becomes "the
file-transfer protocol" when I translate it into
Japanese. When it says intelligibly, it is long and
sends a file into a machine in the remote place
from a machine in one’s very front, and it is
structure far-off, to copy a file from a machine in
the remote place in the reverse. When I thought
that it would make one’s homepage that a general
Internet user employed being aware of FTP.
When I employ a modem or TA (a terminal
adaptor), and a general person connected to the
Internet makes one’s homepage with dial-up
connection.
How Corporate Firewalls Work – p.3/6

4. About Bastion Host
• A bastion host is a special purpose computer on a
network specifically designed and configured to
withstand attacks. The computer generally hosts
a single application, for example a proxy server,
and all other services are removed or limited to
reduce the threat to the computer. It is hardened
in this manner primarily due to its location and
purpose, which is either on the outside of the
firewall or in the DMZ and usually involves
access from untrusted networks or computers.
How Corporate Firewalls Work – p.4/6

5. About Proxy Server
• Proxy server is a server that acts as a go-between
for requests from clients seeking resources from
other servers Proxy server evaluates the request
according to its filtering rules Proxy server may
optionally alter the client’s request or the server’s
response, and sometimes it may serve the request
without contacting the specified server.
How Corporate Firewalls Work – p.5/6

6. Reference
• http://ja.wikipedia.org/wiki/Wiki
• http://chiebukuro.yahoo.co.jp/
• http://d.hatena.ne.jp/
• http://e-words.jp/
How Corporate Firewalls Work – p.6/6