This tool is intended for (but not limited to) cluster administration where the same configuration or commands must be run on each node within the cluster. Performing these commands all at once via this tool ensures all nodes are kept in sync.

Connections are opened via ssh so a correctly installed and configured ssh installation is required. If, however, the program is called by ``crsh'' then the rsh protocol is used (and the communications channel is insecure).

Extra caution should be taken when editing system files such as /etc/inet/hosts as lines may not necessarily be in the same order. Assuming line 5 is the same across all servers and modifying that is dangerous. Better to search for the specific line to be changed and double-check before changes are committed.

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The dotted line on any sub-menu is a tear-off, i.e. click on it and the sub-menu is turned into its own window.

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Unchecking a hostname on the Hosts sub-menu will unplug the host from the cluster control window, so any text typed into the console is not sent to that host. Re-selecting it will plug it back in.

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If the code is called as crsh instead of cssh (i.e. a symlink called crsh points to the cssh file or the file is renamed) rsh is used as the communications protocol instead of ssh.

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Starting the utility will be much faster with a configuration file (as this prevents searching for required files). Generate one containing all default entries with:

"cssh -u > $HOME/.csshrc"

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When using cssh on a large number of systems to connect back to a single system (e.g. you issue a command to the cluster to scp a file from a given location) and when these connections require authentication (i.e. you are going to authenticate with a password), the sshd daemon at that location may refuse connects after the number specified by MaxStartups in sshd_config is exceeded. (If this value is not set, it defaults to 10.) This is expected behavior; sshd uses this mechanism to prevent DoS attacks from unauthenticated sources. Please tune sshd_config and reload the SSH daemon, or consider using the ~/.ssh/authorized_keys mechanism for authentication if you encounter this problem.

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If client windows fail to open, try running ``cssh -d <single host name>''. This will output a command to run which will test the method used by cssh to open client windows. If you copy-and-paste this command into a window and it fails, this is the issue. It is most likely due to the ``-xrm'' option which enables ``AllowSendEvents'' in the terminal. Some terminal do not require this option, other terminals have another method for enabling it. See your terminal documention for further information.

-h|-?

Show basic help text, and exit

-H

Show full help test (the man page), and exit

-v

Show version information and exit

-d

Enable basic debugging mode (can be combined with -D)

-D

Enable extended debugging mode (can be combined with -d)

-q|-Q

Enable|Disable automatically quiting after the last client window has closed (overriding the config file)

-u

Output configuration in the format used by the $HOME/.csshrc file

-g|-G

Enable|Disable window tiling (overriding the config file)

-c <file>

Use supplied file as additional cluster file (see also ``FILES'')

-l $LOGNAME

Specify the default username to use for connections (if different from the currently logged in user). NOTE: will be overridden by <user>@<host>

-T CSSH

Specify the initial part of the title used

Specify the initial part of the title used in the console and client windows

-o -x -o ConnectTimeout=10 - for ssh connections

-o - for rsh connections

Specify arguments to be passed to ssh or rsh when making the connection.

NOTE: any ``generic'' change to the method (i.e. specifying the ssh port to use) should be done in the medium's own config file (see ssh_config and $HOME/.ssh/config).

-t

Specify arguments to be passed to terminals being used

-i

Ignore errors from unresolvable host names (i.e. because the name is an alias within an ssh config file or similar) (see also ``ignore_host_errors'' in ``FILES'')

-e [user@]<hostname>[:port]

Display and evaluate the terminal and connection arguments so display any potential errors. The <hostname> is required to aid the evaluation.

[user@]<hostname>[:port] ...

Open an xterm to the given hostname and connect to the administration console. An optional port number can be used if sshd is not listening on standard port (e.g not listening on port 22) and ssh_config cannot be used.

<tag> ...

Open a series of xterms defined by <tag> within either /etc/clusters or $HOME/.csshrc (see ``FILES'').

Control-q

Quit the program and close all connections and windows

Control-+

Open the Add Host dialogue box

Alt-n

Paste in the correct client name to all clients, i.e.

"scp /etc/hosts server:files/<Alt-n>.hosts"

would replace the <Alt-n> with the client's name in all the client windows

Alt-r

Retile all the client windows

/etc/clusters

This file contains a list of tags to server names mappings. When any name is used on the command line it is checked to see if it is a tag in /etc/clusters (or the .csshrc file, or any additional cluster file specified by -c). If it is a tag, then the tag is replaced with the list of servers from the file. The file is formated as follows:

<tag> [user@]<server> [user@]<server> [...]

i.e.

 # List of servers in live
 live admin1@server1 admin2@server2 server3 server4

All standard comments and blank lines are ignored. Tags may be nested, but be aware of recursive tags.

Clusters may also be specified within the user's .csshrc file, as documented below.

/etc/csshrc & $HOME/.csshrc

This file contains configuration overrides - the defaults are as marked. Default options are overwritten first by the global file, and then by the user file.

always_tile = yes

Setting to anything other than "yes" does not perform window tiling (see also -G).

auto_quit = yes

Automatically quit after the last client window closes. Set to anything other than ``yes'' to disable. Can be overridden by "-Q" on the command line.

comms = ssh

Sets the default communication method (initially taken from the name of program, but can be overridden here).

clusters = <blank>

Define a number of cluster tags in addition to (or to replace) tags defined in the /etc/clusters file. The format is:

 clusters = <tag1> <tag2> <tag3>
 <tag1> = host1 host2 host3
 <tag2> = user@host4 user@host5 host6
 <tag3> = <tag1> <tag2>

As with the /etc/clusters file, be sure not to create recursivly nested tags.

console_position = <null>

Set the initial position of the console - if empty then let the window manager decide. Format is '+<x>+<y>', i.e. '+0+0' is top left hand corner of the screen, '+0-70' is bottom left hand side of screen (more or less).

ssh_args = -x -o ConnectTimeout=10

rsh_args = <blank>

Sets any arguments to be used with the communication method (defaults to ssh arguments).

NOTE: The given defaults are based on OpenSSH, not commercial ssh software.

NOTE: Any ``generic'' change to the method (i.e. specifying the ssh port to use) should be done in the medium's own config file (see ssh_config and $HOME/.ssh/config).

ignore_host_errors = no

If set to ``yes'', ignore errors from host names that cannot be resolved and attempt to connect anyway (i.e. because they are aliased in an ssh config file) - see also ``-i''

key_addhost = Control-plus

Default key sequence to open AddHost menu. See below notes on shortcuts.

key_clientname = Alt-n

Default key sequence to send cssh client names to client. See below notes on shortcuts.

key_quit = Control-q

Default key sequence to quit the program (will terminate all open windows). See below notes on shortcuts.

key_retilehosts = Alt-r

Default key sequence to retile host windows. See below notes on shortcuts.

key_paste = Control-v

Default key sequence to paste text into the console window. See below notes on shortcuts.

mouse_paste = Button-2 (middle mouse button)

Default key sequence to paste text into the console window using the mouse. See below notes on shortcuts.

screen_reserve_top = 25

screen_reserve_bottom = 30

screen_reserve_left = 0

screen_reserve_right = 0

Number of pixels from the screen side to reserve when calculating screen geometry for tiling. Setting this to something like 50 will help keep cssh from positioning windows over your window manager's menu bar if it draws one at that side of the screen.

ssh = /path/to/ssh

rsh = /path/to/rsh

Depending on the value of comms, set the path of the communication binary.

terminal = /path/to/terminal

Path to the x-windows terminal used for the client.

terminal_args = <blank>

Arguments to use when opening terminal windows. Otherwise takes defaults from $HOME/.Xdefaults or $<$HOME/.Xresources> file.

terminal_font = 6x13

Font to use in the terminal windows. Use standard X font notation.

terminal_reserve_top = 0

terminal_reserve_bottom = 0

terminal_reserve_left = 0

terminal_reserve_right = 0

Number of pixels from the terminal side to reserve when calculating screen geometry for tiling. Setting these will help keep cssh from positioning windows over your scroll and title bars title bars

terminal_size = 80x24

Initial size of terminals to use (note: the number of lines (24) will be decreased when resizing terminals for tiling, not the number of characters (80))

terminal_title_opt = -T

terminal_title_opt = -T

Option used with "terminal" to set the title of the window set the title of the window

terminal_allow_send_events = -xrm 'XTerm.VT100.allowSendEvents:true'

Option required by the terminal to allow XSendEvents to be received

title = cssh

title = cssh

Title of windows to use for both the console and terminals.

use_hotkeys = yes

Setting to anything other than "yes" will disable all hotkeys.

user = $LOGNAME

Sets the default user for running commands on clients.

window_tiling = yes

Perform window tiling (set to "no" to disable)

window_tiling_direction = right

Direction to tile windows, where ``right'' means starting top left and moving right and then down, and anything else means starting bottom right and moving left and then up

NOTE: The key shortcut modifiers must be in the form ``Control'', ``Alt'', or ``Shift'', i.e. with the first letter capitalised and the rest lower case. Keys may also be disabled individually by setting to the work ``null''.

A web site for comments, requests, bug reports and bug fixes/patches is available at <http://clusterssh.sourceforge.net/>

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If you have issues running cssh, first try:

"cssh -e [user@]<hostname>[:port]"

This performs two tests to confirm cssh is able to work properly with the settings provided within the .csshrc file (or internal defaults).

        1. test the terminal window works with the options provided

        2. test ssh works to a host with the configured arguments

Configuration options to watch for in ssh are

        - Doesnt understand "-o ConnectTimeout=10" - remove the option
          in the F<.csshrc> file

        - OpenSSH-3.8 using untrusted ssh tunnels - use "-Y" instead of "-X"
          or use "ForwardX11Trusted yes' in ssh_config (if you change the
          default ssh options from -x to -X)

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If you require support, please run the following commands and post it on the web site in the support/problems forum:

"perl -V"

"perl -MTk -e 'print $Tk::VERSION,$/'"

"perl -MX11::Protocol -e 'print $X11::Protocol::VERSION,$/'"

"cat /etc/csshrc $HOME/.csshrc"

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Use the debug switches (-d, -D, or -dD) will turn on debugging output. However, please only use this option with one host at a time, i.e. ``cssh -d <host>'' due to the amount of output produced (in both main and child windows).