Category: Network
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F5 – RST or ICMP Packet Rate
You can follow SOL13151 in order to increase the packets/sec value. However, I would caution against doing it or at least recommend keeping the value smaller. The default setting is in place to prevent the F5 from overwhelming its resources by sending out RST. This could potentially end up being a self-inflicted DoS. So, either don’t change […]
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GTM Code Upgrade
These are a few quick checks as part of the GTM code upgrade maintenance that will be useful. As part of the maintenance preparatory work, check the license “service check date” as per K7727 Before starting the code upgrade and after the code upgrade, the following can be utilized to check the status of the […]
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Network Troubleshooting Tools
This is a short list of commonly available network troubleshooting tools that has been of use to me: Ping. traceroute. nslookup/dig curl. Error logs on the device. tcpdump. Developer tools within a browser like Chrome/FF. Wireshark.
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Clear SSH Key File
A simple way to clear the contents of ssh key file without deleting the file: echo -n > /home/user/.ssh/known_hosts
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F5 GTM – DNS Query Processing Order
When a DNS query arrives at a F5 GTM/DNS, this is the processing order for the DNS query. 1 – DNS Query is processed by the Listener. 2- If Recursion Desired (RD) flag is set in the incoming query and if the DNS Profile associated with the Listener has “Process Recursion Desired” enabled, the following […]
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Ansible Playbook Optimizing
$ cat ansible.cfg [defaults] hostfile = ./hosts host_key_checking = False timeout = 5 log_path = ./logfile.txt forks = 50 gathering = smart [ssh_connection] pipelining = True The above file shows the content of ansible.cfg file. I have added the following to make my playbook run faster: forks gathering pipelining Forks indicate the number of parallel […]
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Ansible & Python 3
While using Ansible 2.2 and Python 3.x, I ran into the following error: ERROR! Unexpected Exception: No module named ‘urlparse’ Workaround: 1. Downgrade Python to 2.x 2. If there is no root level permission, use virtual env: virtualenv –python=python2.7
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iRule HTTP Referer
This is a simple iRule that performs redirects based on HTTP Referer: when HTTP_REQUEST { if { ([HTTP::header exists “Referer”]) and ([URI::host [HTTP::header value Referer]] eq”special.com”) } { HTTP::redirect https://www.site.com/special-client/ } else { HTTP::redirect https://www.site.com/generic-client } }
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Ansible Components
What? Ansible is a simple IT automation tool. Ansible exists as CLI & GUI. GUI is called the Ansible Tower and Ansible, Inc., which is owned by RedHat, officially supports this. Controlling Nodes: The Network infrastructure is managed from these Controlling Nodes. In an Enterprise environment, Controlling Nodes are typically Linux bastion servers. Managed Nodes: Managed Nodes […]