Common Port Numbers
A searchable list of the ports developers and sysadmins meet: SSH, HTTP, mail, DNS, databases, caches, queues, Kubernetes, Docker and local dev servers.
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Reference
Common port numbers
| Port | Protocol | Service | Notes |
|---|---|---|---|
| 20, 21 | TCP | FTP | Data and control. Plain text; use SFTP (22) instead. |
| 22 | TCP | SSH, SFTP, scp | The one port to restrict by source IP. |
| 23 | TCP | Telnet | Unencrypted. Should be closed everywhere. |
| 25 | TCP | SMTP (server to server) | Mail relay between servers. Most cloud providers block it outbound by default. |
| 53 | TCP/UDP | DNS | UDP for most queries, TCP for large responses and zone transfers. |
| 67, 68 | UDP | DHCP | Server and client. |
| 80 | TCP | HTTP | |
| 110 | TCP | POP3 | Plain; 995 is POP3 over TLS. |
| 123 | UDP | NTP | Clock sync. Drift breaks TOTP, JWT expiry checks and TLS. |
| 143 | TCP | IMAP | Plain or STARTTLS; 993 is implicit TLS. |
| 161, 162 | UDP | SNMP | Polling and traps. |
| 389 | TCP | LDAP | 636 is LDAP over TLS. |
| 443 | TCP/UDP | HTTPS | UDP 443 carries HTTP/3 (QUIC). |
| 445 | TCP | SMB | Windows file sharing. Never expose it to the internet. |
| 465 | TCP | SMTP submission, implicit TLS | Preferred over 587 by RFC 8314. |
| 514 | UDP | syslog | Remote logging. |
| 587 | TCP | SMTP submission, STARTTLS | Where an app sends mail through a provider. |
| 636 | TCP | LDAPS | |
| 853 | TCP | DNS over TLS | |
| 873 | TCP | rsync daemon | rsync over SSH uses 22 instead. |
| 993 | TCP | IMAPS | |
| 995 | TCP | POP3S | |
| 1025 | TCP | Mailpit / MailHog SMTP | Local mail catcher (default). |
| 1194 | UDP | OpenVPN | |
| 1433 | TCP | Microsoft SQL Server | |
| 1521 | TCP | Oracle Database listener | |
| 1883 | TCP | MQTT | 8883 is MQTT over TLS. |
| 2049 | TCP/UDP | NFS | |
| 2181 | TCP | ZooKeeper | |
| 2375 | TCP | Docker API, no TLS | Exposing it is equivalent to giving away root. |
| 2376 | TCP | Docker API, TLS | |
| 2379, 2380 | TCP | etcd | Client and peer traffic. |
| 3000 | TCP | Grafana; Node and Rails dev servers | Convention, not a standard. |
| 3306 | TCP | MySQL, MariaDB | Bind to 127.0.0.1 or a private network. |
| 3389 | TCP | Remote Desktop (RDP) | |
| 4317, 4318 | TCP | OpenTelemetry OTLP | gRPC and HTTP. |
| 5173 | TCP | Vite dev server | |
| 5353 | UDP | mDNS | Bonjour, .local names. |
| 5432 | TCP | PostgreSQL | |
| 5601 | TCP | Kibana | |
| 5672 | TCP | AMQP (RabbitMQ) | 5671 with TLS; 15672 is the management UI. |
| 6379 | TCP | Redis, Valkey | No auth by default on old versions. Never public. |
| 6432 | TCP | PgBouncer | Default listen port. |
| 6443 | TCP | Kubernetes API server | |
| 6081, 6082 | TCP | Varnish | Default HTTP listener and management interface. |
| 7700 | TCP | Meilisearch | |
| 8000 | TCP | php artisan serve, Django dev server | |
| 8025 | TCP | Mailpit / MailHog web UI | |
| 8080 | TCP | HTTP alternate | Proxies, Tomcat, Jenkins, Laravel Reverb's default. |
| 8108 | TCP | Typesense | |
| 8200 | TCP | HashiCorp Vault | |
| 8443 | TCP | HTTPS alternate | |
| 8500 | TCP | Consul HTTP API | |
| 9000 | TCP | PHP-FPM (FastCGI); MinIO API | PHP-FPM listens here in most Docker images. |
| 9090 | TCP | Prometheus | 9093 Alertmanager, 9100 node_exporter. |
| 9092 | TCP | Kafka | |
| 9200, 9300 | TCP | Elasticsearch, OpenSearch | HTTP API and node transport. |
| 9418 | TCP | Git protocol | Read-only, unauthenticated. |
| 10250 | TCP | Kubelet API | |
| 11211 | TCP | Memcached | Used in UDP amplification attacks; disable UDP. |
| 16686 | TCP | Jaeger UI | |
| 27017 | TCP | MongoDB | |
| 51820 | UDP | WireGuard | Default; configurable. |
Well-known ports (0-1023) are assigned by IANA and need root to bind on Linux; ports above 1023 used by developer tools are conventions. A port being listed here says nothing about whether it should be reachable from the internet.
About this tool
Method, assumptions, practical next steps, and limits.
Assigned and conventional
Ports 0 to 1023 are well-known ports assigned by IANA, and binding to them on Linux needs root or the CAP_NET_BIND_SERVICE capability. Higher ports in this list are registered or simply conventional: Vite's 5173 and Laravel's 8000 are defaults, not standards. The authoritative list is the IANA service name and port number registry.
What should be public
On an internet-facing server, usually only 80 and 443, and 22 restricted to known addresses. Databases, Redis, Memcached, Elasticsearch and the Docker API have all been mass-exploited when exposed. ss -tlnp shows what is listening and on which address.