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Chapter 3
Internet Protocols
certain types of directory operations, like relocating into different ones. FTP
teams up with Telnet to transparently log you into the FTP server and then
provides for the transfer of files.
Accessing a host through FTP is only the first step, though. Users must
then be subjected to an authentication login that's probably secured with
passwords and usernames implemented by system administrators to
restrict access. But you can get around this somewhat by adopting the
username "anonymous"--though what you'll gain access to will be
limited.
Even when employed by users manually as a program, FTP's functions are
limited to listing and manipulating directories, typing file contents, and
copying files between hosts. It can't execute remote files as programs.
Trivial File Transfer Protocol (TFTP)
Trivial File Transfer Protocol (TFTP)
is the stripped-down, stock version of
FTP, but it's the protocol of choice if you know exactly what you want and
where to find it. It doesn't give you the abundance of functions that FTP
does, though. TFTP has no directory-browsing abilities; it can do nothing
but send and receive files. This compact little protocol also skimps in the
data department, sending much smaller blocks of data than FTP, and there's
no authentication as with FTP, so it's insecure. Few sites support it because
of the inherent security risks.
When are FTP and TFTP used?
If you need to give someone a large file or you need to get a large file from
someone, FTP is a nice choice. Smaller files (less than 5MB) can just be sent
via e-mail if you have the bandwidth of DSL or a cable modem. However,
most ISPs don't allow files of 5MB to be e-mailed, so FTP is an option you
should consider if you are in need of sending and receiving large files (who
isn't these days?). To do this, you will need to set up a FTP server on the
Internet so that the files can be shared.
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