Subjects and lessons to explore.

Law

Network+ (N10-009) · ELI Explains Port Numbers (book)

Ports 500–999

5 min read
Report an error
On this page 2 sections
  1. The college version
  2. Study tools

The college version

Port 500 — IKE

At a Glance

  • Transport: UDP
  • Common service: Internet Key Exchange
  • Main purpose: Negotiates IPsec VPN security
  • Status: Official, current
  • Related ports: 4500

What It Does

Negotiates encryption, exchanges keys, authenticates endpoints for IPsec VPNs. The setup phase before encrypted data flows.

ELI Explains Two diplomats meeting to agree on rules before trading. Decide language, locks, exchange codebooks. Then trading begins elsewhere.

A 10-Year-Old's Example Before building a clubhouse, meet to agree on secret knock and password. Port 500 is that planning meeting.

Remember This Port 500 handles IPsec VPN key exchange — setup before encrypted tunnels form.

Port 514 — Syslog

At a Glance

  • Transport: UDP
  • Common service: Syslog
  • Main purpose: Centralized log collection
  • Status: Official, current
  • Related ports: 6514

What It Does

Collects log messages from devices, servers, and apps into one repository. Essential for monitoring and troubleshooting.

ELI Explains Every teacher sends daily notes to one filing clerk. Principal visits one office instead of 50 classrooms. Syslog gathers all reports.

A 10-Year-Old's Example Students write one thing that happened on a slip, drop in a box. Syslog is that box for computers.

Remember This Syslog collects logs centrally. Use TLS on port 6514 for secure transmission.

Port 587 — SMTP Submission

At a Glance

  • Transport: TCP
  • Common service: SMTP Mail Submission
  • Main purpose: Authenticated email submission
  • Status: Official, current
  • Related ports: 25, 465

What It Does

The standard message-submission port. Providers commonly require authentication and require or offer STARTTLS. It separates client submission from server-to-server relay on port 25.

ELI Explains "Authorized senders only" drop box. Show ID before dropping mail. Port 25 is the loading dock; 587 is the customer counter.

A 10-Year-Old's Example Delivery entrance (25) vs. office where you hand a permission slip to the secretary (587). Student entrance — authenticated.

Remember This Port 587 is the standard submission port, commonly paired with authentication and STARTTLS. Port 465 is also standardized for submission over implicit TLS.

Port 631 — IPP

At a Glance

  • Transport: TCP
  • Common service: Internet Printing Protocol
  • Main purpose: Modern network printing
  • Status: Official, current
  • Related ports: None

What It Does

Carries Internet Printing Protocol requests, normally over HTTP on TCP. IPP supports job submission and status; IPP over HTTPS adds TLS. It is used by CUPS and AirPrint.

ELI Explains Print job with tracking: "Job #42, page 3 of 10, enough paper." Status updates, cancel anytime. Old way: hope it printed.

A 10-Year-Old's Example Hand homework to a helper: "Ready in 2 minutes — I'll let you know." IPP is that helper, not a dark chute.

Remember This IPP on port 631 is modern printing — used by CUPS and AirPrint.

Port 636 — LDAPS

At a Glance

  • Transport: TCP
  • Common service: LDAP over SSL/TLS
  • Main purpose: Encrypted directory queries
  • Status: Official, current
  • Related ports: 389

What It Does

Carries LDAP over implicit TLS. LDAP can also be protected by negotiating StartTLS on port 389. In either case, certificate validation and directory policy matter.

ELI Explains A private directory room. Port 636 locks the door immediately; port 389 can also lock it after a StartTLS upgrade.

A 10-Year-Old's Example Ask for locker combo: old way is out loud in hallway. 636: secretary leads you into private office first.

Remember This Protect LDAP with TLS, either through LDAPS on port 636 or StartTLS on port 389.

Port 989 — Implicit FTPS Data (Legacy)

At a Glance

  • Transport: TCP
  • Common service: Implicit FTPS Data
  • Main purpose: Legacy implicit-TLS FTP data
  • Status: Official, legacy implicit FTPS
  • Related ports: 20, 990

What It Does

Port 989 is assigned to the data channel for implicit FTPS, a legacy deployment model. Modern explicit FTPS upgrades a port 21 control session with TLS and negotiates data ports. FTPS is distinct from SFTP over SSH.

ELI Explains Armored truck for FTP delivery. Regular FTP: regular van. FTPS: same files in armored truck, lock only recipient opens.

A 10-Year-Old's Example Send a present: FTP = clear bag. FTPS = same present in sealed box. Same delivery, private.

Remember This Port 989 belongs to legacy implicit FTPS data. Explicit FTPS normally starts on port 21; SFTP uses SSH on port 22.

Port 990 — Implicit FTPS Control (Legacy)

At a Glance

  • Transport: TCP
  • Common service: Implicit FTPS Control
  • Main purpose: Legacy implicit-TLS FTP control
  • Status: Official, legacy implicit FTPS
  • Related ports: 21, 989

What It Does

Port 990 is assigned to the control channel for implicit FTPS, a legacy deployment model. Modern explicit FTPS normally starts on port 21 and upgrades the session with TLS.

ELI Explains Secure front desk. Port 21: say your password out loud. Port 990: soundproof glass, secure intercom. Same conversation, private.

A 10-Year-Old's Example Video store: "password is dragon123" in crowded store (21). Private booths where you whisper (990). Much safer.

Remember This Port 990 is the legacy implicit-FTPS control port. Explicit FTPS normally upgrades a port 21 session with TLS.

Port 993 — IMAPS

At a Glance

  • Transport: TCP
  • Common service: IMAP over SSL/TLS
  • Main purpose: Encrypted multi-device email
  • Status: Official, current
  • Related ports: 143

What It Does

IMAP + TLS. Multi-device sync with credentials and content protected. The secure standard for modern email.

ELI Explains Reading mail in a private room instead of a public table. Same sync as IMAP, but locked door. Nobody peeks.

A 10-Year-Old's Example Diary on shelf: IMAP = door open. IMAPS = door locked so brother can't peek.

Remember This IMAPS encrypts multi-device email. Always prefer over plaintext IMAP.

Port 995 — POP3S

At a Glance

  • Transport: TCP
  • Common service: POP3 over SSL/TLS
  • Main purpose: Encrypted email download
  • Status: Official, current
  • Related ports: 110

What It Does

Provides POP3 over implicit TLS. It protects credentials and mail in transit; whether messages remain on the server depends on client settings and server policy.

ELI Explains Locked mailbox. POP3: open bin. POP3S: same bin needs a key only you and the clerk have.

A 10-Year-Old's Example Cubby homework: POP3 = open. POP3S = cubby with combination lock. Multi-device? Use IMAPS (993).

Remember This Port 995 provides POP3 over implicit TLS. For server-based multi-device synchronization, use IMAP over TLS on port 993.

Keep learning

Ready to build on this? Continue to the next lesson.

Practice Network+ (N10-009)

This lesson has no separate scored set. Practice draws from the subject’s question bank.

Study tools & related lessonsRelated

Educational content only. It is not medical, legal or professional advice. Found an error? Tell us.