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Ports

Introduction

  • Port number is a 16-bit numerical value that ranges from 0 to 65535. Well-known port (0-1023), registered port (1024-49151), and dynamic port is three types of port number space. (49152-65535).

  • These ports can be opened and used by software applications and operating system services to send and receive data over networks (LAN or WAN) that employ certain protocols (eg TCP, UDP).

  • To conclude, a port is a logical form to identify system activities or various network services used to create local or network-based communications.

  • For example, we use 80 for HTTP-web-based plain-text surfing and 443 for HTTPS-web-based encrypted websites in our daily work.

What are the functions of ports?

  • When interacting over the Internet, TCP and UDP protocols make connections, recompile data packages after the transfer, and then deliver them to applications on the recipient’s device.

  • For this handover to work, the operating system must install and open the gateway for the transfer.

  • Each door has a unique code number. After transmission, the receiving system uses the port number to determine where the data should be sent. The port numbers of the sender and receiver are always included in the data packet.

  • Ports are assigned sequential numbers from 0 to 65535. Some of these codes are standardized, meaning they are assigned to certain uses. Since code numbers are universally recognized and permanently assigned, these standard ports are also known as well-known ports.

  • Registered ports are those that organizations or software developers have registered for their applications. Registration is handled by the Internet Assigned Numbers Authority (IANA). A diverse selection of dynamically assigned port numbers is also available. For example, when viewing websites, browsers use these ports. After that, the phone number is free again.

Why is it important to know these ports?

  • Any security researcher, bug bounty hunter, or anyone working with service configuration would benefit from this.

  • Knowing how to do more thorough scans such as version detection or known vulnerabilities for ancient services that are still operating in the infrastructure, especially when using tools like Nmap, is handy when getting to know these protocols and services.

The most 50 significant ports are listed here:

The following are some of the most common service names, transport protocol names, and port numbers used to differentiate between specific services that employ TCP, UDP, DCCP, and SCTP.

Port Number Service Name Protocol Name/ Transport protocol Desctriptin
7 Echo TCP, UDP Echo Service
20 FTP-data TCP, SCTP File Transfer Protocol data transfer
21 FTP TCP, UDP, SCTP File Transfer Protocol (FTP) control connection
22 SSH-SCP TCP, UDP, SCTP Secure Shell, secure logins, file transfers (scp, sftp), and port forwarding
23 Telnet TCP Telnet protocol—unencrypted text communications
25 SMTP TCP Simple Mail Transfer Protocol, used for email routing between mail servers
53 DNS TCP, UDP Domain Name System name resolver
69 TFTP UDP Trivial File Transfer Protocol
80 HTTP TCP, UDP, SCTP Hypertext Transfer Protocol (HTTP) uses TCP in versions 1.x and 2. HTTP/3 uses QUIC, a transport protocol on top of UDP
88 Kerberos TCP, UDP Network Authentication System,
102 Iso-trap TCP ISO Transport Service Access Point (TSAP) Class 0 protocol
110 POP3 TCP Post Office Protocol, version 3 (POP3)
135 Microsoft EMAP TCP,UDP Microsoft EPMAP (End Point Mapper), also known as DCE/RPC Locator service, used to remotely manage services including DHCP server, DNS server, and WINS. Also used by DCOM
137 NetBIOS-ns TCP, UDP NetBIOS Name Service, used for name registration and resolution
139 NetBIOS-ssn TCP, UDP NetBIOS Session Service
143 IMAP4 TCP, UDP Internet Message Access Protocol (IMAP), management of electronic mail messages on a server
381 HP Openview TCP, UDP HP data alarm manager
388 HP Openview TCP, UDP HP data performance collector
443 HTTP over SSL TCP, UDP, SCTP Hypertext Transfer Protocol Secure (HTTPS) uses TCP in versions 1.x and 2. HTTP/3 uses QUIC, a transport protocol on top of UDP.
464 Kerberos TCP, UDP Kerberos Change/Set password
465 SMTP over TLS/SSL, SSM TCP Authenticated SMTP over TLS/SSL (SMTPS), URL Rendezvous Directory for SSM (Cisco protocol)
587 SMTP TCP Email message submission
593 Microsoft DCOM TCP, UDP HTTP RPC Ep Map, Remote procedure call over Hypertext Transfer Protocol, often used by Distributed Component Object Model services and Microsoft Exchange Server
636 LDAP over TLS/SSL TCP, UDP Lightweight Directory Access Protocol over TLS/SSL
691 MS Exchange TCP MS Exchange Routing
902 VMware Server unofficial VMware ESXi
989 FTP over SSL TCP, UDP FTPS Protocol (data), FTP over TLS/SSL
989 FTP over SSL TCP, UDP FTPS Protocol (data), FTP over TLS/SSL
993 IMAP4 over SSL TCP Internet Message Access Protocol over TLS/SSL (IMAPS)
995 POP3 over SSL TCP, UDP Post Office Protocol 3 over TLS/SSL
1025 Microsoft RPC TCP Microsoft operating systems tend to allocate one or more unsuspected, publicly exposed services (probably DCOM, but who knows) among the first handful of ports immediately above the end of the service port range (1024+).
1194 OpenVPN TCP, UDP OpenVPN
1337 WASTE unofficial WASTE Encrypted File Sharing Program
1589 Cisco VQP TCP, UDP Cisco VLAN Query Protocol (VQP)
1725 Stream UDP Valve Steam Client uses port 1725
2082 cPanel unofficial cPanel default
2083 radsec, cPanel TCP, UDP cPanel default
2483 Oracle DB TCP, UDP Oracle database listening for insecure client connections to the listener, replaces port 1521
2484 Oracle DB TCP, UDP Oracle database listening for SSL client connections to the listener
2967 Symantec AV TCP, UDP Symantec System Center agent (SSC-AGENT)
3074 XBOX Live TCP, UDP Xbox LIVE and Games for Windows – Live
3306 MySQL TCP MySQL database system
3724 World of Warcraft TCP, UDP Blizzard games, Unofficial Club Penguin Disney online game for kids
3389 MS wbt-server TCP Microsoft Remote Desktop Protocol
4664 Google Desktop unofficial Google Desktop Search
5432 Postgres SQL TCP PostgreSQL database system
5900 RFB/VNC Server TCP virtual Network Computing (VNC) Remote Frame Buffer (RFB) protocol
6665-6669 IRC TCP Internet Relat Chat
6881 BitTorrent unofficial BitTorrent is part of the full range of ports used most often
6970 Quicktime unofficial QuickTime Streaming Server
6999 BitTorrent unofficial BitTorrent is part of the full range of ports used most often
8086 Kaspersky AV TCP Kaspersky AV Control Center
8087 Kaspersky UDP Kaspersky AV Control Center
8222 VMware Server TCP, UDP VMware Server Management User Interface (insecure Web interface).
9100 PDL TCP PDL Data Stream, used for printing to certain network printers.
10000 BackupExec unofficial Webmin, Web-based Unix/Linux system administration tool (default port)
12345 NetBus unofficial NetBus remote administration tool (often Trojan horse).
27374 Sub7 unofficial Sub7 default
31337 Back Orifice unofficial Back Orifice 2000 remote administration tools

Miscellaneous