Port 20: FTP - Transfers files (insecure)
Port 22: SSH - Secure remote login & file transfer
Port 23: Telnet - Unsecure remote login (rarely used)
Port 25: SMTP - Sends emails (unsecure)
Port 49: TACACS+ - Cisco authentication protocol
Port 53: DNS - Resolves domain names to Ips
Port 67: DHCP - Assigns IP addresses dynamically
Port 69: TFTP - Simple file transfer (no authentication)
Port 80: HTTP - Unencrypted web browsing
Port 110: POP3 - Retrieves emails (unsecure)
Port 143: IMAP - Manages emails on server (unsecure)
Port 161: SNMP - Network monitoring & management
Port 443: HTTPS - Secure web browsing (TLS/SSL)
Port 389: LDAP - Directory services (unsecure)
Port 500: IKE - Internet Key Exchange (IPSec VPN)
Port 587: SMTP w/ STARTTLS - Secure email sending
Port 636: LDAPS - Secure directory services
Port 993: IMAPS - Secure email retrieval (IMAP)
Port 995: POP3S - Secure email retrieval (POP3
Port 1194: OpenVPN - Secure VPN tunnel
Port 1433: MSSQL - Microsoft SQL database
Port 1521: Oracle SQL - Oracle database
Port 1701: L2TP - VPN tunnelling protocol
Port 1723: PPTP - VPN protocol (outdated)
Port 1812: RADIUS - Network authentication service
Port 3306: MySQL - MySQL database
Port 3389: RDP - Remote desktop access for Windows
Port 4500: IPSec NAT-T - IPSec VPN with NAT
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