Metric Extension : HugePages & capacity planning

For big database servers (used for consolidating multiple databases) with a lot of memory and a lot of preallocated free HugePages it’s important to take into consideration the number of free HugePage for capacity planning .

The default “memory used” metric calculated as (MemTotal – (MemFree + Buffers + Cached)) and as (MemTotal – (MemFree – Buffers – Cached – Slab)) in recent version as shown by the free command  (Ref: https://access.redhat.com/solutions/406773) don’t take into consideration the amount of Free HugePages. Using the metric extension feature of cloud control we can easily alleviate that.

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Tracking Oracle Database Binaries files changes

The Linux Audit system provides a way to determine the violator of the security policy and the actions they performed such as tracking malicious changes on the oracle executable.

Using Linux Audit system we can basically do the following activities :

  • Watching file access
  • Monitoring system calls
  • Recording commands run by a user
  • Recording security events

In this short blog post i will show how we can easily use it to catch changes in “./bin” directory.

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Using LD_PRELOAD to implement a hidden trojan in an oracle database

In one of my previous post  i showed how we can inject a backdoor in an ORACLE database based on Dennis Yurichev findings.The described method required the modification of the oracle executable files.  Few days ago Rodrigo Jorge shared a blog post explaining how we can add another layer of security to the oracle binaries files to protect them against improper changes. That motivated me to check if i still can implement the hidden Trojan without modifying the oracle executable files ?

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Playing with oracle DB 18c on-premises before official release

Rodrigo Jorge has already explained a great way to install and play with Oracle 18c DB instance on-premises using Exadata binaries downloaded from edelivery. The basic idea is to install the oracle exadata binaries and before creating the database replace the library “libserver18.a” with the  version gotten from an oracle cloud instance  (Using Oracle Cloud trial account). And that’s it !

But for those like me that don’t have an international credit card required to create an Oracle Cloud trial account  (Yes i don’t have one 😦 ) or don’t want to create one  ! How to proceed to get a copy of this working libserver18.a library ? May be ask one of the oracle folks to upload it to somewhere and hope that there is no backdoor on it :p  or just try to hack it your self 😀

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Tracing PL/SQL subprogram calls with parameters values [Dynamic tracing]

The purpose of this blog post is demonstrate again the power of Linux dynamic tracing/instrumentation tools.

In my last blog post Enhancing DBMS_OUTPUT using systemtap i showed how we can track  the parameter values passed to “dbms_output.put_line” routine using systemtap.That was a very simple example because we already know the type of the arguments passed (a simple VARCHAR2) and also because there is only ONE parameter.

Tracking PL/SQL routine calls arguments using dynamic tracing utility like perf or systemtap can become quite complex depending on many things like :

  • Argument types
  • Argument number
  • Argument passed  By Value/By reference
  • Subprograms type (nested/package/standalone subprogram)
  • Optimization level (ex: inlining of call of procedure)

Time for the serious stuff  with dynamic tracing tool PERF ! 

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