
10
Advanced Topics
This chapter covers topics intended for the ad vanced user. The following topics are discussed:
• Enabling remote execution with OpenSSH (Section 1 0.1)
• Running an X terminal session from a remote node (Section 10.2)
10.1 Enabling Remote E xecution with OpenSSH
To reduce the risk of network attack s and increase the security of your HP XC system, the
traditional rsh, rlogin,andtelnet to ols are disabled by default, and OpenSSH is provided
instead. HP XC systems use the OpenSSH package to provide a more secure environmen t than
the traditional rsh, rlogin,andtelnet tools. OpenSSH provides a secure, encrypted
connection between your system and the HP XC system.
However, O penSSH requires, by default, that users enter their password every time that they
attempt to access a remote system . W hen first you use the ssh command to access the system,
or when attempting to use a tool such as TotalView to debug an ap plicatio n on the cluster, yo u
may be prom pted to e nter your password multiple times. To eliminate the multi ple requests,
use the procedure described below.
There are a number of ways in which to manage an OpenSSH environment. If you have not
already established your own procedures, the following procedure w ill help you to get started.
This procedure must be executed by each user, and assum es that your home directory is on a
file system that is shared across the cluster.
Log in to your account on the system and execute the following commands. Press the EN T ER
key in response to all questions.
$ ssh-keygen -t dsa
$ cd ~/.ssh
$ cat id_dsa.pub >>authorized_keys
$ chmod go-rwx authorized_keys
10.2 Running an X Terminal Session from a Remote Node
This section illustrates running an X
terminal session from a remo te node. A n X terminal
session can be invoked through SLURM o
r throug h LSF. Note that the procedure described
in this section creates an unencrypt
ed X terminal session, which is considered unsecure. The
information in this section assumes
the following:
• You are on a Linux, UNIX, or UNIX-like machine.
• You are on a non-XC machine, which is serving your local display.
• Your machine is on a trusted network.
Step 1. Determining IP Address of Your Local Machine
To begi
n, you need to determine the IP address of your monitor ’s display server (the m achine
servi
ng your monitor.), as shown in the following steps. You will use this IP address in later
comma
nds to run the X terminal session.
First, echo the display:
$ echo $DISPLAY
:0
Advanced To pics 10-1
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