• 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 follows or just use some file with cat:

  $ 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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• Troubleshooting Spinnaker: Rosco Bakes

  2 min read

  
  

  If we have a baking stage failing that we cannot get our heads around, it might help to be able to retieve some extra information about it. We can get more details about connecting to the redis instance that rosco uses.

  01/06/2022

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• Generate public SSH key from existing private SSH key

  1 min read

  To be able to successfully connect using SSH keys we need to have the private key on the client side and the public key set on the server side (where we want to connect). If we only have the private key, we can generate a public SSH key from it

  24/12/2021

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• Monitoring the progress of dd

  2 min read

  For a long time we were not able to properly monitor the progress of a dd command unless we were using pv of having another process to periodically send a SIGUSR1 to the dd process

  17/09/2021

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