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A quick-reference cheat sheet for standard TCP and UDP port numbers, well-known internet protocols, default service ports, and firewall port forwarding rules.
Run live checks and calculations directly on LotsofNetwork.
Network ports range from 1 to 65535 and are categorized into three standardized tiers defined by the Internet Assigned Numbers Authority (IANA):
1. Well-Known Ports (0 – 1023): Reserved for privileged core operating system services, HTTP, SSH, FTP, and DNS.
2. Registered Ports (1024 – 49151): Assigned to specific vendor applications, databases, and enterprise services (e.g. MySQL 3306, RDP 3389).
3. Dynamic / Private / Ephemeral Ports (49152 – 65535): Temporarily assigned by client operating systems for outgoing connection endpoints.
Here are the most common network ports encountered by sysadmins, developers, and security engineers daily:
Port Protocol Service / Application Default Security Recommendation 20/21 TCP FTP (File Transfer) Deprecated. Use SFTP (Port 22) instead. 22 TCP SSH / SFTP Enforce SSH keys, disable root password login. 23 TCP Telnet (Cleartext terminal) Insecure. Block at firewall; replace with SSH. 25 TCP SMTP (Server Mail Routing) Filter outbound port 25 to prevent spam abuse. 53 TCP/UDP DNS (Domain Name System) UDP for queries under 512B; TCP for zone transfers. 80 TCP HTTP (Web Traffic) Redirect permanently (301) to HTTPS Port 443. 110 TCP POP3 (Email Retrieval) Use POP3S (Port 995 with SSL/TLS). 123 UDP NTP (Network Time Protocol) Critical for clock synchronization and TLS validity. 143 TCP IMAP (Email Retrieval) Use IMAPS (Port 993 with SSL/TLS). 443 TCP HTTPS (Encrypted Web) Standard modern web service port with TLS. 445 TCP SMB (Windows File Sharing) NEVER expose to the public internet (Ransomware risk). 3306 TCP MySQL / MariaDB Bind to 127.0.0.1; access via SSH tunnel or private VPN. 3389 TCP/UDP RDP (Windows Remote Desktop) Do NOT expose directly. Use VPN or RD Gateway. 5432 TCP PostgreSQL Database Isolate in private subnet; enforce TLS client certificates. 6379 TCP Redis In-Memory Store No built-in encryption by default. Bind to localhost. 8080 TCP HTTP Alternate / Proxy Commonly used for Tomcat, Spring, and Dev web servers.
Verifying whether a port is open to the public internet helps validate firewall configurations, NAT port forwarding, and application deployments.
You can test any public IP or domain name instantly using our free Port Checker tool without installing command line utilities.
AI Mobile App Developer & Full-Stack Systems Engineer•Dhaka, Bangladesh
Bayajit Islam is an AI Mobile App Developer and Full-Stack Systems Engineer based in Dhaka, Bangladesh. With 2+ years of hands-on production experience building cross-platform apps for iOS, Android & Desktop with Flutter & Dart, asynchronous backends with FastAPI & Python, and modern web applications with Next.js, TypeScript, and Docker, he engineered LotsofNetwork as a zero-latency, privacy-first diagnostic platform for developers and network administrators.
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