Ports 2000–4999

Port 2049 — NFS

At a Glance

• Transport: TCP/UDP

• Common service: Network File System

• Main purpose: Mounts remote storage as local

• Status: Official, current

• Related ports: 111

What It Does

Provides Unix/Linux network file sharing. NFS commonly uses port 2049. NFSv4 clients connect directly to TCP port 2049, while older NFS versions may also depend on RPC services such as rpcbind on port 111.

ELI Explains Magic bookshelf in another room appears in yours. Put a book there — shows up in your classroom. Files feel local.

A 10-Year-Old's Example Shared toy box in hallway. Reach through magic portal from your room, pull out any toy. NFS is that portal.

Remember This NFS presents remote storage to clients. Restrict exports and network access, and use the security features appropriate to the NFS version.

Port 2376 — Docker API (TLS)

At a Glance

• Transport: TCP

• Common service: Docker Remote API (TLS)

• Main purpose: Encrypted container management

• Status: Official, current

• Related ports: 2375

What It Does

Docker API with mutual TLS. Client and server verify certificates. Secure remote container management.

ELI Explains Docker remote with fingerprint scan. Only your print works, lights confirm they're yours. Proper security.

A 10-Year-Old's Example Bedroom light remote with fingerprint — only you control it. Port 2376 is that secure remote. Never use 2375.

Remember This Encrypted Docker management. Always use over unencrypted port 2375.

Port 3000 — Development Web Server

At a Glance

• Transport: TCP

• Common service: Alternate HTTP / Dev

• Main purpose: Web development and testing

• Status: Common convention; not an exclusive assignment

• Related ports: 80, 443, 8080

What It Does

Development servers — Rails, Node.js, React. Test without privileges needed for port 80.

ELI Explains Building a model house in the garage. Test, break, rebuild safely. Perfect? Move to 80 or 443.

A 10-Year-Old's Example LEGO castle on bedroom floor. Try designs, knock down, rebuild. Perfect? Living room. Port 3000 is your floor.

Remember This Common dev server port. For testing before production on 80/443.

Port 3128 — Squid Proxy

At a Glance

• Transport: TCP

• Common service: Squid Web Proxy Cache

• Main purpose: Caches and filters web content

• Status: Common convention; not an exclusive assignment

• Related ports: 8080

What It Does

Caches popular web content for speed. Can filter access. Organizations use it to optimize and control browsing.

ELI Explains Librarian keeps popular books on the front desk. Ask — if there, instant. If not, fetch and keep copy.

A 10-Year-Old's Example Teacher's five most-requested worksheets on her desk. #3? Instant. #27? Get from cabinet, add to desk.

Remember This Squid caches web content. Speeds browsing, can filter access.

Port 3269 — Active Directory Global Catalog (LDAPS)

At a Glance

• Transport: TCP

• Common service: Microsoft Global Catalog (LDAPS)

• Main purpose: Encrypted forest-wide AD searches

• Status: Official, current

• Related ports: 3268, 636

What It Does

Searches entire AD forest over TLS. Protects cross-domain directory queries from eavesdropping.

ELI Explains Master encyclopedia index in a private room. Same searches as 3268, encrypted so nobody reads over your shoulder.

A 10-Year-Old's Example Look up student: 3268 = public kiosk. 3269 = take directory into private study room first.

Remember This Encrypted Global Catalog. Always prefer over port 3268.

Port 3306 — MySQL/MariaDB

At a Glance

• Transport: TCP

• Common service: MySQL Database

• Main purpose: Database connections

• Status: Official, current

• Related ports: None

What It Does

Default MySQL/MariaDB port. Powers WordPress, enterprise apps, web services.

ELI Explains Giant organized warehouse. "File under Users." "Price of item 4527?" Database keeps everything findable.

A 10-Year-Old's Example Card catalog: "dentist's number card." Keeper finds it instantly. Port 3306 is that keeper.

Remember This Default MySQL/MariaDB port. Restrict to app servers, enable TLS.

Security Note Never expose directly to the internet.

Port 3389 — RDP

At a Glance

• Transport: TCP/UDP

• Common service: Remote Desktop Protocol

• Main purpose: Graphical remote desktop to Windows

• Status: Official, current

• Related ports: None

What It Does

Provides a graphical remote Windows session. Modern RDP can use both TCP and UDP on port 3389 and supports encrypted transport, but exposure still requires strong authentication and network controls.

ELI Explains Magic mirror showing another computer's screen — and you control it. Move mouse at home, cursor moves at office.

A 10-Year-Old's Example Robot double at your school desk. Control from tablet at home. Writes what you type, shows you the board.

Remember This RDP: graphical remote desktop. Never expose directly to internet without VPN.

Security Note Frequent brute-force target — use VPN and strong passwords.

Port 4500 — IPsec NAT Traversal

At a Glance

• Transport: UDP

• Common service: IPsec NAT Traversal

• Main purpose: IPsec VPNs through NAT

• Status: Official, current

• Related ports: 500

What It Does

Encapsulates IPsec in UDP to pass through NAT. Square package in round box — works with port 500 IKE.

ELI Explains Square package in round box to fit through round tunnel. Home routers block raw IPsec. Port 4500 disguises it.

A 10-Year-Old's Example Square-wheeled car in round ball through round tunnel. Port 4500 is that ball for VPN traffic.

Remember This Port 4500 enables IPsec through NAT. Works alongside port 500.