The document discusses different components of corporate firewalls: Firewalls prevent unauthorized access to a company's network from outside networks like the Internet. They monitor data flowing in and out and intercept unjust access. FTP (File Transfer Protocol) allows sending and receiving files between machines remotely over the Internet. A bastion host is a hardened computer located outside the firewall that withstands attacks and typically hosts a single application like a proxy server. A proxy server acts as an intermediary between clients and other servers, evaluating requests according to filtering rules and sometimes altering or serving requests without contacting the actual server.

1. How Corporate Firewalls Work
● About Firewall
● About FTP
● About Bastion Host
● About Proxy Server

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

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

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

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