Listen on TCP/443 with netcat

How I used a Linux netcat listener on TCP/443 to test remote connectivity and validate a ZTNA policy.

Networknet snippet showing nc -lvnp 443, the netcat flags, and a reminder to correlate listener connections with ZTNA policy logs.

Command and infographic terms

-l
Listen for incoming connections.
-v
Show connection details.
-n
Skip DNS lookups.
-p 443
Bind to local TCP port 443 on netcat versions that support this syntax.

During ZTNA testing, I used a temporary netcat listener on a Linux test host to check whether a remote connection could reach TCP/443.

nc -lvnp 443

When the connection appeared in the listener, I knew the TCP session had reached the test port. I then checked the ZTNA policy logs to confirm which access rule matched. Netcat alone cannot identify the policy that allowed the traffic.

This was a TCP connectivity check, not an HTTPS/TLS test. Binding to port 443 may require elevated permissions on Linux, and netcat syntax can vary by implementation.