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🛡️ Research ports and firewall rules

TCP/UDP Port Lookup & Windows Firewall Helper

Search common TCP and UDP ports, understand their typical services and build a reviewable Windows Firewall command without running anything automatically.

Updated July 23, 2026✓ Free to use🔒 Local browser processing
🔒 No account or data upload required

Look up a port

Search by port number, protocol, service or purpose.

Windows Firewall command helper

About this utility

What does a TCP and UDP port lookup show?

Network ports are numbered communication endpoints used by applications and services. A port number can suggest the expected protocol, but it does not prove which program is listening or whether the traffic is safe. You should combine a lookup with local process information and network context.

This utility explains common ports and generates Windows Firewall commands based on the direction, protocol and action you choose. It does not test the port, scan a remote host or make firewall changes automatically.

Identify common services

Review typical uses for frequently encountered TCP and UDP port numbers.

Understand exposure

See why some services should not be exposed directly to untrusted networks.

Generate transparent rules

Create a command you can review before applying an allow or block rule.

Best practices

How to review a Windows Firewall rule safely

  1. Confirm the application, service, protocol and direction that actually require the port.
  2. Prefer an application-specific or narrowly scoped rule over broad exposure.
  3. Do not expose remote administration, database or file-sharing ports directly to the public internet.
  4. Document the rule name and remove temporary rules when they are no longer needed.

Safety note: This utility provides educational troubleshooting guidance. Back up important data before system changes and use qualified support when hardware damage, data loss or electrical risk is possible.

Common use cases

Common port lookup examples

Web trafficPorts 80 and 443 are commonly associated with HTTP and HTTPS.
Name and address servicesDNS and DHCP use well-known TCP or UDP ports depending on the task.
Remote administrationRDP and SSH ports require strong authentication and careful network exposure.
File and database servicesSMB and database ports should normally be limited to trusted systems and networks.
Continue troubleshooting
📶 Related utilityWi-Fi Troubleshooting AssistantDescribe which devices are affected and what the connection is doing to generate a focused Wi-Fi troubleshooting checklist and Windows network commands.⌨️ Related utilityWindows Repair Command GeneratorChoose a Windows problem and generate an ordered CMD or PowerShell command set for diagnostics, system-file repair, networking, disks and reports.Related utilityPC Troubleshooting Checklist →Record symptoms, completed checks and support notes.

Frequently Asked Questions

Does opening a port make an application work automatically?

No. The application must be listening on that port, and routers or upstream firewalls may also need configuration.

Is it safe to expose Remote Desktop on port 3389?

Direct public exposure is high risk. Prefer a VPN or Remote Desktop Gateway, MFA, Network Level Authentication and strict source restrictions.

How can I see which process owns a port?

Use Resource Monitor, netstat with process IDs, or PowerShell Get-NetTCPConnection and then map the PID to a process.