rexecd

Remote execution daemon

Syntax:

rexecd

Options:

None.

Description:

The rexecd daemon provides remote execution facilities with authentication based on usernames and passwords.

The rexec daemon is started when inetd receives a service request at the port indicated by the exec entry (inetd listens for service requests specified in the inetd.conf file at a port defined in the services file). The following protocol is initiated:

1. The daemon reads characters from the socket up to a NULL (\0) byte. The resultant string is interpreted as an ASCII number, base 10.
2. If the number received in step 1 is nonzero, it's interpreted as the port number of a secondary stream to be used for standard error. A second connection is then created to the specified port on the client's machine.
3. A NULL-terminated username of at most 16 characters is retrieved on the initial socket.
4. A NULL-terminated, unencrypted password of at most 16 characters is retrieved on the initial socket.
5. 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 boundary on the size of the system's argument list.
6. The rexecd daemon validates the user as is done at login time; if the authentication is successful, rexecd 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.
7. 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.

Diagnostics

All diagnostic messages (except "<shellname>: ...") are returned on the initial socket, after which any network connections are closed. A leading byte with a value of 1 indicates an error (0 is returned in step 7 above upon successful completion of the previous steps).

command too long

The command line passed is > the size of the argument list (as configured into the system).

Login incorrect

No password file entry for the username existed.

No remote directory

The chdir command to the home directory failed.

Password incorrect

The wrong password was given.

password too long

The password is > 16 characters.

<shellname>: ...

The user's login shell couldn't be started. This message is returned on the link associated with standard error and isn't preceded by a flag byte.

Try again

A fork by the server failed.

username too long

The name is > 16 characters.

The rexec utility isn't implemented in QNX.

See also:

inetd

/etc/services file

The inetd daemon section in the Basic Configuration chapter