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NetBSD 6.1.5 - man page for rlogind (netbsd section 8)

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RLOGIND(8)			   BSD System Manager's Manual			       RLOGIND(8)

NAME
     rlogind -- remote login server

SYNOPSIS
     rlogind [-alnL]

DESCRIPTION
     rlogind is the server for the rlogin(1) program.  The server provides a remote login facil-
     ity with authentication based on privileged port numbers from trusted hosts.

     Options supported by rlogind:

     -a      Ask hostname for verification.

     -l      Prevent any authentication based on the user's ``.rhosts'' file, unless the user is
	     logging in as the superuser.

     -n      Disable keep-alive messages.

     -L      Log all successful accesses to syslogd(8) as auth.info messages.

     rlogind listens for service requests at the port indicated in the ``login'' service specifi-
     cation; see services(5).  When a service request is received the following protocol is ini-
     tiated:

     1.   The server checks the client's source port.  If the port is not in the range 512-1023,
	  the server aborts the connection.

     2.   The server checks the client's source address and requests the corresponding host name
	  (see getnameinfo(3), hosts(5) and named(8)).	If the hostname cannot be determined, the
	  dot-notation representation of the host address is used.  If the hostname is in the
	  same domain as the server (according to the last two components of the domain name), or
	  if the -a option is given, the addresses for the hostname are requested, verifying that
	  the name and address correspond.  Normal authentication is bypassed if the address ver-
	  ification fails.

     Once the source port and address have been checked, rlogind proceeds with the authentication
     process described in rshd(8).  It then allocates a pseudo terminal (see pty(4)), and manipu-
     lates file descriptors so that the slave half of the pseudo terminal becomes the stdin,
     stdout, and stderr for a login process.  The login process is an instance of the login(1)
     program, invoked with the -f option if authentication has succeeded.  If automatic authenti-
     cation fails, the user is prompted to log in as if on a standard terminal line.

     The parent of the login process manipulates the master side of the pseudo terminal, operat-
     ing as an intermediary between the login process and the client instance of the rlogin(1)
     program.  In normal operation, the packet protocol described in pty(4) is invoked to provide
     '^S/^Q' type facilities and propagate interrupt signals to the remote programs.  The login
     process propagates the client terminal's baud rate and terminal type, as found in the envi-
     ronment variable, 'TERM'; see environ(7).	The screen or window size of the terminal is
     requested from the client, and window size changes from the client are propagated to the
     pseudo terminal.

     Transport-level keepalive messages are enabled unless the -n option is present.  The use of
     keepalive messages allows sessions to be timed out if the client crashes or becomes unreach-
     able.

     At the end of a login session, rlogind invokes the ttyaction(3) facility with an action of
     "rlogind" and user "root" to execute site-specific commands.

DIAGNOSTICS
     All initial diagnostic messages are indicated by a leading byte with a value of 1, after
     which any network connections are closed.	If there are no errors before login(1) is
     invoked, a null byte is returned as in indication of success.

     Try again.
	     A fork(2) by the server failed.

SEE ALSO
     login(1), ruserok(3), ttyaction(3), rshd(8)

HISTORY
     The rlogind command appeared in 4.2BSD.

BUGS
     The authentication procedure used here assumes the integrity of each client machine and the
     connecting medium.  This is insecure, but is useful in an ``open'' environment.

     A facility to allow all data exchanges to be encrypted should be present.

     A more extensible protocol should be used.

     rlogind intentionally rejects accesses from IPv4 mapped address on top of AF_INET6 socket,
     since IPv4 mapped address complicates host-address based authentication.  If you would like
     to accept connections from IPv4 peers, you will need to run rlogind on top of AF_INET
     socket, not AF_INET6 socket.

BSD					  July 17, 2004 				      BSD
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