Port directory — page 1
Registry assignments, software defaults and local listeners are different things. A port number alone does not identify or secure a service.
Common Ports Overview
FTP data transfer port for File Transfer Protocol data connections
Common Software02
Very Secure FTP Daemon, popular FTP server on Linux
Free FTP server software
OpenSSH listens on TCP 22 by default. Its SFTP subsystem transfers files over SSH, not the historical protocol assigned port 115.
Common Software03
Secure remote login and file transfer protocol
Popular SSH client on Windows platform
SSH secure shell protocol
TCP 25 carries SMTP mail transfer, commonly between mail servers. Mail clients should use the submission endpoint specified by their provider.
Common Software04
MailTransferProxy
MailTransferProxy
SimpleEmailTransportProtocol
Simple Mail Transfer Protocol port for mail transmission and routing services
Common Software02
FileTransferProtocol
FileTransferService
Time Protocol service port for network time synchronization and time queries
Common Software02
TimeProtocolService
RFC 868TimeProtocol
Conventional DNS uses port 53 over UDP and TCP. Treating DNS as a UDP-only service can cause incomplete or intermittent resolution.
Common Software04
Most widely used DNS server software
High-performance DNS server
Kubernetes cluster DNS service port
MTP ，mailtransferprotocol
Common Software02
mailtransferprotocolserver
mailtransfersystem
DHCPv4 servers use UDP 67 and clients use UDP 68. This is an address-lease protocol, not a website to open in a browser.
Common Software03
Internet Systems Consortium DHCP server
Windows built-in DHCP server
DHCPServer
An HTTP URL without an explicit port normally uses 80. The actual web-server configuration determines whether and where a listener exists.
Common Software05
Default port for Apache HTTP server
Default port for Nginx web server
Microsoft's web server integrated in Windows Server
Kerberos authentication protocol port
Common Software02
MIT-developed Kerberos implementation
MicrosoftDirectoryServiceKerberosAuthentication
Post Office Protocol version 2 (POP2)
Common Software02
Post Office Protocol version 2 server
Legacy mail service
POP3 (Post Office Protocol v3) fetches mail over TCP 110. After downloading, whether server copies are deleted depends on the client DELE command and server policy — unlike IMAP (143/993), which is designed to keep copies on the server. POP3 is plaintext; the TLS variant is POP3S on 995.
Common Software04
Ident - Legacy server identification system, still used by IRC servers for user authentication
Common Software02
Identity daemon process
IRC server authentication
IANA assigns TCP 115 to the historical Simple File Transfer Protocol. Its SFTP abbreviation must not be confused with SSH File Transfer Protocol.
Common Software01
IANA assigns TCP 115 to the historical Simple File Transfer Protocol. Its SFTP abbreviation must not be confused with SSH File Transfer Protocol.
SQL service port for database query and management services
Common Software02
OracleSQLNetworkProtocol
databaseservice
NTP (Network Time Protocol) syncs clocks between clients and servers over UDP 123. A wrong system clock breaks TLS certificate validation, scrambles log ordering and invalidates distributed locks.
Common Software03
Microsoft RPCEndpoint Mapper，forWindows RPCService
Common Software03
WindowsRemoteService
Distributed
MicrosoftRemoteService
IMAP on TCP 143 can upgrade a connection with STARTTLS when supported. It differs from implicit TLS on port 993.
Common Software04
BFTP, BackgroundFileTransferProgram
Common Software02
FileTransfer
TransferSystem
Simple GatewayMonitoringProtocol（[Simple Gateway Monitoring Protocol]( )，SGMP）
Common Software02
MonitoringProtocol
NetworkMonitoringTool
Distributed Mail System Protocol port for mail routing and transmission
Common Software02
DistributedMailServiceProtocolServer
MailSystem
SNMP (Simple Network Management Protocol) port
Common Software03
Open-sourceSNMP
WindowsSNMPService
Simple Network Management Protocol for network device monitoring