For medium to large size projects the network setup can be quite complex, especially if it involves several external partners or third-party networks (VPN, MPLS etc).
Normally network changes are done by network engineers that do not have access to the servers and therefore cannot verify the changes they make.
When I have to verify a network change, firewall opening, NATing etc, I have in the past often used telnet.
This is very simple and (more...)
- Entropy pool
- Monitoring entropy
- Using /dev/urandom
- JRE – java.security
- rngd daemon
- Additional information
In computing you often need random numbers. They are used for encrypting stuff but also for lots of other things.
Patching WebLogic is necessary but not fun. To help out I have created a simple Bash script for installing CPU/PSU patches.
For information about CPU, PSU and SPU patches check this post.
The script is using BEA Smart Update so it is for WebLogic Server 12.1.1 and older. WebLogic Server 12.1.2 has switched from BSU to OPatch.
#!/bin/bash # --------------------------------------------------------------------------- # cpuPatch.sh # Peter Lorenzen # Version 0.9 (more...)
Are you signed up yet for Ohio LinuxFest on Sep. 13-15? I'll be there to present
IPython for non-Pythonistas
Break out of your (bash) shell! IPython and the IPython Notebook have swept over the Python programming community, but they're not just for Python programmers - they make for high-powered shell (more...)
For my example, (more...)
I have seen several clients who are struggling to decode page allocation failures on Exadata, in this post i will try to explain how to read the backtrace. The following is an anonymized client case where page allocation failures are leading up to a node reboot.
Jan 1 11:58:02 dm01db01 (more...)
We will complete our lab by installing the Oracle Database software, create a Pluggable database and take a look in the Oracle Enterprise Manager Database Express.
The steps to install and create an Oracle Database 12c are:
1 – Go to the database directory created when unzipped the 2 Oracle (more...)
But now rebooting works like expected (with Ubuntu and Windows 8).After some more reboots and trying to start ubuntu, booting ubuntu only works randomly. Sometimes it worked after walking through BIOS/UEFI. Sometime it did (more...)
Dayton folks - are you coming to the Dayton Linux User Group's Installfest tomorrow?
The main point of our Installfests is to get everyone together for mutual help setting up and configuring computers and programs. But we like to throw in some educational talks, too, and I volunteered to give (more...)
Today I installed the accompanying JDeveloper 188.8.131.52 on the same machine. Everything went fine, except that apparently the installer failed to (more...)
Recently, I’ve been faced with a strange problem: around 10AM every morning, my database was showing signs of IO contention. Wait times for db file sequential and multipblock reads were increasing for no apparent reason and there were no signs of increased activity reported by the users. Fortunately, my system (more...)
As you all may know, ASMLib is a recommended module for Oracle databases running on Linux platforms and it is an embedded module for UEK (Oracle Unbreakable Kernel) users. Oracle announced that (two years ago or so) they will no longer maintain ASMLib for Red Hat compatible kernel but this does not mean that they abandon the project, rather it is mainly related to the effort they need to put in maintaining the module for multiple kernel versions.
A while ago, Oracle added a new feature to ASMLib allowing ASM devices to choose between physical or logical block sizes in (more...)
I have upgraded one of my Oracle Linux boxes to Oracle Linux Release 5.9 which introduces several new things (Release Notes). Just to mention three of them
- firefox 10 (Although we have discuss to install latest version of it in Oracle Enterprise Linux for Home User: Install Latest Firefox Version )
- uek2 vanilla kernel branched from Linux Kernel Release 3.0.36
- Transparent Huge Pages
Download and update yum repository file
[root@localhost yum.repos.d]$ cd /etc/yum.repos.d [root@localhost yum.repos.d]$ wget http://public-yum.oracle.com/public-yum-el5.repo [root@localhost yum.repos.d]$ mv (more...)
I bet if any of you have an exposed server to an internet connection, without properly firewall protection, that your server is under heavy fire from hackers around the “world”… By the world I mean mostly China and Russia ssh attacks. If you’re curious, on Linux you can check the (more...)
On Linux low entropy can cause certain operations to be very slow.
SSL operations need entropy to ensure randomness. Entropy is generated by the OS when you use the keyboard, the mouse or the disk.
If an SSL operation is missing entropy it will wait until enough is generated.