• Create a JSON object using a cli tool: jq

  1 min read

  
  

  We can define jq tool as what's sed but for JSON data: We can use it for multiple purposes, for example to create a valid JSON object.

  Let's assume we want to create a JSON containing a multi-line string, we can simulate it like so or just using some file:

  $ echo -e "multi\nline"
  multi
  line
  

  07/12/2022

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• nmap: List only open ports while scanning

  2 min read

  
  

  While scanning using nmap a network for a specific port (using the -p option), it can be confusing toe get a list of hosts that are alive with either closed or filtered ports while we only care for open ports:

  $ sudo nmap -sS 10.12.16.0/24 -p 8123
  Starting Nmap 7.80 ( https://nmap.org ) at 2022-12-04 18:18 CET
  Nmap scan report for _gateway (10.12.16.1)
  Host is up (0.0010s latency).
  
  PORT     STATE  SERVICE
  8123/tcp filtered polipo
  MAC Address: CD:44:F0:F4:22:44 (Unknown)
  
  Nmap scan report for 10.12.16.10
  Host is up (0.00020s latency).
  
  PORT     STATE SERVICE
  8123/tcp open  polipo
  MAC Address: DC:A6:33:77:AA:BB (Raspberry Pi Trading)
  
  Nmap scan report for 10.12.16.33
  Host is up (0.00046s latency).
  
  PORT     STATE  SERVICE
  8123/tcp closed polipo
  MAC Address: B8:27:EB:8D:99:11 (Raspberry Pi Foundation)
  
  (...)
  
  Nmap done: 256 IP addresses (15 hosts up) scanned in 1.78 seconds
  

  05/12/2022

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• AWS CLI: Error parsing AWS config file

  1 min read

  
  

  One mistake on the .aws/config can lead to a very imprecise error message:

  $ aws sts get-caller-identity
  (...)
  botocore.exceptions.ConfigParseError: Unable to parse config file: /home/pet2cattle/.aws/config
  

  01/12/2022

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• Show current Kubernetes context in the menu bar

  2 min read

  
  

  Some commands might be safe to execute while connected to some environments, but can definitely break stuff is applied to the wrong Kubernetes cluster. However, having to execute kubectl config current-context too ofter to make sure we are connected to the right cluster is no fun either.

  With kubectx tray we can have a small icon on the tray bar to help us identify what's the current cluster.

  30/11/2022

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• Kubernetes - Check with RBAC: Can I...?

  2 min read

  
  

  When configuring RBAC permissions we might want to make sure we are configuring them correctly by checking what an user (or ServiceAccount) can do. We can use kubectl auth can-i for this.

  29/11/2022

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