knownports / Ports 0–99 / Port 21

Port21

  • ftpFile Transfer Protocol [Control]

IANA has registered port 21 to ftp on TCP, UDP and SCTP. It is one of the 88 numbers with an SCTP entry. The entry cites RFC 959. Its TLS counterpart, ftps, is registered on port 990.

  1. 18msp
  2. 19chargen
  3. 20ftp-data
  4. 21ftp
  5. 22ssh
  6. 23telnet
  7. 1 free
  8. 25smtp
TCP assignedUDP assignedSCTP assignedreservedno entryAll 70 assigned numbers in ports 0–99

Registry entries

ServiceProtocolsRegisteredModifiedRFCsOther specs
ftpTCPUDPSCTP—Feb 7, 2022RFC 959, RFC 9260—

Cited RFCs

RFCTitlePublishedStatusLater changes
RFC 959File Transfer ProtocolOctober 1985Internet Standardupdated by RFC 2228, RFC 2640, RFC 2773, RFC 3659, RFC 5797 and 1 more
RFC 9260Stream Control Transmission ProtocolJune 2022Proposed Standard—

Other names built on ftp

574 ftp-agent 989 ftps-data 3305 odette-ftp 6619 odette-ftps

Listed in Ports that cite an RFC · Plain and TLS port pairs · SCTP and DCCP port numbers