This security-sensitive command uses the SIA (Security Integration Architecture) routine as an interface to the security mechanisms. See the matrix.conf4 reference page for more information.
The rshd daemon listens for service requests at the port indicated in the cmd 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 reads bytes 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 2 is nonzero, it is interpreted as the port number of a secondary stream to be used for the stderr option. A second connection is then created to the specified port on the client's machine. The source port of this second connection is also in the range 512 to 1023. 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. If address verification fails, the connection is aborted with the message Host address mismatch. A null-terminated username of at most 16 bytes is retrieved on the initial socket. This username is interpreted as the user identity on the client 's machine. A null-terminated username of at most 16 bytes is retrieved on the initial socket. This username is interpreted as a user identity to use on the server's machine. 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. The rshd daemon then validates the user using ruserok(3), which uses the file /etc/hosts.equiv and the .rhosts file found in the user's home directory. The -l flag prevents ruserok(3) from doing any validation based on the user's .rhosts file, unless the user is the superuser. 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 rshd.
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.
Specifies the command path
Functions: rcmd(3), ruserok(3) delim off