RLOGIND(8) | System Manager's Manual | RLOGIND(8) |
rlogind
— remote
login server
rlogind |
[-alnL ] |
rlogind
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
:
-a
-l
-n
-L
auth.info
messages.rlogind
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:
-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,
‘
’; 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.TERM
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.
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.
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.
The rlogind
command appeared in
4.2BSD.
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.
July 17, 2004 | NetBSD 10.99 |