TCP/UDP Port Reference
Search 90+ well-known ports by number, service, or category
56 of 56 ports shown
| Port | Protocol | Service |
|---|---|---|
| 20 | TCP | FTP-Data |
| 21 | TCP | FTP |
| 22 | TCP | SSH |
| 23 | TCP | Telnet |
| 25 | TCP | SMTP |
| 53 | TCP/UDP | DNS |
| 67 | UDP | DHCP Server |
| 68 | UDP | DHCP Client |
| 69 | UDP | TFTP |
| 80 | TCP | HTTP |
| 88 | TCP/UDP | Kerberos |
| 110 | TCP | POP3 |
| 119 | TCP | NNTP |
| 123 | UDP | NTP |
| 135 | TCP/UDP | MS-RPC |
| 137 | UDP | NetBIOS-NS |
| 138 | UDP | NetBIOS-DGM |
| 139 | TCP | NetBIOS-SSN |
| 143 | TCP | IMAP |
| 161 | UDP | SNMP |
| 162 | UDP | SNMP Trap |
| 179 | TCP | BGP |
| 389 | TCP/UDP | LDAP |
| 443 | TCP | HTTPS |
| 445 | TCP | SMB |
| 465 | TCP | SMTPS |
| 500 | UDP | IKE / ISAKMP |
| 514 | UDP | Syslog |
| 515 | TCP | LPD/LPR |
| 587 | TCP | SMTP Submission |
| 636 | TCP | LDAPS |
| 993 | TCP | IMAPS |
| 995 | TCP | POP3S |
| 1194 | UDP | OpenVPN |
| 1433 | TCP | MS-SQL |
| 1434 | UDP | MS-SQL Browser |
| 1521 | TCP | Oracle DB |
| 1701 | UDP | L2TP |
| 1723 | TCP | PPTP |
| 1812 | UDP | RADIUS Auth |
| 1813 | UDP | RADIUS Accounting |
| 2049 | TCP/UDP | NFS |
| 3074 | TCP/UDP | Xbox Live |
| 3306 | TCP | MySQL |
| 3389 | TCP | RDP |
| 3690 | TCP | SVN |
| 4500 | UDP | IPsec NAT-T |
| 5060 | TCP/UDP | SIP |
| 5061 | TCP | SIPS |
| 5432 | TCP | PostgreSQL |
| 5900 | TCP | VNC |
| 6443 | TCP | Kubernetes API |
| 8080 | TCP | HTTP Alt |
| 8443 | TCP | HTTPS Alt |
| 9200 | TCP | Elasticsearch |
| 27017 | TCP | MongoDB |
Key port ranges to memorise
0–1023
Well-known ports
Assigned by IANA to standard services (HTTP, SSH, DNS, etc.)
1024–49151
Registered ports
Assigned to specific applications by IANA (databases, messaging, etc.)
49152–65535
Dynamic/ephemeral
Used by OS for temporary client-side connections
Frequently asked questions
What is the difference between TCP and UDP ports?
TCP (Transmission Control Protocol) is connection-oriented — it establishes a session, guarantees delivery, and checks for errors. UDP (User Datagram Protocol) is connectionless — it sends data without establishing a session, so it is faster but unreliable. Many services use both (e.g., DNS uses UDP for queries and TCP for zone transfers).
What are well-known ports?
Well-known ports are in the range 0–1023 and are assigned by IANA to standard services. Ports 1024–49151 are registered ports assigned to specific applications. Ports 49152–65535 are dynamic/ephemeral ports used by clients for temporary connections.
Why does DNS use both TCP and UDP port 53?
DNS uses UDP port 53 for standard queries because they are small and speed matters. DNS uses TCP port 53 when the response is too large for a UDP packet (over 512 bytes), or for zone transfers (AXFR) between DNS servers.
What is the difference between IMAP and POP3?
POP3 (port 110/995) downloads emails to a local device and typically deletes them from the server. IMAP (port 143/993) synchronises emails and keeps them on the server, allowing access from multiple devices. IMAP is preferred for modern multi-device use.
Why should Telnet (port 23) be avoided?
Telnet transmits all data — including credentials — in plaintext. Anyone with network access can capture the traffic and read usernames and passwords. SSH (port 22) provides the same remote access functionality with strong encryption and should always be used instead.