A number from 0 through 1023 used to identify a network service on a private IP network or the public Internet. Residing in a field in the TCP or UDP header, the port number directs packets to the appropriate application in the server. The most common well-known ports are 80 and 443, which identify HTTP traffic for a Web server (see
port 80). For details about port numbers, see
TCP/IP port.
Registered and Private Ports
The Internet Assigned Numbers Authority (IANA) registers ports 1024 to 49151 for the convenience of the Internet community. Port numbers from 49152 to 65535 are private ports, also called "dynamic ports." For the complete list of well-known and registered port numbers, visit the iana.org website. See
port scanning,
ICANN and
IANA.
COMMON WELL-KNOWN PORTS
Service Port Function
HTTP 80 Web
HTTPS 443 Web (secure)
FTP 20,21 File transfer
SFTP 22 File transfer (secure)
FTPS 989,990 File transfer (secure)
SIP 5060 VoIP (Internet phone)
DNS 53 Find IP address
SMTP 25 Internet mail
POP3 110 POP mailbox
IMAP 143 IMAP mailbox
Telnet 23 Remote login
SSH 22 Remote login (secure)
NNTP 119 Usenet newsgroups
NNTPS 563 Usenet (secure)
IRC 194 Chat
NTP 123 Network time of day
SNMP 161,162 Network management
CMIP 163,164 Network management
Syslog 514 Event logging
Kerberos 88 Authentication
NetBIOS 137-139 DOS/Windows naming