Restore a service from client to answer

Articles

• Network diagnostics — A ladder of connectivity checks — from the gateway to DNS and the destination port.
• ss — sockets and ports — Shows who is listening on ports and which connections are open; a netstat replacement, faster with many connections.
• curl — HTTP requests from the console — curl sends HTTP and HTTPS requests from the console: status code, headers, the whole exchange, certificate checks.
• nc — checking ports and transferring data — Checking whether ports are reachable, simple data transfer over TCP/UDP.
• Firewall — nftables / ufw — A mechanism filtering network traffic according to specified conditions and actions.
• nginx — web server and reverse proxy — A web server and reverse proxy whose configuration should be checked before applying changes.