Port 1723 — TCP
Legacy PPTP VPN control connections.
What is port 1723 used for?
PPTP control traffic; the VPN also depends on GRE, which is not a TCP or UDP port.
Transport protocol
TCP
Security precautions
PPTP is obsolete and insecure. Replace it with a supported secure VPN solution.
Should we open this port in the firewall?
Allow this port only when a required service uses it. Apply least privilege: restrict authorized sources, destinations and interfaces, and log connections where appropriate.
How do I check this port?
Test-NetConnection SERVER -Port 1723On Linux, nc -vz SERVER 1723 checks TCP connectivity only. A successful TCP connection does not validate the application, authentication or TLS configuration.
Port-to-service mappings are common conventions. Applications can use a different configured port; confirm the actual service and transport.