Port Number Lookup

Search common TCP and UDP ports by number or service. Each port page explains what uses it, whether it is safe to expose to the internet, and gives commands to check what is listening and to open or block it in a firewall.

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Port	Protocol	Service	What it is	Exposure
20	TCP	FTP data	The data channel of FTP in active mode	Restrict
21	TCP	FTP	The control port of FTP, the File Transfer Protocol	Restrict
22	TCP	SSH	Used by SSH for secure remote logins, SFTP, SCP and Git over SSH	Restrict
23	TCP	Telnet	Used by Telnet, an old unencrypted remote terminal protocol	Private
25	TCP	SMTP	Used by SMTP for delivering email between mail servers	Public
53	UDP/TCP	DNS	Used by DNS to translate domain names into IP addresses	Restrict
67	UDP	DHCP server	Where DHCP servers listen for requests from devices that need an IP address	Private
68	UDP	DHCP client	The port DHCP clients use to receive IP address offers	Private
69	UDP	TFTP	Used by TFTP, a minimal file transfer protocol for network booting and device firmware	Private
80	TCP	HTTP	The default port for HTTP, unencrypted web traffic	Public
88	TCP/UDP	Kerberos	Used by Kerberos authentication, including Active Directory logins	Private
110	TCP	POP3	Used by POP3 for downloading email from a mail server	Restrict
123	UDP	NTP	Used by NTP, the Network Time Protocol, to keep clocks in sync	Restrict
135	TCP	Microsoft RPC	The Microsoft RPC endpoint mapper, used by many Windows services	Private
139	TCP	NetBIOS Session	Used by NetBIOS session service, the legacy transport for Windows file sharing	Private
137	UDP	NetBIOS Name Service	Used by NetBIOS name service for legacy Windows name resolution on local networks	Private
143	TCP	IMAP	Used by IMAP for reading email that stays on the server	Restrict
161	UDP	SNMP	Used by SNMP for monitoring and managing network devices	Private
162	UDP	SNMP traps	Where SNMP managers receive traps (alerts) sent by devices	Private
179	TCP	BGP	Used by BGP, the routing protocol that connects networks on the internet	Restrict
389	TCP/UDP	LDAP	Used by LDAP for directory lookups and authentication, including Active Directory	Private
443	TCP/UDP	HTTPS	The default port for HTTPS, encrypted web traffic	Public
445	TCP	SMB	Used by SMB for Windows file and printer sharing	Private
465	TCP	SMTPS	Used for email submission over implicit TLS (SMTPS)	Public
514	UDP/TCP	Syslog	Used by syslog for sending log messages to a central server	Private
587	TCP	SMTP submission	The standard port for sending email from apps and mail clients	Public
636	TCP	LDAPS	Used by LDAP over TLS (LDAPS) for encrypted directory access	Private
853	TCP	DNS over TLS	Used by DNS over TLS (DoT) for encrypted DNS queries	Public
873	TCP	rsync	Used by the rsync daemon for file synchronization	Restrict
990	TCP	FTPS	Used by FTPS in implicit TLS mode	Restrict
993	TCP	IMAPS	Used by IMAP over TLS for securely reading email	Public
995	TCP	POP3S	Used by POP3 over TLS for securely downloading email	Public
1080	TCP	SOCKS proxy	The conventional port for SOCKS proxies	Private
1194	UDP/TCP	OpenVPN	The default port for OpenVPN	Public
1433	TCP	Microsoft SQL Server	The default port for Microsoft SQL Server	Private
1434	UDP	SQL Server Browser	Used by the SQL Server Browser service to locate named instances	Private
1521	TCP	Oracle Database	The default port for the Oracle Database listener	Private
1812	UDP	RADIUS	Used by RADIUS for network access authentication	Private
1883	TCP	MQTT	The default port for MQTT, the publish/subscribe protocol for IoT	Private
2049	TCP/UDP	NFS	Used by NFS, the Network File System	Private
2222	TCP	SSH (alternate)	A common alternate port for SSH	Restrict
2375	TCP	Docker API (unencrypted)	The Docker daemon API without TLS	Private
2376	TCP	Docker API (TLS)	The Docker daemon API secured with TLS	Restrict
2379	TCP	etcd client	The etcd client API port, used by the Kubernetes API server	Private
2380	TCP	etcd peer	Used for replication between etcd cluster members	Private
3000	TCP	Development server / Grafana	The default port of many development servers and of Grafana	Restrict
3128	TCP	Squid proxy	The default port of the Squid HTTP proxy	Private
3268	TCP	Active Directory Global Catalog	Used by the Active Directory Global Catalog for forest-wide LDAP searches	Private
3269	TCP	Global Catalog over TLS	Used by the Active Directory Global Catalog over TLS	Private
3306	TCP	MySQL / MariaDB	The default port for MySQL and MariaDB	Private
3389	TCP/UDP	RDP	Used by RDP, Microsoft’s Remote Desktop Protocol	Restrict
3478	UDP/TCP	STUN / TURN	Used by STUN and TURN servers for WebRTC and VoIP NAT traversal	Public
4222	TCP	NATS	The client port of the NATS messaging system	Private
4317	TCP	OpenTelemetry (OTLP gRPC)	Used by OpenTelemetry to send traces, metrics and logs over gRPC (OTLP)	Private
4318	TCP	OpenTelemetry (OTLP HTTP)	Used by OpenTelemetry to send traces, metrics and logs over HTTP (OTLP)	Private
4369	TCP	Erlang Port Mapper (epmd)	Used by epmd, which lets Erlang nodes such as RabbitMQ find each other	Private
4200	TCP	Angular dev server	The default port of the Angular CLI development server	Private
5000	TCP	Flask / development servers	The default port of the Flask development server and several other tools	Private
5060	UDP/TCP	SIP	Used by SIP for setting up VoIP calls	Restrict
5173	TCP	Vite dev server	The default port of the Vite development server	Private
5222	TCP	XMPP client	Used by XMPP (Jabber) clients to connect to chat servers	Public
5353	UDP	mDNS	Used by multicast DNS for discovering devices on a local network	Private
5432	TCP	PostgreSQL	The default port for PostgreSQL	Private
5601	TCP	Kibana	The default port of Kibana, the Elasticsearch dashboard	Restrict
5672	TCP	AMQP (RabbitMQ)	The AMQP port used by RabbitMQ and other message brokers	Private
5900	TCP	VNC	Used by VNC for remote desktop access	Private
5985	TCP	WinRM (HTTP)	Used by Windows Remote Management over HTTP, including PowerShell remoting	Private
5986	TCP	WinRM (HTTPS)	Used by Windows Remote Management over HTTPS	Restrict
6379	TCP	Redis	The default port for Redis and Valkey	Private
6443	TCP	Kubernetes API server	The default port of the Kubernetes API server	Restrict
7000	TCP	AirPlay (macOS) / Cassandra	Used by the macOS AirPlay Receiver and by Cassandra inter-node traffic	Private
8000	TCP	Development server (Django, Python)	A common port for development servers, including Django and Python’s http.server	Restrict
8080	TCP	HTTP alternate	The most common alternate HTTP port, used by proxies, app servers and dev tools	Restrict
8086	TCP	InfluxDB	The default HTTP API port of InfluxDB	Private
8443	TCP	HTTPS alternate	A common alternate HTTPS port	Restrict
8883	TCP	MQTT over TLS	The port for MQTT secured with TLS	Public
8888	TCP	Jupyter	The default port of Jupyter Notebook and JupyterLab	Private
9000	TCP	PHP-FPM / MinIO / SonarQube	A busy default port: PHP-FPM, MinIO, SonarQube and Portainer all use it	Private
9042	TCP	Cassandra / ScyllaDB	The CQL client port of Apache Cassandra and ScyllaDB	Private
9090	TCP	Prometheus	The default port of the Prometheus server	Restrict
9092	TCP	Apache Kafka	The default broker port of Apache Kafka	Private
9093	TCP	Alertmanager / Kafka controller	Used by Prometheus Alertmanager and often by Kafka KRaft controllers	Private
9100	TCP	Node exporter / printing	Used by Prometheus node_exporter and by raw network printing (JetDirect)	Private
9200	TCP	Elasticsearch / OpenSearch	The HTTP API port of Elasticsearch and OpenSearch	Private
9300	TCP	Elasticsearch transport	Used for communication between Elasticsearch nodes	Private
9418	TCP	Git protocol	Used by the native git:// protocol	Public
10250	TCP	Kubelet API	The kubelet API on every Kubernetes node	Private
11211	TCP/UDP	Memcached	The default port for Memcached	Private
15672	TCP	RabbitMQ management	The web UI and HTTP API of the RabbitMQ management plugin	Restrict
25565	TCP	Minecraft	The default port for Minecraft Java Edition servers	Public
27017	TCP	MongoDB	The default port for MongoDB	Private
51820	UDP	WireGuard	The default port for WireGuard VPNs	Public

Port ranges

Range	Name	Used for
0–1023	Well-known (system) ports	Core internet services: 22 SSH, 53 DNS, 80 HTTP, 443 HTTPS
1024–49151	Registered (user) ports	Applications and databases: 3306 MySQL, 5432 PostgreSQL, 6379 Redis
49152–65535	Dynamic / private / ephemeral	Temporary source ports for outgoing connections

List open ports on a machine

Linux

sudo ss -tulpn             # all listening TCP and UDP sockets with processes

macOS

sudo lsof -nP -iTCP -sTCP:LISTEN
sudo lsof -nP -iUDP

Windows (PowerShell)

Get-NetTCPConnection -State Listen | Sort-Object LocalPort
netstat -ano

Scan another host you own (nmap)

nmap -sT -p 1-1024 192.168.1.10      # TCP connect scan of the first 1024 ports
nmap -sU -p 53,123,161 192.168.1.10   # UDP needs root and is slow

Only scan machines you own or have permission to test. Working out which addresses a firewall rule covers? The CIDR calculator shows the range of any subnet like 10.0.0.0/8.

Frequently asked questions

What is a port number?

An IP address identifies a machine; a port number (0 to 65535) identifies a service on it. A web server listens on port 443 and a database on 5432 on the same IP, and the operating system delivers each incoming connection to the program bound to that port. TCP and UDP have separate port spaces, so TCP 53 and UDP 53 are different.

What are well-known, registered and dynamic ports?

IANA divides ports into three ranges. Well-known ports (0–1023) are assigned to core services like SSH, HTTP and DNS, and need root to bind on Linux and macOS. Registered ports (1024–49151) are assigned on request to applications such as MySQL (3306) and PostgreSQL (5432). Dynamic ports (49152–65535) are never assigned and are used for temporary client-side connections.

Which ports should be open on a web server?

Usually only 443 (HTTPS, TCP and UDP for HTTP/3) and 80 (to redirect to HTTPS and for certificate validation) to everyone, plus 22 (SSH) restricted to your IP or VPN. Databases, caches, message queues and admin dashboards should listen on a private network or localhost, not the public interface.

How do I see which ports are open on my computer?

On Linux, run sudo ss -tulpn. On macOS, run sudo lsof -nP -iTCP -sTCP:LISTEN for TCP and sudo lsof -nP -iUDP for UDP. On Windows, run netstat -ano in a terminal, or Get-NetTCPConnection -State Listen in PowerShell. Each shows the port, the address it listens on and the process ID.

Does changing a service’s port make it more secure?

Only slightly. Moving SSH from 22 to another port cuts down log noise from bots, but scanners like Shodan and masscan find services on any port within hours. Real protection comes from authentication, keeping software updated and firewalling the port to the networks that need it.