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1) Login security
HPCC periodically checks all passwords on our systems for
security using a dictionary-search algorithm. This form of
"cracking" is not feasible for general users because passwords
are "shadowed" on HPCC systems, but the check detects insecure
passwords which may be guessed. Insecure passwords are those
that contain, as substrings, dictionary words or names in any
language, forward or reversed. A better password contains a more
random collection of characters, but not so random that it must
be written on your monitor. A good method is to memorize a
sentence and use the first letter of each word, for this
sentence Agmitmas... It is also desirable to add numeric and
nonalphabetic characters to passwords.
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.
2) Cluster Internal Security
On first login to a cluster head node, SSH will 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, 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. Alternative MPI libraries are provided which use
ssh or rsh, and for each Fortran compiler, in /home/local.
Please include, link, and mpirun from the same library. The
Fortran version does not matter if you use only gcc/g++. On
Opteron compilers, there will be additional libraries for the
IA32 and AMD64 ABI's. There could be as many as 2 remote shells
x 3 Fortran versions x 2 ABI's or 12 MPI versions, but not all
the Fortran compilers will have AMD64 versions.
3) Data Security
We
currently store data on a resilient system and back up a limited
amount of user data, however we strongly
encourage users to maintain a copy of all the data which is
absolutely critical for their research. Ultimately, we
do not have the budget to guarantee that data will not be lost.
As a result, it is the researcher’s responsibility to back up
their own important data on their own systems.
In HPCC systems, the conflict
between performance, size, cost, and reliability is generally
resolved in favor of large size at medium performance at low
cost. Reliability necessarily suffers. Most of the cluster disk
storage is composed of arrays of consumer-grade disks. Disk
failures are relatively common, but single-disk failures are
usually automatically handled by RAID software.
Critical files, such as source code and output required for a
paper or dissertation, should be periodically copied to each
user's personal machine and further backed up to removable media
and stored offsite.
Regardless of the directory permissions, root users (HPCC staff
and anyone who might completely crack the system) can read your
files. If you want to make extremely sure that no-one reads your
files, install the PGP package and encrypt your critical files.
You would also need to eliminate backup copies from the Tivoli
system. However, if you encrypt and then forget your pass
phrase, the files can be extremely difficult to decrypt
depending on the size of your encryption key.
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