Consoles in the Forum Self-managed server room

Contents

These notes describe how to use the Lantronix SLC unit smslc00 in the Self-managed server room (in conjunction with the conserver software package and the School's LCFG infrastructure) to provide remote access to the console of a machine in that room.

Note: The assumption is that the machine in question has been configured so that its console has been redirected to its serial port. This configuration must - of course - be done by the owner of the machine in question. The serial interface of the machine should be configured to run at 9600,8,n,1.

1. Configuration

Note: All of the following configuration will be arranged by computing support, on request from the owner of the machine in question.

1.1 Cabling

The machine's serial port should be connected to the next available device port of the Lantronix SLC smslc00 using a standard TP cable. You must use the appropriate RJ45<->DB9F adaptor at the machine end to make this connection: the Lantronix part number for the required adaptor is 200.2070A.

Such adaptors are available in the Forum server room: we have some 'official' Lantronix adaptors (coloured grey, and labelled '200.2070A'), and also some adaptors which have been made in-house by our technicians: these are coloured green.

Note that, by default, all incoming serial connections on the SLC are expected to run at 9600,8,n,1. The use of different baud rates etc. is strongly discouraged, but, if necessary, can be accommodated by appropriate reconfiguration of the SLC's device port(s).

1.2 Setting LCFG resources

Edit the live header live/smconsole_server.h and add the target machine's name, and the UUN's of its authorised console user(s), to the appropriate resources.

Example:

The serial console of machine myserver has been cabled to device port 05 of the Lantronix SLC console server smslc00, and is to have three authorised console users, each of whom will have full read/write access to the console. Their UUNs are uun1 (a member of staff), uun2 and uun3 (two postgrads).

Add the following to live/smconsole_server.h:

  conserver.users_staff                   uun1
  conserver.users_postgrads               uun2 uun3

  ...[snip]...

  conserver.consolename_smslc00p05        myserver
  !conserver.crw_smslc00p05               mADD(uun1)
  !conserver.crw_smslc00p05               mADD(uun2)
  !conserver.crw_smslc00p05               mADD(uun3)

2. Using the console

Note: The console can be accessed as described below by all users nominated by the owner of the machine in question (all such users will have been appropriately configured as described in the preceding section), as well as by all School C(S)O's.

To access the console:

  1. ssh to the machine smconsoles.

  2. Issue the command

    console <target machine name>

    and authenticate using your usual DICE password *.

    (Note that the <target machine name> is the single word name of the machine, and not its fully-qualified domain name.)

  3. Once authenticated, proceed as described in the man page 'man -s1 console'.

    In particular, note that:

    1. The escape sequence for the console command has been configured as Ctrl-] Ctrl-].
    2. A SysRq break is sent to the target machine using the sequence Ctrl-] Ctrl-] l 0 (that's lower-case L, followed by a zero).
    3. A SysRq reboot command is sent to the target machine using the sequence Ctrl-] Ctrl-] l 0 b.
    4. A help page can be displayed within the console session by the sequence Ctrl-] Ctrl-] ?.
    5. The console session itself is terminated by the sequence Ctrl-] Ctrl-] . (that's a 'dot').

(* School C(S)O's - and only School C(S)O's ! - should use their specific conserver passwords to authenticate; all other users should use their usual DICE passwords.)

3. Further information

  1. Complete information on the console command can be found in the man page man -s1 console..
  2. General usage information about conserver can be found at the conserver website.

-- IanDurkacz - 28 Apr 2009

Topic revision: r7 - 25 May 2010 - 09:42:12 - IanDurkacz
 
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