Archive for Linux
Netdump, figuring out what caused that system crash
We have all been there before. Your server crashed, nothing indicates what happened. You check /var/log/messages and all you see is.. well.. nothing. With no sign of what happened, or indication of why it happened you are left to.. wait until it happens again. On Red Hat based systems, you have an answer. NetDump (diskdump [...]
Read moreDedicated Linux Server Checklist for the New Year.
If you have a dedicated Linux server, this list is for you. Below are a few items you need to do, to ensure your 2008 will be a bit brighter. This list is by no means comprehensive, but hopefully gets you started in the right direction this year. Check your backups and perform a full [...]
Read moreRestoring Plesk, new drive, old disk still available on same system.
Here was the scenario I faced. RHEL4 machine will not boot (according to data center), receives various library not found errors on bootup (Later, I found these errors were from an intruder who tried to install a rootkit, and it didn’t go so well. Most of /bin was corrupt). The data center recommends that the [...]
Read moreYUM issue: TypeError: Parsing primary.xml error
When running a ‘yum check-update’, I would receive an error. The error continued even after running ‘yum clean all’. The error is shown below: # yum check-update Setting up repositories core 100% |=========================| 1.1 kB 00:00 updates 100% |=========================| 1.2 kB 00:00 extras 100% |=========================| 1.1 kB 00:00 Reading repository metadata in from local files [...]
Read moreSecuring your Linux server
We deal with security related issues nearly every day. Many of these issues could be prevented with a few minor changes to php.ini along with the installation of mod_security. It is simply amazing how many machines are hacked, and then used for the sole purpose of sending spam, denial of service (DoS) attacks or Botnets.
Read moreRate limiting connections with iptables
You may find this iptables based method of limiting packets useful. For example, to drop connection from from someone who is trying to brute force your passwords via ssh. I have a particular case, where a customer wants to be notified if more than X number of SMTP connections are being generated from a particular [...]
Read moreRename a filesystem, or change a mount point
I was just asked today to provide a quick overview of the steps necessary to rename a filesystem. And here is what I came up with. Please use this information at your own risk, and always ensure you have a backup just in case something does not go well.
Read moreXEN Virtualization notes
I have recently been working on virtualizing Windows and Linux machines using Xen. A few things popped up along the way and a bit of research was done to make things work properly, these are some of the notes I took. Depending on the requirements, LVM may make sense for your implementation. One particular advantage [...]
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