rlogind(8) System Manager's Manual rlogind(8)
NAME
rlogind - The remote login server
SYNOPSIS
rlogind [-aln]
FLAGS
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. Dis-
ables transport-level, keep-alive messages. The messages are enabled by default.
DESCRIPTION
The rlogind daemon is the server for the rlogin(1) program. The server provides a remote login facility with authentication based on priv-
ileged 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
gethostbyaddr(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 flag 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, std-
out, 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 pre-
vents any authentication based on the user's .rhosts 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 pseudoterminal.
Transport-level, keep-alive messages are enabled unless the -n flag is present. The use of keep-alive messages allows sessions to be timed
out if the client crashes or becomes unreachable.
Note that 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.
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.
FILES
Specifies the command path
RELATED INFORMATION
Commands: login(1).
Daemons: rshd(8).
Files: issue(4), issue.net.
Functions: ruserok(3). delim off
rlogind(8)