RE: DoS attack from java connections - how to avoid

From: D'Hooge Freek <>
Date: Tue, 31 Aug 2010 17:58:41 +0200
Message-ID: <>


These "dead" processes, are they processes on the db server or on the application server? In neither case it seems normal to me that a process keeps existing after a failed connection attempt, but if this is on the db server you can try if enabling dead client detection (sqlnet.expire_time) would help in cleaning up those processes.


Freek D'Hooge
Oracle Database Administrator
tel +32(0)3 451 23 82

From: [] On Behalf Of John Hallas Sent: dinsdag 31 augustus 2010 11:07
To: oracle_l
Subject: DoS attack from java connections - how to avoid

We had an application that repeatedly connects to the database via java connection pool fail because the account had become locked. The application kept on trying, the database did not allow the connection and we ended up with thousands of 'dead' processes causing the unix server to hang as all memory was used up.

The obvious thing to fix in our case was some form of application logic to recognise that failed connections had been made and stop the repeated connection attempts.

However this could also be used in a denial of service attack. What steps could we take to reduce that risk. The problem as I see it is that the database has reacted correctly and there is not much more we could do at the database level. However I am always open to suggestions


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-- Received on Tue Aug 31 2010 - 10:58:41 CDT

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