The rexec and rexecd programs allow remote execution. Unlike rlogin, rsh, and rcp, rexecd does not use the trusted host mechanism. A client transmits a message specifying the username, the password, and the name of a command to execute. The rexecd program is susceptible to abuse, because it can be used to probe a system for the names of valid accounts. In addition, passwords are transmitted unencrypted over the network.