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Member "logdaemon-5.14/rexecd/rexecd.8" of archive logdaemon-5.14.tar.gz:
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rexecd - remote execution server
/etc/rexecd
Rexecd is the server for the rexec(3) routine. The server provides
remote execution facilities with authentication based on user names and
passwords.
Rexecd listens for service requests at the port indicated in
the ‘‘exec’’ service specification; see services(5). When a service request
is received the following protocol is initiated:
- The server reads characters
from the socket up to a null (‘\0’) byte. The resultant string is interpreted
as an ASCII number, base 10.
- If the number received in step 1 is non-zero,
it is interpreted as the port number of a secondary stream to be used for
the stderr. A second connection is then created to the specified port on
the client’s machine.
- A null terminated user name of at most 16 characters
is retrieved on the initial socket.
- A null terminated, unencrypted password
of at most 16 characters is retrieved on the initial socket.
- A null terminated
command to be passed to a shell is retrieved on the initial socket. The
length of the command is limited by the upper bound on the size of the
system’s argument list.
- Rexecd then validates the user as is done at login
time and, if the authentication was successful, changes to the user’s home
directory, and establishes the user and group protections of the user. If
any of these steps fail the connection is aborted with a diagnostic message
returned.
- A null byte is returned on the initial socket and the command
line is passed to the normal login shell of the user. The shell inherits
the network connections established by rexecd.
Except for the
last one listed below, all diagnostic messages are returned on the initial
socket, after which any network connections are closed. An error is indicated
by a leading byte with a value of 1 (0 is returned in step 7 above upon
successful completion of all the steps prior to the command execution).
‘‘username too long’’
The name is longer than 16 characters.
‘‘password too long’’
The password is longer than 16 characters.
‘‘command too long ’’
The command line passed exceeds the size of the argument list (as configured
into the system).
‘‘Login incorrect.’’
No password file entry for the user name existed.
‘‘Password incorrect.’’
The wrong was password supplied.
‘‘No remote directory.’’
The chdir command to the home directory failed.
‘‘Try again.’’
A fork by the server failed.
‘‘<shellname>: ...’’
The user’s login shell could not be started. This message is returned on
the connection associated with the stderr, and is not preceded by a flag
byte.
rexec(3)
A facility to allow all data and password exchanges
to be encrypted should be present.
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