BSD Rlogin (RFC1258)
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2000-Sep-12
Internet Society Requests For Comment (RFCs)
Status of this Memo
Network Working Group B. Kantor
Request for Comments: 1258 Univ. of Calif San Diego
Status of this Memo
This memo documents an existing protocol and common implementation
that is extensively used on the Internet. This memo provides
information for the Internet community. It does not specify an
Internet standard. Distribution of this memo is unlimited.
The rlogin facility provides a remote-echoed, locally flow-controlled
virtual terminal with proper flushing of output. It is widely used
between Unix hosts because it provides transport of more of the Unix
terminal environment semantics than does the Telnet protocol, and
because on many Unix hosts it can be configured not to require user
entry of passwords when connections originate from trusted hosts.
The rlogin protocol requires the use of the TCP. The contact port is
513. An eight-bit transparent stream is assumed.
Upon connection establishment, the client sends four null-terminated
strings to the server. The first is an empty string (i.e., it
consists solely of a single zero byte), followed by three non-null
strings: the client username, the server username, and the terminal
type and speed. More explicitly:
The server returns a zero byte to indicate that it has received these
strings and is now in data transfer mode. Window size negotiation
may follow this initial exchange (see below).
From Client to Server (and Flow Control)
Initially, the client begins operation in "cooked" (as opposed to
to "raw") mode. In this mode, the START and STOP (usually ASCII
DC1,DC3) characters are intercepted and interpreted by the client to
start and stop output from the remote server to the local terminal,
whereas all other characters are transmitted to the remote host as
they are received. (But see below for the handling of the
In "raw" mode, the START and STOP characters are not processed
locally, but are sent as any other character to the remote server.
The server thus determines the semantics of the START and STOP
characters when in "raw" mode; they may be used for flow control or
have quite different meanings independent of their ordinary usage on
The remote server indicates to the client that it can accept window
size change information by requesting a window size message (as
described below) just after connection establishment and user
identification exchange. The client should reply to this request
with the current window size.
If the remote server h...