AIX 6.1 OS Patches the Easy Way

Summary

Patching AIX can be intimidating at first for someone coming from the Windows / Linux world. AIX has capabilities that natively support production quality operations. One of these qualities is that one can install patches on an alternative volume, make that volume bootable for testing and allowing an easy way out if something doesn’t work right. Since AIX 5.3, it is also possible to install patches on the same volume as the boot volume and define boot profiles to boot at a certain patch level. In this post we will just look at the basics of patching, emulating the equivalent of “yum update” or the “windows express update” (taking Linux / Windows as analogy).

Steps

  • Download available patches for current technology level:
    smitty suma <Enter>
    Download Updates Now (Easy) <Enter>
    Download All Latest Fixes <Enter> <Enter>
  • Install patches:
    smitty update_all
    specify INPUT device: /usr/sys/inst.images/installp/ppc <Enter>
    go down to "ACCEPT new license agreements?" <Tab> (to switch to "yes") <Enter> <Enter>

That’s it. You can reboot in case there were kernel updates or APARs that recommend a reboot. To check the current patch level, you can run oslevel -s.


Cacti Install on RHEL 5 or CentOS 5

Introduction

Cacti is a great tool to graph performance of the various hardware components of a network. With the use of the yum repository manager, it is very simple to install on Red Hat Enterprise Linux 5 or CentOS 5.

Install steps

  • First make sure that you have the dag repository configured in yum. Edit or create the file /etc/yum.repos.d/dag.repo:
    [dag]
    name=Dag RPM Repository for Red Hat Enterprise Linux
    baseurl=http://apt.sw.be/redhat/el$releasever/en/$basearch/dag
    gpgcheck=0
    enabled=1
    protect=0
  • Now install the required packages:
    sudo yum install net-snmp mysql mysql-server cacti
  • Edit the /etc/httpd/conf.d/cacti.conf file to allow access to cacti as needed.
  • Make sure Apache and MySQL are started and set to start automatically:
    sudo service mysqld start
    sudo service httpd start
    sudo chkconfig –level 345 mysqld on
    sudo chkconfig –level 345 httpd on
  • Set up the cacti database in MySQL:
    sudo mysqladmin –user=root create cacti
    cd /var/www/cacti
    sudo mysql cacti < cacti.sql sudo mysql --user=root mysql mysql> GRANT ALL ON cacti.* TO cactiuser@localhost IDENTIFIED BY ‘cactiuser’;
    mysql> SET PASSWORD FOR cactiuser = PASSWORD('my_super_secret_cacti_password');
    mysql> flush privileges;
    mysql> exit
    sudo mysqladmin –user=root password "my_super_secret_root_password"
  • Setup the cacti poll schedule in /etc/crontab:
    */5 * * * * cacti php /var/www/cacti/poller.php > /dev/null 2>&1
  • Run the cacti installer in the browser:
    http://your.server.com/cacti/index.php
    provide the user and password for the database, you can accept all defaults and just click next
  • That is it, you are good to go.

References

Installing Cacti on CentOS with yum


Setting up shared VMWare Fusion host folders on CentOS and RHEL guest

Problem

How to view folders from the Mac that hosts the VMWare Fusion guest operating system CentOS or Red Hat Linux?

Solution

  • First, make sure that the VMWare Tools are installed. That always helps.
  • Next, in the WMWare configuration menu of the guest, set up the desired shared folders. There might be already a default shared folder pointing to the user’s home directory.
  • Next, in the guest OS, ls -ld /mnt/hgfs will display the available shared folders.

References

[CentOS-virt] CentOS 5.1 guide for VMware Fusion


OpenVPN write UDPv4: Can't assign requested address (code=49)

Problem

On Max OS X, when trying to connect to an OpenVPN gateway, you may encounter the following error:
2010-01-21 05:14:59 write UDPv4: Can't assign requested address (code=49)
2010-01-21 05:15:01 write UDPv4: Can't assign requested address (code=49)
...

The error would repeat itself indefinitely.

Root Cause

The TCP stack of the Mac has a bug that can cause the routing table to get corrupted.

Solution

The routing table needs to be flushed on the interface used to connect to the Internet. Typically,

  • en0: ethernet (wired) interface
  • en1: wlan (wireless) interface

The easiest way is to flush the routes is to reboot. The elegant way however is to shut down the interface connecting the Mac to the Internet, flush the routing table, and bring the interface back up. For example, assuming a wired connection, open a terminal or an X11 xterm window and issue the following commands:
sudo ifconfig en0 down
sudo route flush
sudo ifconfig en0 up

In case the command line hangs after the flush command, just open a new terminal and run the last command from there. When you are done, you can close all terminals. If you are connecting with wireless, replace en0 with en1.

References

OpenVPN error: write UDPv4: Can’t assign requested address (code=49)


Qpid, an AMQP implementation

Joshua Kramer has an article in LJ about Qpid and AMQP. One of the most compelling aspects of Qpid is its cross plaform and cross language capability. Finally there is a message broker that is easy to use and has ready to go clients for C++, Java, Python, Ruby and .Net. Take a look and let me know what you think.