Lantronix LPS1-T EPS Reference Manual - Page 21

Reverse Telnet RTEL, LPR Support, TCP/IP Utilities and Commands

Page 21 highlights

Concepts TCP/IP The Server will respond to queries for unknown MIBs with a "not in MIB" error to the requesting host. RFC's 1065, 1066, and 1098 offer additional information on SNMP queries and the structure of the MIBs. See Set/Define SNMP on page 12-61 for more information about configuring MIB usage. Traps are sent to a host when an abnormal event occurs on the Server. The Server can generate limited forms of three SNMP traps. It will generate a Coldstart trap when it first boots, and a Linkup trap when the startupfile (if any) has been read from a host and normal operation commences. If a startupfile has been configured but the download fails, the Server will send an Authentication trap. In all three cases, the trap will be directed to the IP address of the Server's loadhost. The Server will not generate traps for any other cases. Note: To disable traps, define the Loadhost as "0.0.0.0" and reboot the server. See Set/ Define Server Loadhost on page 12-41 for syntax. The Server has a local SNMP security table to restrict or prevent unauthorized SNMP configuration. 2.6.4 Reverse Telnet (RTEL) When a server provides a service to a LAT host, the connection is often referred to as Reverse LAT. Reverse Telnet allows a UNIX host to initiate connections to the Server in much the same way. It is called Reverse Telnet because "normal" connections are logins from a server to a host. Your Server comes with special software to add RTEL functionality to your UNIX host. RTEL connections can be made through a back-end program for a printer, or through a named pipe. For example, you can print files from your UNIX host to a printer attached to the Server through your host's lp or lpr print system. Server services do not care what hosts are using them. Multiple jobs from any of the supported protocols can be queued simultaneously on any service. 2.6.5 LPR Support The Server and many UNIX systems implement the lpr (Berkeley remote printing) protocol, a protocol that makes it very easy to add print hosts to a system. To add the Server as a print host, add the Server's IP address to a host table and add the Server's service name as a print queue. No special host software or other configuration is needed. Server services can be accessed via the normal lpr commands on the host. Print jobs can be forwarded multiple "hops" in the network. If you only want one host to know about Server print queues, configure the other hosts to forward their print jobs to that host which will forward them to the Server for printing. Note: See Chapter 7, TCP/IP Host Setup, for more information. 2.6.6 TCP/IP Utilities and Commands The following commands have been added to help TCP/IP usability: Finger Displays users on local and remote hosts. The finger command by itself shows all users on the Server. If given with a parameter, such as user@host, it shows information regarding the named user on the specified host. The username can be omitted, in which case all the users on the remote host will be displayed. If the host cannot be reached or accessed, the finger command fails. 2-7

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Concepts
TCP/IP
2-
7
The Server will respond to queries for unknown MIBs with a “not in MIB” error to the requesting host.
RFC’s 1065, 1066, and 1098 offer additional information on SNMP queries and the structure of the MIBs.
See
Set/Define SNMP
on page 12-61 for more information about configuring MIB usage.
Traps
are sent to a host when an abnormal event occurs on the Server. The Server can generate limited
forms of three SNMP traps. It will generate a
Coldstart
trap when it first boots, and a
Linkup
trap when
the startupfile (if any) has been read from a host and normal operation commences. If a startupfile has been
configured but the download fails, the Server will send an
Authentication
trap. In all three cases, the trap
will be directed to the IP address of the Server’s loadhost. The Server will not generate traps for any other
cases.
Note:
To disable traps, define the Loadhost as “0.0.0.0” and reboot the server. See Set/
Define Server Loadhost on page 12-41 for syntax.
The Server has a local SNMP security table to restrict or prevent unauthorized SNMP configuration.
2.6.4
Reverse Telnet (RTEL)
When a server provides a service to a LAT host, the connection is often referred to as Reverse LAT. Reverse
Telnet allows a UNIX host to initiate connections to the Server in much the same way. It is called Reverse
Telnet because “normal” connections are logins from a server to a host.
Your Server comes with special software to add RTEL functionality to your UNIX host. RTEL connections
can be made through a back-end program for a printer, or through a named pipe. For example, you can print
files from your UNIX host to a printer attached to the Server through your host’s
lp
or
lpr
print system.
Server services do not care what hosts are using them. Multiple jobs from any of the supported protocols
can be queued simultaneously on any service.
2.6.5
LPR Support
The Server and many UNIX systems implement the
lpr
(Berkeley remote printing) protocol, a protocol that
makes it very easy to add print hosts to a system. To add the Server as a print host, add the Server’s IP
address to a host table and add the Server’s service name as a print queue. No special host software or other
configuration is needed. Server services can be accessed via the normal lpr commands on the host.
Print jobs can be forwarded multiple “hops” in the network. If you only want one host to know about Server
print queues, configure the other hosts to forward their print jobs to that host which will forward them to the
Server for printing.
Note:
See Chapter 7, TCP/IP Host Setup, for more information.
2.6.6
TCP/IP Utilities and Commands
The following commands have been added to help TCP/IP usability:
Finger
Displays users on local and remote hosts. The finger command by itself shows
all users on the Server. If given with a parameter, such as user@host, it shows
information regarding the named user on the specified host. The username can
be omitted, in which case all the users on the remote host will be displayed. If
the host cannot be reached or accessed, the finger command fails.