Command Section
RLOGIND(8)              FreeBSD System Manager's Manual             RLOGIND(8)

     rlogind - remote login server

     rlogind [-Daln]

     rlogind is deprecated and will be removed from future versions of the
     FreeBSD base system.  If rlogind is still required, it can be installed
     from ports or packages (net/bsdrcmds).

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

     Options supported by rlogind:

     -D      Set TCP_NODELAY socket option.  This improves responsiveness at
             the expense of some additional network traffic.

     -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.

     The rlogind utility listens for service requests at the port indicated in
     the ``login'' service specification; see services(5).  When a service
     request is received the following protocol is initiated:

     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 gethostbyaddr(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
          verification 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 manipulates 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 authentication 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, operating 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 environment 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

     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 unreachable.


     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.

     login(1), ruserok(3), hosts(5), hosts.equiv(5), login.conf(5),
     nologin(5), services(5), rshd(8)

     The rlogind utility appeared in 4.2BSD.

     IPv6 support was added by WIDE/KAME project.

     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.

FreeBSD 11.1-RELEASE-p4          July 3, 2017          FreeBSD 11.1-RELEASE-p4
Command Section