Firewall

• Which layer does Windows firewall works??
• Types
  • Layer-3
  • Layer-4
  • Layer-7
• Do all the ports always open on any computer/VM unless firewall explicitly blocks?
  • states of ports - open, closed
  • port scanning
• commands
  • nmap
  • ufw
• Reference
  • https://en.wikipedia.org/wiki/Open_port
  • https://serverfault.com/questions/792572/what-does-a-layer-3-4-firewall-do-that-a-layer-7-does-not
  • https://www.reddit.com/r/netsecstudents/comments/m77s76/at_what_network_layers_are_the_ips_blocked_and/

Port scanning

• What is it?
• nmap (Network Mapper) can be used
  • https://lf-onap.atlassian.net/wiki/spaces/DW/pages/16294589/Nmap

nmap <host-name>