How can you ensure network access when using a firewall?

To ensure network access when using a firewall, you can perform the following actions:

• Check firewall rules: ensure that the necessary ports and protocols are allowed for the required IP addresses.
• Use connection testing utilities:
  • ping — check host availability.
  • telnet or nc (netcat) — check access to a specific port.
  • curl or wget — check access to a service via HTTP/HTTPS.
• Firewall logs: review logs to identify blocks.

Example of checking a port with netcat:

nc -zv example.com 80

If the connection is successful, network access is permitted.