Top 20 (most commonly open) TCP ports
- Port 22 (SSH) - Secure remote access
- Port 80 (HTTP) - Hypertext Transfer Protocol for web traffic
- Port 443 (HTTPS) - Secure HTTP for encrypted web traffic
- Port 21 (FTP) - File Transfer Protocol for file sharing
- Port 3389 (RDP) - Remote Desktop Protocol for remote administration
- Port 25 (SMTP) - Simple Mail Transfer Protocol for email delivery
- Port 23 (Telnet) - Telnet protocol for remote command-line access
- Port 445 (SMB) - Server Message Block protocol for file sharing
- Port 53 (DNS) - Domain Name System for translating domain names to IP addresses
- Port 110 (POP3) - Post Office Protocol version 3 for email retrieval
- Port 143 (IMAP) - Internet Message Access Protocol for email access
- Port 3306 (MySQL) - MySQL database system
- Port 1723 (PPTP) - Point-to-Point Tunneling Protocol for VPN connections
- Port 1194 (OpenVPN) - OpenVPN protocol for secure VPN connections
- Port 139 (NetBIOS) - NetBIOS session service for communication between computers
- Port 389 (LDAP) - Lightweight Directory Access Protocol for directory services
- Port 465 (SMTPS) - Secure SMTP for encrypted email transmission
- Port 993 (IMAPS) - Secure IMAP for encrypted email access
- Port 1433 (MSSQL) - Microsoft SQL Server database system
- Port 8080 (HTTP Proxy) - Alternate HTTP port often used for proxy servers
Top 20 (most commonly open) UDP ports
- Port 53 (DNS) - Domain Name System for translating domain names to IP addresses
- Port 67 (DHCP) - Dynamic Host Configuration Protocol for automatic IP configuration
- Port 68 (DHCP) - DHCP client port
- Port 123 (NTP) - Network Time Protocol for time synchronization
- Port 161 (SNMP) - Simple Network Management Protocol for network monitoring
- Port 162 (SNMP Trap) - SNMP Trap protocol for sending alerts
- Port 69 (TFTP) - Trivial File Transfer Protocol for basic file transfer
- Port 514 (Syslog) - Syslog protocol for system logging
- Port 1900 (UPnP) - Universal Plug and Play for network device discovery
- Port 500 (IKEv2/IPsec) - Internet Key Exchange version 2 for VPN tunnels
- Port 4500 (NAT-T) - NAT traversal for VPN connections
- Port 1434 (MS-SQL Monitor) - Microsoft SQL Server monitor service
- Port 137 (NetBIOS) - NetBIOS name service for name resolution
- Port 138 (NetBIOS) - NetBIOS datagram service for communication between computers
- Port 161 (SNMP) - Simple Network Management Protocol for network monitoring
- Port 162 (SNMP Trap) - SNMP Trap protocol for sending alerts
- Port 520 (RIP) - Routing Information Protocol for routing table exchange
- Port 111 (RPC) - Remote Procedure Call for inter-process communication
- Port 1900 (SSDP) - Simple Service Discovery Protocol for device discovery
- Port 5353 (mDNS) - Multicast DNS for local domain name resolution