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Unformatted text preview: grees (which it doesn't
in line 13), the server would send a suboption to the client whenever the processing
of Control-S and Control-Q needs to switch between the client and server. (This is
similar to what we saw with the Rlogin 0x10 and 0x20 commands in Figure 26.4.)
As we said in our discussion of Rlogin, the interactive user obtains better response
to flow control when it's done by the client, not by the server.
6. LINEMODE is the real linemode that we mentioned in Section 26.4. All the
terminal character processing is done by the Telnet client (backspace, erase line,
etc.) and complete lines are sent to the server. We'll see an example of it later in this
section. This option is refused in line 14.
7. The ENVIRON option lets the client send environment variables to the server, as
defined in RFC 1408 [Borman 1993a]. "This can automatically propagate variables
in the user's environment on the client host to the server. The server refuses this
option in line 15. (An environment variable in Unix is often an uppercase name,
followed by an equals sign, followed by a string value, but this is only a
convention.) By default the BSD/386 Telnet client sends only the two variables file:///D|/Documents%20and%20Settings/bigini/Docum...ti/homenet2run/tcpip/tcp-ip-illustrated/telnet.htm (21 of 26) [12/09/2001 14.47.45] Chapter 26. Telnet and Rlogin: Remote Login DISPLAY and PRINTER, if they're defined and if the option is enabled. The Telnet
user can specify additional environment variables to be sent.
8. The STATUS option (RFC 859 [Postel and Reynolds 1983e]) lets one end ask the
other for its perception of the current status of the Telnet options. In this example
the client is asking the server to enable the option (DO). If the server agreed (which
it doesn't in line 16), the client could ask the server in a suboption to send its status.
9. This is the first response from the server. The server agrees to enable the terminal
type option. (Almost every Unix server supports this option.) The client, however,
cannot send its ter...
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This test prep was uploaded on 04/04/2014 for the course ECE EL5373 taught by Professor Guoyang during the Spring '12 term at NYU Poly.
- Spring '12