Information Technology Reference
In-Depth Information
network traffic and providing a convenient and reliable environ
ment. The analysis becomes more complicated, however, if other
users want access to the same file at the same time, and we consider
this issue next.
Some uses of file sharing already have been implied through our
example involving Karen, Steve, Ella and their group project. Let's
look at those examples again and expand them with details and
variations.
Sharing with FTP: One way to share files is to make them avail
able on a common server, telling the file server that others are al
lowed to read the specified file. Users then utilize FTP to make their
own copies. When you post a file to the file server using FTP, it can
be accessed only by those who have permission. Thus, the first part
of any FTP session requires use of a user name and password. As
with many computer systems, files involving FTP are organized by
account, and anyone who has an account on the file server automat
ically can access the information related to that account. This is be
cause some FTP commands allow moving through a file system
from directory to directory, as long as owners have given permis
sion for such browsing. Thus, once someone has logged in to the
server using FTP, they could find your file (assuming the permission
and directory structure were appropriately configured) and copy the
file to their account.
Alternatively, Karen, Steven, and Ella could agree to place their
common file within an account with user name “anonymous”; this
approach involves the notion of “
anonymous FTP
.” In this ap
proach, a file server may have a special account, called “anony
mous,” and this account has a special directory for publicly avail
able files. Within this framework, users can run FTP and log in with
the user name “anonymous.” Often they provide their email ad
dresses or their user names on their client machine as their pass
word. Once logged in, access to files is limited to this special direc
tory and its subdirectories. If you have placed a copy of a file in this
area, then others will be able to use anonymous FTP to make copies
of your file. Karen, for example, could place a copy of her draft into
the anonymous FTP folder and anyone could access it, even people
who were not privy to general access to her school's network. Steve
