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Developer Network Port & Service Reference

Interactive developer reference for well-known, registered, and dynamic TCP/UDP network ports (0–65535). Search by port number or service name (SSH, HTTPS, Postgres, Redis, Kafka) to inspect transport protocols, RFC specifications, attack vectors, and firewall hardening advice.

Network Port & Service Reference Search

:20TCP

High Risk

FTP Data

File Transfer Protocol (FTP) data transfer channel.

Hardening: Disable unencrypted FTP; enforce SFTP (SSH) or FTPS (TLS).

:21TCP

High Risk

FTP Control

File Transfer Protocol (FTP) command control channel.

Hardening: Unencrypted credentials. Replace with SFTP over port 22.

:22TCP

Medium Risk

SSH / SFTP

Secure Shell (SSH) for secure command line access and SFTP file transfers.

Spec: RFC 4251

Hardening: Disable root login, enforce SSH keys instead of passwords, use Fail2ban.

:23TCP

Critical Risk

Telnet

Unencrypted text communications for remote terminal access.

Hardening: Legacy protocol transmitting plain-text passwords. Block and use SSH (22).

:25TCP

Medium Risk

SMTP

Simple Mail Transfer Protocol for server-to-server email routing.

Spec: RFC 5321

Hardening: Require STARTTLS, enforce SPF/DKIM/DMARC records.

:53TCP/UDP

Medium Risk

DNS

Domain Name System resolution (UDP for queries, TCP for zone transfers).

Spec: RFC 1035

Hardening: Disable open recursive resolvers to prevent DNS amplification attacks.

:80TCP

Medium Risk

HTTP

Hypertext Transfer Protocol for unencrypted web traffic.

Spec: RFC 7230

Hardening: Redirect all HTTP traffic to HTTPS (port 443) with 301 Permanent Redirect.

:110TCP

High Risk

POP3

Post Office Protocol version 3 for retrieving email messages.

Hardening: Use POP3S over TLS on port 995 instead.

:123UDP

Medium Risk

NTP

Network Time Protocol for clock synchronization across system servers.

Spec: RFC 5905

Hardening: Restrict NTP control queries (`noquery` directive) to block amplification vectors.

:143TCP

Medium Risk

IMAP

Internet Message Access Protocol for mail retrieval and sync.

Hardening: Enforce IMAPS over TLS on port 993.

:443TCP

Low Risk

HTTPS

HTTP Secure over TLS/SSL encryption for web applications and APIs.

Spec: RFC 8446

Hardening: Use TLS 1.2/1.3, configure modern cipher suites, enforce HSTS headers.

:465TCP

Low Risk

SMTPS

SMTP over implicit TLS for secure email submission.

Hardening: Preferred port for secure client mail submission.

:1433TCP

High Risk

MS SQL Server

Microsoft SQL Server relational database engine port.

Hardening: Do not expose directly to public internet; restrict to internal VPC CIDRs.

:3306TCP

High Risk

MySQL / MariaDB

MySQL and MariaDB default relational database connectivity port.

Hardening: Bind `127.0.0.1` locally or restrict ingress to application security groups.

:3389TCP/UDP

Critical Risk

RDP

Microsoft Remote Desktop Protocol for graphical Windows server administration.

Hardening: Frequent target for brute-force attacks. Require VPN or SSH tunnel.

:5432TCP

High Risk

PostgreSQL

PostgreSQL object-relational database default listener port.

Hardening: Enforce `sslmode=require` and restrict host access via `pg_hba.conf`.

:6379TCP

Critical Risk

Redis

Redis in-memory key-value cache and data structure store.

Hardening: Redis has no default auth. Set strong password (`requirepass`) and bind locally.

:8080TCP

Medium Risk

HTTP Alternate / Proxy

Alternative HTTP web server port, common for Tomcat, Spring, and proxies.

Hardening: Protect admin interfaces behind authenticated reverse proxies (Nginx/Envoy).

:8443TCP

Low Risk

HTTPS Alternate

Alternative HTTPS web server listener or management console port.

Hardening: Ensure valid TLS certificates are installed.

:9092TCP

High Risk

Apache Kafka

Apache Kafka distributed event streaming platform broker port.

Hardening: Enable SASL/PLAIN or Mutual TLS (mTLS) authentication for client brokers.

:27017TCP

Critical Risk

MongoDB

MongoDB NoSQL document database listener port.

Hardening: Enable auth immediately (`security.authorization: enabled`) and bind to private IPs.

How to use

Type a port number (e.g. 22, 80, 443, 5432, 6379), service name (SSH, HTTPS, Postgres), or keyword into the search bar.
Filter ports by transport protocol (TCP, UDP, or Both) or functional category (Web, Database, DevOps, Remote Access).
Inspect the port's standard service protocol, security risks, common attack vectors, and hardening recommendations.
Copy port configurations or RFC standards for firewall rule design.

Understanding the output

Network ports (0–65535) route network traffic to specific software processes. Ports 0–1023 are Well-Known System Ports, 1024–49151 are Registered User Ports, and 49152–65535 are Dynamic/Private Ports.

Common issues & tips

•Leaving database ports (5432 PostgreSQL, 3306 MySQL, 6379 Redis) open to 0.0.0.0/0 without TLS or SSH tunneling.
•Confusing TCP and UDP transport behavior: TCP is connection-oriented, whereas UDP is connectionless.

Frequently asked questions

What is the difference between Well-Known, Registered, and Dynamic ports?: Ports 0–1023 are Well-Known (reserved for system services like HTTP/SSH), 1024–49151 are Registered, and 49152–65535 are Dynamic/Ephemeral.

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