Network+ Ports

FTP (File Transfer Protocol)

- Ports 20 (data) and 21 (control/commands)
- Transfers files: upload, download, delete, manage
- Insecure: no encryption, even for credentials
- Secure alternative: SFTP (22)

SSH (Secure Shell)

- Port 22
- Secure remote login over an unsecured network
- Encrypts all traffic, including passwords
- Also: file transfer (SCP, SFTP), port forwarding
- Replaces Telnet

SFTP (Secure File Transfer Protocol)

- Port 22 (runs over SSH)
- Secure file transfer, access, and management
- All data and commands encrypted; replaces FTP

Telnet

- Port 23
- Text-based remote terminal connection
- Insecure: plaintext, including logins
- Replaced by SSH

SMTP (Simple/Send Mail Transfer Protocol)

- Port 25
- Sends email: client to server, server to server
- Secure version: SMTPS / SMTP TLS on 587

DNS (Domain Name System)

- Port 53, TCP or UDP
- Translates domain names to IP addresses
- Secure options: DoH (DNS over HTTPS), DoT (DNS over TLS)

DHCP (Dynamic Host Configuration Protocol)

- Ports 67 (server) and 68 (client), UDP
- Auto-assigns IP address, subnet mask, gateway, DNS server

TFTP (Trivial File Transfer Protocol)

- Port 69, UDP
- Simple transfer of small files (boot files, router/switch configs)
- Insecure: no authentication; controlled environments only

HTTP (Hypertext Transfer Protocol)

- Port 80, TCP
- Web traffic (HTML); stateless
- Unencrypted; secure version is HTTPS (443)
- SSL stripping attack downgrades HTTPS to HTTP

NTP (Network Time Protocol)

- Port 123, UDP
- Synchronizes clocks across the network
- Secure extension: NTS (Network Time Security) adds encryption and authentication

SNMP (Simple Network Management Protocol)

- Ports 161 (commands to devices) and 162 (traps), UDP
- Traps = unsolicited event notifications from devices
- Manages and monitors network devices
- Use v3 (encrypted); v1/v2 send cleartext
- v2c uses plaintext community strings

LDAP (Lightweight Directory Access Protocol)

- Port 389, TCP/UDP
- Accesses directory services (e.g. Microsoft Active Directory)
- Secure version: LDAPS on 636

HTTPS/TLS (HTTPS using Transport Layer Security)

- Port 443
- Secure web browsing; encrypts browser-to-website traffic
- TLS replaces the older SSL

SMB (Server Message Block)

- Port 445, TCP
- Windows file sharing, printing, inter-process communication

Syslog

- Port 514, typically UDP (can use TCP or SSL/TLS)
- Devices send event/log messages to a Syslog server
- Used for monitoring, troubleshooting, security auditing

SMTP TLS / SMTPS (Simple Mail Transfer Protocol over Transport Layer Security)

- Port 587, TCP
- Secure email submission from client to server
- Encrypts SMTP against eavesdropping

LDAPS (Lightweight Directory Access Protocol over SSL)

- Port 636, TCP
- LDAP encrypted with SSL
- Secure directory queries and changes

SQL Server (Structured Query Language Server)

- Port 1433, TCP
- Client connections to Microsoft SQL Server databases

RDP (Remote Desktop Protocol)

- Port 3389, TCP
- Microsoft remote access with a graphical interface (GUI)
- Encrypted

SIP (Session Initiation Protocol)

- Ports 5060 (unsecured) and 5061 (secured with TLS)
- TCP and UDP
- Signaling to start, maintain, and end voice/video sessions
- Core protocol for VoIP

TCP and UDP Port Ranges

- Well-known: 0 - 1023
- Registered: 1024 - 49151
- Dynamic/private: 49152 - 65535