RTELNET(8) UNIX System V RTELNET(8)
NAME
rtelnet - Annex reverse TELNET daemon
SYNOPSIS
rtelnet [ -bdfhmrD ] annex port device-name
ARGUMENTS
-b requests that rtelnet negotiate TELNET binary mode when
communicating with the Annex. This is for devices like laser
printers which use binary data that might be scrambled by TELNET's
CR/LF conventions.
-d turns on socket-level debugging.
-f enables the connect on the fly mode. The -m switch should also be
used with this mode, to ensure that rtelnet will drop the
connection when the slave device is not in use.
-h tells rtelnet to send a reset port RPC to the Annex port when the
slave pseudo device is closed. This must be used in conjuction with
the -m switch. This uses the same NETADM protocol used by na. This
will currently only work on Annexes without an annex_password
parameter set.
-m tells rtelnet to momentarily drop the network connection to the
Annex port whenever the slave pseudo device is closed. This causes
the Annex to drop DTR, which can be used to cause a dial-out modem
to hang up when a program like tip exits.
-r directs rtelnet to remove the device device-name if it already
exists. Without -r, rtelnet will exit with an error message if
device-name already exists.
-D turns on verbose debugging output. Rtelnet does not fork off a
daemon in this case; instead, it displays TELNET option negotiation
and all received data on the terminal where rtelnet was started.
annex The hostname or Internet address (in standard Internet dot
separated notation) of the Annex.
port The serial port number on the Annex.
device-name
name of psuedo device to create (usually in the /dev directory).
DESCRIPTION
Rtelnet is a modified version of the 4BSD telnetd program. Its purpose
is to create a pseudo-tty device that is connected to an Annex serial
port. This allows UNIX programs such as tip and uucp to access serial
devices attached to Annex ports. Rtelnet works like a telnet daemon
program (telnetd) except in a reverse fashion. Instead of accepting
telnet connections from other network machines, rtelnet makes telnet
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RTELNET(8) UNIX System V RTELNET(8)
connections to Annex ports. Rtelnet creates a new file-like device (in
/dev) that programs can open and use like a normal tty.
Normally, rtelnet makes the connection to the Annex immediately. This
ties the Annex port to exactly one host. This is useful for dedicated
devices. On the otherhand, this will not interact correctly with a port
set to the adaptive mode, which would normally be used for a dial-
in/dial-out modem. Such a configuration should use the connect on the
fly option. In that case, rtelnet will not make the connection
immediately, but will instead wait until another process opens the slave
device. When that happens, rtelnet will attempt to make the network
connection. When the connection is up, data will flow as normal. If the
connection cannot be made, rtelnet will try again using an exponential
backoff.
Rtelnet should run as-is on any 4BSD-based system. To run on other
systems may require some code modification. In particular, some systems
name their psuedo-terminals differently. The source code has rudimentary
support for some such systems.
Example usage:
A dial-out modem is attached to port 15 of an Annex named "modem-
annex". To enable its use via tip on a 4BSD host:
1. Configure port 15 using na to:
"control_lines: modem_control" "
mode: slave"
2. Start up rtelnet to create the pseudo-device:
rtelnet -rbm modem-annex 15 /dev/modem1
Normally, this would be added to the system startup file
(/etc/rc).
3. Create new system definition in /etc/remote specifying
/dev/modem1 as the device.
FILES
/dev/pty[p-s][0-9a-f] default list of master pseudo-terminals
/dev/tty[p-s][0-9a-f] default list of slave pseudo-terminals
SEE ALSO
Annex Network Administrator's Guide
DIAGNOSTICS
Messages should be self-explanatory.
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