From thehackernews, it was said when the UID is larger than INT_MAX, which is 2147483647, privilege validation is improperly handled and that gives the user right to run systemctl commands as if he/she is a privileged user. What is my INT_MAX? Though it’s hard to imagine who would use such an UID when they usually starts with 1000. However, if Linux is integrated with AD, the AD users ID are mapped…

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Cool feature on Azure – Run Command Script

I don’t think I’ve ever said anything good about Azure, but I’ve finally ran into one today. Someone screwed up sshd_config and the service would not start anymore. With the run script tool, I was able to revert the config to the original version and restart the service. Fortunately, the changes were checked into RCS, which made recovery relatively easy. Here, I checked out the original version of the config…

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tmux send input to all panes

Run tmux and have it split into 2 panes, each running a separate process, and send input to all panes. Here I start up one container in each pane, then turn on input broadcast. One can easily modify the commands and have tmux gives control over a cluster of servers. Or ssh to different servers and manage them all at once.

This is trememdously useful for myself. To turn…

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Add security group to all ec2 instances

If you ever need to take over management of an AWS farm, it’s very likely you will need to attach SG to all instances. Be that for monitoring or access. Here is a bash script to add 1 SG to all instances. You will need to first setup a profile on awscli. Then run the script with the profile name as first argument, and the SG id as the second.…

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Building my first Linux package

Let’s take a look at how to build a really simple Linux package. The most common package formats are definitely .deb and .rpm. One will find them on Debian-variants and Redhat-variants respectively. In the following examples, a package will be created and it will contain 1 script.The script depends on Python so I want the package management tool to handle that for me too. The script’s name is goldenRatio.sh and…

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php debugging

There are a couple ways to debug php applications. We can enable core dump and/or install Xdebug. Enable php core dump on php-fpm First instruct the kernel to write core dumps to /tmp. On some system, dumps are fed to abrtd.

In php-fpm.conf, add the following

Restart php-fpm and use gdb to debug the dump files. To get the most out of the dump files, install the debuginfo…

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kubernetes quickstart

kubernetes and docker In this post, I’ll be deploying a docker cluster running a number of nginx containers. Bare with me though as I am still learning about kubernetes and docker. Machines The master node will be controlling the worker nodes. Deployments will not run on the master node itself. From my experience, at least 1.5Gi of memory is needed for these machines. k8s-ms | k8s-wk1 | k8s-wk2…

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Brought to my attention by a friend, I gave ipfs a try and here is what I did to get started:

The file is stored locally under the blocks directory:

Once a file is added to ipfs, it cannot be deleted. References: https://ipfs.io/docs/commands/

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Take LVM snapshot before ubuntu upgrade

Ubuntu upgrade can be a challenge Ubuntu 18 is coming up in a few months. I started using Ubuntu on my machine since version 9.10 and it has gone through 8 upgrades. I’m running 17.10 now. If memory serves me right, my system crashed 2-3 times during these upgrades. In fact, those were the only downtime I have on this machine. In the early days, upgrade isn’t very mature IMO.…

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