Check TCP/443 reachability with netcat

Wed, 04 Nov 2026 15:00:00 +0100

When I troubleshoot routing or firewall access, I start with a quick TCP check from the Linux VM or Kubernetes pod that needs connectivity:

nc -zv ifconfig.io 443

In my example, netcat reported succeeded! for TCP/443. That confirms a TCP connection to the resolved address for ifconfig.io from the tested client at that moment. It does not prove which route was taken, which firewall or ZTNA rule matched, or whether HTTPS/TLS works.

Packet Capture on Ivan Versluis — Networknet

Check TCP/443 reachability with netcat