Bhushan,

SQLNET.CRYPTO_SEED
Specifies the characters used when generating cryptographic keys. The more random the characters are, the stronger the keys are. This is required whenever encryption or checksumming is turned on
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Check the listener process
ps -ef|grep tns
This will give the list if the listener is running.

If it is running ,shut it down and restart.
Sometimes it happens even lsnrctl status command will hang.
You have to check the CPU consumption.

If it is too much sometimes listener hangs .
During that situation ,lsnrctl stop also willnot help.

So give : kill - 9 listenerprocessid

Then restart the listener.

If that is not the situation,Check with the sysadmin for the portno . Jus' try to get a different portno which is not conflicting.

Edit listener.ora accordingly and restart ..

Hope this helps