General conditions for access
Per Texas statutes, TTU information resources are strategic assets of the state of
Texas that must be managed as valuable state resources. As such, use of TTU information
resources is subject to university OPs and other applicable laws. Unauthorized use
is prohibited, usage may be subject to security testing and monitoring, misuse is
subject to criminal prosecution, and users have no expectation of privacy except as
otherwise provided by applicable privacy laws.
Login security
HPCC rely on TTU e-raider authentication system to check user credentials on our
systems. All users use their e-raider id and password to log in HPCC clusters.
HPCC systems have RSA authentication enabled for passwordless login. You may choose
whether to enable this on each system by adding RSA keys from remote systems to ~/.ssh/authorized_keys.
Please be careful. If enabled, this allows an intruder to enter all of your accounts
if one is cracked. We strongly suggest that you do not add a key for a system that
is itself insecure (MS Windows, security not up to date, telnet enabled, etc.) as
this allows intruders user access to HPCC systems which can then be escalated to root
access and total control.
Cluster Internal Security
On first login to a cluster head node, SSH may ask you for a key phrase. This is not
generally needed. It is reasonably secure, and makes login to the compute nodes simpler,
if you leave this key blank (hit the enter key at this prompt). From the head node,
you should be able to either ssh or rsh to all of the compute nodes in that cluster
without a password. If either ssh or rsh prompts for a password on cluster head to
compute login, please contact HPCC staff at hpccsupport@ttu.edu, as parallel software generally depends on passwordless login. More complex methods
will be required if you have a non-blank SSH key phrase on the cluster head nodes.
Remote shell or rsh only works within each cluster. If you are extremely concerned
about security, you may wish to use only ssh within clusters. rsh is faster as it
does not encrypt each transmission, but the transmissions can be intercepted and decoded.
This is generally not an issue, since root access to the cluster is required to intercept
the messages, and this interception procedure would not be necessary for a cracker
who already had root access.
MPI on clusters also uses either ssh or rsh for data transmission.
Please also read and observe the data access, permissions, and security policies on
the TTU HPCC Data Policies page.
Access Permissions
By default in Linux systems, users have read, write and execute permissions to the
directories and files that they own. Meanwhile the directories and files are readable and executable to other users, including the
users in the same group of the owner. Basically a user is the owner of the directories /home/user-id, /lustre/work/user-id,
and /lustre/scratch/user-id, as well as all files and directories under them. A user
also owns the temporary files or directories in /state/partition1 on compute nodes,
if their jobs create temporary output there. If you are concerned about the permission
settings, for example, you do not want others to read your files, you can change the
permission by command "chmod" with appropriate options. For the details, please run
"man chmod" to get the manual of chmod command, or contact hpccsupport@ttu.edu.
Examples of reasons to set stricter than normal permissions would be to protect files
from inadvertent sharing, such as homework or class personal activities, or protection
of proivate keys such as those in your .ssh folder. In general, you should not assume
that files on a shared cluster file system are private and should take steps such
as keeping any sensitive data off of the cluster file systems and instead moving them
to external storage under your direct control. You may also need to request to delete
any backup copies from the HPCC backup system, if applicable.
Regardless of the directory permissions, root users (HPCC staff and TTU security personnel)
are permitted to access user files as needed for management of storage systems or
for security-related investigations. Sponsoring faculty/staff can also request to
access your files for purposes of continuity of research.
