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rexecd(8) System Manager's Manual rexecd(8) NAME rexecd - The remote execution server SYNOPSIS rexecd DESCRIPTION The rexecd daemon is the server for the rexec(3) routine. The server provides remote execution facilities with authentication based on user- names and passwords. The rexecd daemon listens for service requests at the port indicated in the exec service specification; see services(4). When a service re- quest is received, the following protocol is initiated: The server reads characters from the socket up to a null (`\0') byte. The resul- tant string is interpreted as an ASCII number, base 10. If the number received in step 1 is nonzero, 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 username of at most 16 bytes is retrieved on the initial socket. A null-terminated, unencrypted password of at most 80 bytes 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. The rexecd server 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 for 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. DIAGNOSTICS Except for the last diagnostic message listed, 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). The name is longer than 16 bytes. The password is longer than 80 bytes. The command line passed exceeds the size of the argument list (as configured into the system). No password file entry for the username existed. The wrong password was supplied. The chdir command to the home directory failed. A fork by the server failed. The user's login shell could not be started. This message is returned on the connection associated with stderr and is not preceded by a flag byte. CAUTIONS IndicatingLogin incorrect as opposed to Password incorrect is a secu- rity breach that allows people to probe a system for users with null passwords. FILES Specifies the command path RELATED INFORMATION Functions: rexec(3) delim off rexecd(8)