Setting Up Ansible for AWS with Dynamic Inventory (EC2)

If your Ansible inventory fluctuates over time, with hosts spinning up and shutting down in response to business demands, the static inventory solutions described in Working with Inventory will not serve your needs. You may need to track hosts from multiple sources

Ansible integrates all of these options via a dynamic external inventory system. Ansible supports two ways to connect with external inventory: Inventory Plugins and inventory scripts.

If you use Amazon Web Services EC2, maintaining an inventory file might not be the best approach, because hosts may come and go over time, be managed by external applications, or you might even be using AWS autoscaling. For this reason, you can use the EC2 external inventory script.

You can use this script in one of two ways.

  1. The easiest is to use Ansible’s -i command-line option and specify the path to the script after marking it executable:
  2. The second option is to copy the script to /etc/ansible/hosts and chmod +x it. You will also need to copy the ec2.ini file to /etc/ansible/ec2.ini. Then you can run ansible as you would normally.

You can test the script by itself to make sure your config is correct:

After a few moments, you should see your entire EC2 inventory across all regions in JSON.

If you use Boto profiles to manage multiple AWS accounts, you can pass --profile PROFILE name to the script.

You can then run --profile prod to get the inventory for the prod account, although this option is not supported by ansible-playbook. You can also use the AWS_PROFILE variable – for example:


How to fix different times in Dual boot mode ( Windows and Linux)

Your PC stores the time in a hardware clock on its motherboard. The clock keeps track of time, even when the computer is off. By default, Windows assumes the time is stored in local time, while Linux assumes the time is stored in UTC time and applies an offset. This leads to one of your operating systems showing the wrong time in a dual boot situation.

To fix this, you have two options: Disable RTC in Linux, or make Windows use UTC time. Don’t follow both steps of instructions or they still won’t be speaking the same language! We recommend you make Linux use local time, if possible.

1. Disable RTC on Linux

timedatectl set-local-rtc 1 --adjust-system-clock


2. Use UTC in windows

How to use ipset command on linux to block bulk IPs

ipset is a companion application for the iptables Linux firewall. It allows you to setup rules to quickly and easily block a set of IP addresses, among other things.


Debian based system

# apt install ipset

Redhat based system

# yum install ipset

Blocking a list of network

Start by creating a new “set” of network addresses. This creates a new “hash” set of “net” network addresses named “myset”.


Add any IP address that you’d like to block to the set.

Finally, configure iptables to block any address in that set. This command will add a rule to the top of the “INPUT” chain to “-m” match the set named “myset” from ipset (–match-set) when it’s a “src” packet and “DROP”, or block, it.

Blocking a list of IP addresses

Start by creating a new “set” of ip addresses. This creates a new “hash” set of “ip” addresses named “myset-ip”.


Add any IP address that you’d like to block to the set.

Finally, configure iptables to block any address in that set.

Making ipset persistent

The ipset you have created is stored in memory and will be gone after reboot. To make the ipset persistent you have to do the followings:

First save the ipset to /etc/ipset.conf:

Then enable ipset.service, which works similarly to iptables.service for restoring iptables rules.

Other Commands

To view the sets:


To delete a set named “myset”:


To delete all sets:

How to configure IPsec/L2TP VPN Clients on Linux

After setting up your own VPN server, follow these steps to configure your devices. In case you are unable to connect, first, check to make sure the VPN credentials were entered correctly.

Commands must be run as root on your VPN client.

To set up the VPN client, first install the following packages:

Create VPN variables (replace with actual values):

Configure strongSwan:

Configure xl2tpd:

The VPN client setup is now complete. Follow the steps below to connect.

Note: You must repeat all steps below every time you try to connect to the VPN.

Create xl2tpd control file:

Restart services:

Start the IPsec connection:

Start the L2TP connection:

Run ifconfig and check the output. You should now see a new interface ppp0.

Check your existing default route:

Find this line in the output: default via X.X.X.X .... Write down this gateway IP for use in the two commands below.

Exclude your VPN server’s IP from the new default route (replace with actual value):

If your VPN client is a remote server, you must also exclude your Local PC’s public IP from the new default route, to prevent your SSH session from being disconnected (replace with actual value):

Add a new default route to start routing traffic via the VPN server:

The VPN connection is now complete. Verify that your traffic is being routed properly:

The above command should return Your VPN Server IP.

To stop routing traffic via the VPN server:

To disconnect: