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FTP data transfer port for File Transfer Protocol data connections

OpenSSH listens on TCP 22 by default. Its SFTP subsystem transfers files over SSH, not the historical protocol assigned port 115.

TCP 25 carries SMTP mail transfer, commonly between mail servers. Mail clients should use the submission endpoint specified by their provider.

Simple Mail Transfer Protocol port for mail transmission and routing services

Time Protocol service port for network time synchronization and time queries

Conventional DNS uses port 53 over UDP and TCP. Treating DNS as a UDP-only service can cause incomplete or intermittent resolution.

MTP ，mailtransferprotocol

DHCPv4 servers use UDP 67 and clients use UDP 68. This is an address-lease protocol, not a website to open in a browser.

DHCP client port for Dynamic Host Configuration Protocol

An HTTP URL without an explicit port normally uses 80. The actual web-server configuration determines whether and where a listener exists.

Kerberos authentication protocol port

Post Office Protocol version 2 (POP2)

POP3 (Post Office Protocol 3) for receiving email

Ident - Legacy server identification system, still used by IRC servers for user authentication

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

NTP (Network Time Protocol) port for time synchronization

Microsoft RPCEndpoint Mapper，forWindows RPCService

IMAP on TCP 143 can upgrade a connection with STARTTLS when supported. It differs from implicit TLS on port 993.

BFTP, BackgroundFileTransferProgram

Simple GatewayMonitoringProtocol（[Simple Gateway Monitoring Protocol]( )，SGMP）

SQLservice

Distributed Mail System Protocol port for mail routing and transmission

SNMP (Simple Network Management Protocol) port