The
Generation of Random Number are done by using Math.random() or SecureRandom. The
Source for generating the random numbers can be configured in such a way that
they can depend on the Operating System. Java uses its own source for
generating the Random numbers but for better random numbers, the source for generating
the random numbers can assigned to the underlying operating System hardware
Signals which are generated from the interactions from the network ,keyboard
and other devices.
In
RHEL, there are 2 files available that help in generating the Random numbers
/dev/random
&
/dev/urandom
The
Random number generator uses hardware noises for generating the random numbers.
The noise generated by the hardware is thus stored inside the entropy pool. The
generator also has the information on how much bits of information is available
in the entropy pool.
From
using this entropy pool, the random numbers are generated.
The /dev/random
will only return random date within the estimated number of bits of noise in
the
entropy
pool but one issue with this is the /dev/random will be blocked until
additional noise is generated or bits available in the entropy pool. If no bits
are available in the entropy pool, the /dev/random will be blocked.
The
/dev/urandom will return as much data requested.
If
your system does not have /dev/random and /dev/urandom created already,
they can be created with the
following commands:
mknod -m 644 /dev/random c 1 8
mknod -m 644 /dev/urandom c 1 9
chown root:root /dev/random
/dev/urandom
The
library used for random number generation in Sun's JVM relies on /dev/random by
default for Linux platforms. For configuring the random number generation with
Weblogic,
Check
if /dev/random works fine
head
-n 1 /dev/random
If
the command returns immediately, you can use /dev/random as the
default generator for SUN's JVM. If the command does not return immediately,
use these steps to configure the JVM to use/dev/urandom .This can be configured
as
-Djava.security.egd=file:/dev/./urandom
and added to the Weblogic startup script
Happy learning
