Answer took from oracle forum, here:
java.security.SecureRandom is a standard API provided by sun. Among various methods offered by this class void nextBytes(byte[]).
This method is used for generating random bytes. Oracle 11g JDBC drivers use this API to generate random number during
login. Users using Linux have been encountering SQLException("Io exception: Connection reset").
The problem is two fold:
The JVM tries to list all the files in the /tmp (or alternate tmp directory set by -Djava.io.tmpdir) when
SecureRandom.nextBytes(byte[]) is invoked. If the number of files is large the
method takes a long time
to respond and hence cause the server to timeout
The method void nextBytes(byte[]) uses /dev/random on Linux and on some machines which lack the random
number generating hardware the operation slows down to the extent of bringing the whole login process to
a halt. Ultimately the the user encounters SQLException("Io exception:
Connection reset")
Users upgrading to 11g can encounter this issue if the underlying OS is Linux which is running on a faulty hardware.
The cause of this has not yet been determined exactly. It could either be a problem in the hardware or the fact
that for some reason the software cannot read from dev/random
a solution seems to add this setting to the jvm
-Djava.security.egd=file:/dev/./urandom
