rlogind(8)rlogind(8)NAMErlogind - The remote login server
SYNOPSISrlogind [-alnxK]
OPTIONS
Requests the addresses for the hostname, verifying that the name and
address correspond. Normal authentication is bypassed if the address
verification fails. Prevents authentication based on the user's
$HOME/.rhosts file, unless the user is logging in as the superuser.
Disables transport-level, keep-alive messages. The messages are enabled
by default. Encrypts the data transmitted between the local host and
the remote host. This option requires that the local and remote hosts
be configured to use Kerberos authentication in the same or trusting
Kerberos realms.
If the rlogind daemon is started with the -x option, only con‐
nections initiated with the -x option from a remote host will be
accepted. All communications between the two hosts will be
encrypted. Specifies that only Kerberos authenticated connec‐
tions will be accepted. This option requires that the local and
remote hosts be configured to use Kerberos authentication in the
same or trusting Kerberos realms.
If the rlogind daemon is started with the -K option, only con‐
nections initiated from a host in the same or trusting Kerberos
domain will be accepted. All communications between the two
hosts will be encrypted.
DESCRIPTION
The rlogind daemon is the server for the rlogin(1) program. The server
provides a remote login facility with authentication based on privi‐
leged port numbers from trusted hosts.
The rlogind daemon listens for service requests at the port indicated
in the login service specification; see services(4). When a service
request is received, the following protocol is initiated: The server
checks the client's source port. If the port is not in the range 512 to
1023, the server aborts the connection. The server checks the client's
source address and requests the corresponding hostname (see gethost‐
byaddr(3), hosts(4) 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 allo‐
cates a pseudoterminal (see pty(7)), and manipulates file descriptors
so that the slave half of the pseudoterminal 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 -l option prevents any
authentication based on the user's file, unless the user is logging in
as the superuser.
By default, the rlogind daemon starts the login dialog using the login
string specified in the message field of the /etc/gettydefs file. If
you want to use a customized banner, create an /etc/issue.net or
/etc/issue file. The rlogind daemon reads the file that exists and
writes its contents to stdout prior to starting the login dialog. If
both files exist, only the /etc/issue.net file is used.
The parent of the login process manipulates the master side of the
pseudoterminal, operating as an intermediary between the login process
and the client instance of the rlogin program. In normal operation,
the packet protocol described in pty(7) is invoked to provide<Ctrl-
s>/<Ctrl-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 TERM environment variable.
The screen or window size of the terminal is requested from the client,
and window size changes from the client are propagated to the pseu‐
doterminal.
Transport-level, keep-alive messages are enabled unless the -n option
is present. The use of keep-alive messages allows sessions to be timed
out if the client crashes or becomes unreachable.
DIAGNOSTICS
All initial diagnostic messages are indicated by a leading byte with a
value of 1 (one), after which any network connections are closed. If
there are no errors before login is invoked, a null byte is returned as
an indication of success. A fork by the server failed. An attempt was
made to start rlogind using the -K flag without first configuring the
system as part of a Kerberos realm.
FILES
Specifies the command path
SEE ALSO
Commands: login(1)
Daemons: rshd(8)
Files: issue(4), issue.net(4)
Functions: ruserok(3)rlogind(8)
