Port Checker – UDP & TCP Port Lookup
Identify the conventional service for a TCP or UDP port, validate a port number, and learn how to investigate connectivity. This is an offline port-reference lookup—not a live open/closed scanner.
Look Up Port
Lookup Result
Known portPort Range Overview
Common Ports Reference
| Port | Protocol | Service | Description |
|---|
Browser-based lookup: port-number validation, service-name matching, protocol filtering, range classification, table filtering, and result rendering are handled locally from this page's bundled common-port list. No hostname or remote endpoint is contacted by the lookup itself. The page still loads interface and advertising resources from external providers.
Free TCP and UDP Port Lookup
The Utiliverse Port Checker helps identify what a network port is commonly used for. Enter a port number such as 443 or a service name such as HTTPS, choose TCP, UDP, or Any, and the tool searches its built-in reference list. It also shows whether the port belongs to the well-known, registered, or dynamic/private range.
Network ports range from 0 through 65535. The reference tool divides them into well-known ports from 0–1023, registered ports from 1024–49151, and dynamic/private ports from 49152–65535.
How to Use the Port Checker
Look up a port number
Type a number from 0 through 65535 and select the protocol. If the port is in the built-in common-services table, the page displays the service name and description. If no common service is listed, the tool still shows the correct numerical range for the port.
Search by service name
You can also enter a service such as HTTPS, SSH, DNS, MySQL, PostgreSQL, Redis, RDP, or WireGuard. When a service uses more than one protocol or port, the selected protocol helps narrow the result.
Understand TCP and UDP
TCP is connection-oriented and provides reliable, ordered delivery, while UDP is connectionless and emphasizes low overhead and speed. HTTP, HTTPS, SSH, and many database services commonly use TCP. DNS, DHCP, NTP, VoIP, and many real-time applications commonly use UDP, though some services support both.
Understand well-known ports
Ports 0 through 1023 are commonly called well-known or system ports. Familiar examples include SSH on 22, DNS on 53, HTTP on 80, and HTTPS on 443. These low-numbered ports are associated with standardized core services.
Understand registered ports
Ports 1024 through 49151 are the registered or user range. Many applications and databases operate here, including MySQL on 3306, PostgreSQL on 5432, Redis on 6379, and numerous vendor-specific services.
Understand dynamic and private ports
Ports 49152 through 65535 are commonly used as dynamic or ephemeral ports. Client systems frequently choose temporary source ports from this high range when opening outbound connections.
UDP & TCP Port Lookup Quick Reference
The strongest use of this page is identifying what a UDP or TCP port number is commonly associated with. The protocol selector lets you narrow a lookup to UDP, TCP, or both. Because the page runs as normal browser JavaScript, it does not open raw sockets to remote hosts and therefore does not claim that a remote UDP or TCP port is open or closed.
| Task | What this tool does | Example / limitation |
|---|---|---|
| UDP port checker reference | Select UDP and enter a port number or service name to search the bundled UDP service list. | 53 / UDP → DNS; 123 / UDP → NTP; 51820 / UDP → WireGuard. |
| TCP port lookup | Select TCP to search common TCP service associations. | 22 / TCP → SSH; 443 / TCP → HTTPS. |
| Check a UDP port number | Validates 0–65535, identifies the range, and shows a bundled service match when available. | A valid number with no match is still a valid UDP port number. |
| Search by service | Matches bundled service names and descriptions, then filters by the selected protocol. | Searching DNS with Any returns both TCP and UDP entries. |
| Check whether a port is open | Not performed by this standalone page. | Live reachability requires a network-capable backend, native socket tool, or command-line utility. |
| Check firewall status | Not performed. | A local reference lookup cannot distinguish open, closed, filtered, NAT-blocked, or routed states. |
How to check a UDP port number with this tool
Choose UDP from the Protocol menu, enter a port number from 0 through 65535, and select Look Up. The result shows the numerical range and any matching UDP service in the bundled reference. For example, UDP port 53 is commonly associated with DNS queries, UDP 123 with NTP, and UDP 51820 with WireGuard.
UDP port checker vs. live UDP reachability test
A UDP port reference lookup and a live UDP test are different tasks. This page answers “What is this UDP port commonly used for?” It does not send a UDP datagram to a remote server. UDP also has no TCP-style connection handshake, so a missing response in a real probe can mean many things: the service may be silent, a firewall may drop traffic, routing may fail, or the application may require a specific payload.
How to test a UDP port on a system you manage
This page does not send network packets, but it can help you choose the correct port and protocol before a real connectivity test. On a machine you administer (or have permission to test), a network-capable command-line tool can probe a target. Replace the documentation-only address below with your own authorized host:
# Linux/macOS with Nmap installed — UDP port 123
nmap -sU -p 123 192.0.2.10
# TCP port 443 with Nmap
nmap -sT -p 443 192.0.2.10
# Windows PowerShell — TCP only (not a UDP test)
Test-NetConnection -ComputerName 192.0.2.10 -Port 443
For UDP, open|filtered does not mean the port is confirmed open: a missing UDP reply could indicate an open but silent service or packet filtering. Nmap's UDP scan documentation explains why the result can be ambiguous. Always check the listening process and firewall rules on the system you control, and use a protocol-specific application test where possible.
Example: is port 64660 valid?
Yes. Port 64660 is within the 0–65535 numeric range and belongs to the 49152–65535 dynamic/private range. The bundled list may have no common-service entry for it. That is not evidence that it is closed, unassigned to a local application, or safe to expose. Port 0 is also within the 16-bit numeric range but is reserved for special purposes rather than ordinary destination-service use.
Check port UDP or TCP before troubleshooting
When diagnosing a network service, first confirm the expected port and protocol. A service configured for UDP will not be verified by looking only at its TCP assignment, and vice versa. After confirming the reference information here, test the actual endpoint using a network-capable tool on a system you administer.
Lookup Methodology, Port Ranges, and Important Limits
This page performs a local reference lookup against its bundled list of common TCP and UDP services. It does not query a live IANA registry, scan a host, open a socket, test a firewall, or verify that any process is actually listening on a port.
Worked example: numeric lookup
Query: 443
Protocol: Any
Bundled match:
443 / TCP / HTTPS
Range:
0–1023
→ Well-Known / System
Important:
This identifies the conventional service association.
It does NOT prove that a host is listening on 443.
Worked example: service-name lookup
Query: dns
Protocol: Any
Matches in the bundled table:
53 / TCP / DNS
53 / UDP / DNS
Result:
Port = 53
Protocol = TCP, UDP
Service = DNS
A valid port can still have no common service listed
If you enter a valid number that is not present in the bundled table, the tool still reports its numerical range and marks it as a valid port. “No common service listed” means only that this page's reference table does not contain a matching entry.
Service names are conventional associations, not proof of application identity
Administrators can run services on nonstandard ports, and a process listening on a familiar port can be something other than the conventional service. A lookup result such as HTTPS for 443 or SSH for 22 describes common usage, not the identity of a live process.
TCP and UDP are separate namespaces for lookup purposes
The same port number can have different conventional uses under TCP and UDP. When Protocol is set to Any, the tool can return both. Selecting TCP or UDP narrows the result to entries using that transport.
The service-name search is substring-based
Text queries are checked against both the bundled service name and description using case-insensitive substring matching. A broad term can therefore return several matches, and the result combines unique ports, protocols, service names, and descriptions from all matches.
Multiple service matches can span more than one port
For text searches, the displayed Port field can contain a comma-separated set of matching ports. If multiple matches cover different standard ranges, the result now says “Multiple ranges” and lists the individual port/protocol/service matches.
Unknown text is not the same as an unassigned port
A “No match” result for a service-name query only means the bundled table did not find the text. It does not determine whether IANA has an assignment for that service or whether a product commonly uses that port in practice.
This tool does not perform remote open/closed testing
Normal browser JavaScript cannot create arbitrary raw TCP or UDP socket connections to any host and port. A real reachability test requires a network-capable backend, command-line utility, native application, or another environment with socket access.
Open, closed, and filtered are network-state concepts—not lookup labels
A live port test can produce outcomes influenced by the destination host, firewall policy, routing, NAT, service state, TCP resets, UDP silence, and timeout behavior. This standalone page intentionally avoids presenting any of those states because it does not perform a network probe.
Common mistakes
- Assuming a known port means that service is definitely running.
- Assuming an unknown result means the port is unassigned everywhere.
- Confusing a service lookup with a live open-port test.
- Ignoring the TCP/UDP distinction when troubleshooting.
- Treating dynamic/private ports as automatically suspicious or safe.
Related Utiliverse Tools
Last reviewed: November 6, 2026 · Port validation, TCP/UDP filtering, service-name matching, range classification, bundled common-port behavior, table filtering, no-scan limitation, and theme behavior reviewed against the current implementation.
Practical Uses
Firewall configuration
Before allowing or blocking a port, look up its common service to verify what type of application may be affected. A port number alone does not prove which program is actually listening, but the reference can help identify the conventional use.
Server troubleshooting
If a web server, database, VPN, mail service, or remote-management tool is not reachable, confirming the expected service port is a useful first step before checking firewall rules, NAT, routing, or the actual listening process.
Learning common networking ports
The filterable reference table is useful for students, IT staff, developers, and administrators learning commonly encountered TCP and UDP services.
Security reviews
Open ports represent network entry points, so unnecessary services should generally be disabled or restricted. On systems you administer, minimize unnecessary exposed services, apply appropriate firewall rules, and keep listening services patched.
Why this browser tool does not scan hosts
A normal web page cannot create arbitrary raw TCP or UDP socket connections to any host and port. Browsers intentionally restrict that capability. A true reachability scan requires a server-side probe, command-line tool, native application, browser extension with special permissions, or another network-capable service. This Utiliverse page therefore performs a reliable local port/service lookup rather than displaying invented open/closed results.
Port Checker FAQ
What is a UDP port checker?
On this page, a UDP port checker means a reference lookup for UDP port numbers and common service assignments. It does not send packets to a remote host or determine whether a live UDP port is open.
How do I check a UDP port number?
Select UDP, enter a number from 0 through 65535, and run the lookup. The tool validates the number, shows its standard range, and displays a bundled common-service match when one is available.
Can this tool check whether a UDP port is open?
No. This standalone browser page does not perform remote socket probes. A real UDP reachability test requires a network-capable backend, native application, or command-line utility.
How do I run a real UDP port test?
On a system you administer or have permission to test, a tool such as Nmap can send UDP probes (for example nmap -sU -p 123 192.0.2.10, with your authorized host substituted). An open|filtered result does not confirm that the port is open; verify the actual service and firewall too.
Is port 64660 a valid port number?
Yes. It is within the 0–65535 numeric range and falls in the dynamic/private range of 49152–65535. That classification is not a live-service or firewall-status result.
Why is UDP port checking different from TCP port checking?
TCP has a connection handshake that can provide clearer connection-state feedback. UDP is connectionless, so silence during a real probe can have several causes and does not by itself prove a port is closed.
What port does DNS use?
DNS commonly uses port 53 under both UDP and TCP, depending on the type of DNS traffic.
What port does NTP use?
NTP commonly uses UDP port 123.
What port does WireGuard use by default?
WireGuard commonly uses UDP port 51820 by default, although administrators can configure a different port.
What port does HTTPS use?
HTTPS commonly uses TCP port 443.
What port does SSH use?
SSH commonly uses TCP port 22.
What is the highest valid port number?
Port numbers range from 0 through 65535.
What are ephemeral ports?
They are temporary ports commonly selected by client systems for outbound connections, often from the dynamic/private range of 49152 through 65535.
Does a known port guarantee that service is running?
No. Port assignments describe conventional usage and do not prove which process is listening on a live endpoint.
Is the built-in table the complete IANA port registry?
No. It is a curated list of commonly encountered services. Use the official IANA registry when you need the complete assignment reference.
Can the same port number be used by both TCP and UDP?
Yes. TCP and UDP are separate transport protocols and can both have entries for the same numeric port.
Does this tool tell me whether a firewall is blocking a port?
No. Without a live network probe, it cannot determine open, closed, filtered, routed, NAT-blocked, or firewall-blocked states.
Use a port lookup as a reference, not a connectivity result
Looking up 443 identifies a common HTTPS association. It does not show that a machine is listening, that its certificate is valid, or that a firewall allows access. Specify TCP or UDP when investigating a real endpoint.
A useful troubleshooting sequence
Record the application, hostname, transport and port. Check the configured listener on a system you administer, then routing and firewall policy, then the application response. A timeout or absent UDP reply can have several causes.
This tool uses a bundled common-port table and performs no host scan. An unknown result can mean the reference does not include the service; consult the IANA registry for assignment details. Dynamic/private ports are not inherently safe or unsafe.
Related guides
Related tools
Sources
Lookup behavior and troubleshooting guidance reviewed November 6, 2026. Methodology · Corrections.