Network Working Group Alex McKenzie Request for Comments: 593 BBN Jon Postel MITRE Telnet and FTP Implementation Schedule Change Telnet and FTP Implementation Schedule Change We have been contacted by several Telnet implementers and concerned users regarding the scheduled changeover from old to new Telnet. There is a good deal of concern about accomplishing a coordinated changeover especially in light of the potential incompatibilities (RFC 559, NIC18482). Therefore the changeover is reformulated as follows. New Telnet implementations are to be ready 1 Jan 74 (as before), but are to use TCP socket 23 (decimal). That is the server Telnet will listen on socket 23, and user Telnet programs will connect to socket 23. It will also be useful for the user program to let the user optionally select the server socket, as many user Telnet programs currently do. It will also be useful for implementers to consider a server Telnet program capable of dealing with both protocols as MIT- DMCG has done (RFC 559). This will provide an opportunity for testing and debugging the new programs in a way that does not interfere with normal use. During January we will survey the technical liaisons to determine the status of the Telnet implementations. As soon as we determine that the Telnet implementations have reached a point where the changeover can be made without disruption of user services the technical liaisons will be notified. In light of this change in the Telnet implementation schedule, the FTP schedule is also modified. New FTP implementations are to be ready by 1 Feb 74 (as before), but will continue to use TCP socket 21 (decimal) until we can determine that a changeover is appropriate. References Telnet Protocol NIC 18639 File Transfer Protocol NIC 17759 [This RFC was put into machine readable form for entry ] [into the online RFC archives by Mirsad Todorovac 5/98 ] McKenzie & Postel [Page 1] RFC 593 Telnet & FTP Implementation Schedule Change November 1973 McKenzie & Postel [Page 2]