
B-1
TCP and UDP Ports and Services BTable B-1 lists common port numbers—well-known ports—assigned to TCP and UDP 
services—well-known services—by the Internet Assigned Networ k Numbers 
Authority (IANA). A more complete list is available in RFC 1700, “Assigned Numbers.” 
Note – If you are configuring a filter on a PortMaster from the command line interface, 
you must use the port number. The PortMaster does not have the /etc/services file and 
cannot use NIS to get the equivalent information.  
Table  B-1 TCP and UDP Port Services
Service Port Protocol Description
ftp-data 20 TCP File Transfer Protocol (FTP) (default data)
ftp 21 TCP FTP (control)
telnet 23 TCP Telnet
smtp  25 TCP  Simple Mail Transfer Protocol (SMTP) 
(email)
nicname 43 TCP  whois Internet directory  service
nicname 43 UDP  whois Internet directory  service
domain  53 TCP  Domain Name System (DNS)
domain 53 UDP DNS
tftp  69 UDP  Trivial File Transfer Protocol (TFTP)
gopher 70 TCP Gopher
gopher 70 UDP Gopher
finger 79 TCP Finger Protocol
finger 79 UDP Finger Protocol
www-http  80 TCP  World Wide Web Hypertext Transfer 
Protocol (HTTP)
https 443 TCP HTTP with SSL (secure HTTP)
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