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000034_news@columbia.edu _Sun Mar 18 12:51:33 2001.msg
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From: fdc@columbia.edu (Frank da Cruz)
Subject: Re: Kermit Protocol basic questions
Date: 18 Mar 2001 17:47:37 GMT
Organization: Columbia University
Message-ID: <992sbp$5ve$1@newsmaster.cc.columbia.edu>
To: kermit.misc@columbia.edu
In article <3ab4edcb$1@news.iprimus.com.au>,
--abc-- <ima_devo@hotmail.com> wrote:
: I am currently doing a comparison of the Kermit and FTP protocols and have
: some questions:
:
: 1) Does Kermits use of a single multiplexed channel have implications for
: simultaneous transfer of commands while data transfer is in progress? (ie.
: In FTP there is the 2 channels available)
:
Kermit's scheme is simpler. Packets are used at the application level,
which include function-code fields ("commands"). In other words, each message
includes a command, and possibly also contents (e.g. file name, file
attributes, file data). The fact that there is only a single connection
removes all the difficulties with firewalls, active-vs-passive mode, etc.
: 2) Is the error recovery/Restart functionality available regardless of the
: mode of transfer? (In FTP crash recovery not avaialble using stream mode).
:
Recovery/restart is available only for binary-mode transfers. A scheme was
worked out for text mode, but it's quite complex given the fact that it would
have to work with every known file system and record format, including
record-oriented file systems as on IBM mainframes. So far it has not been
implemented, since there is little demand for it.
: 3) When using FTP, user may set up a connection between 2 other
: servers/machines, and use the users host to control the session. Is this
: capability available in Kermit?
:
No.
: Also, if u feel OK about some offtopic FTP questions :) :
:
: 1) Does FTP encrypt the login info for start of session, or are plain text
: passwords sent? Or does the TELNET client encrypt the login info?
:
Security is an option for FTP, Telnet, and Kermit. Secure servers and
clients are available for all three:
http://www.columbia.edu/kermit/telnetd.html
Incidentally, there are a lots of other axes along which you can compare
FTP and Kermit, including (to name a few):
. Handling of file attribute (date-time, size, permissions, etc)
. Automatic per-file text/binary mode switching
. Recursive directory-tree traversal
. Character-set conversion capabilities
. Automation features built into the client/server protocol
. Flexible filename collisions options, including update
As you might know, we have added FTP protocol to the new Kermit releases,
in a way that brings many of these features to FTP for the first time,
despite the fact that the FTP protocol is not designed to support them:
http://www.columbia.edu/kermit/ftpclient.html
- Frank