The error code EAGAIN is overloaded to mean "All network ports in use."įor information on the return from ruserok() and iruserok(), see above. It returns -1 on error with the global value errno set according The rresvport() function returns a valid, bound socket descriptor on success. It returns -1 on error and prints a diagnostic message on the standard error. The rcmd() function returns a valid socket descriptor on success. For these functions, the af argument can be specified as AF_INET or AF_INET6.
The "_af" variants take an extra argument that allows the socket addressįamily to be specified. *_af() variants All of the functions described above work with IPv4 ( AF_INET) sockets. If the IP address of the remote host is known, iruserok() should be used in preference to ruserok(), as it does not require trusting the DNS The remote domain, only the machine name need be specified. If the local domain (as obtained from gethostname(2)) is the same as rhosts file otherwise iruserok() and ruserok() return -1. Zero is returned if the machine name is listed in the hosts.equiv file, or the host and remote username are found in the If this file does not exist, is not a regular file, is owned by anyone other than the user or the superuser, or is writable by anyone other than the owner, rhosts in the local user's home directory is checked to see if the request for service is allowed. If that lookup is notĭone, or is unsuccessful, the. Then, if the user is not the superuser, it checks the /etc/hosts.equiv file. Local user's name is that of the superuser. Iruserok() and ruserok() The iruserok() and ruserok() functions take a remote host's IP address or name, respectively, two usernames and a flag indicating whether the Supplies to the call is used as the starting point for a circular search of the port range on (successful) return, it contains the port number that was bound The port argument is value-result: the value it In the glibc implementation, this function restricts its search to the ports from 512 to 1023. Only a privileged process ( CAP_NET_BIND_SERVICE) is allowed to bind to a privileged Privileged ports are those in the range 0 to 1023. This socket is suitable for use by rcmd() and several Rresvport() The rresvport() function is used to obtain a socket with a privileged port bound to it. The protocol is described in detail in rshd(8). Will be made the same as the stdout and no provision is made for sending arbitrary signals to the remote process, although you may be able to get its If fd2p is 0, then the stderr (unit 2 of the remote command) The control process will return diagnostic output from the command (unit 2) on this channel, and will also accept bytes on this channelĪs being UNIX signal numbers, to be forwarded to the process group of the command. If fd2p is nonzero, then an auxiliary channel to a control process will be set up, and a descriptor for it will be If the connection succeeds, a socket in the Internet domain of type SOCK_STREAM is returned to the caller, and given to the remote command as Is set to the standard name of the host and a connection is established to a server residing at the well-known Internet port inport. Rcmd() The rcmd() function looks up the host *ahost using gethostbyname(3), returning -1 if the host does not exist. All four functions are used by the rshd(8) Ruserok() functions are used by servers to authenticate clients requesting service with rcmd(). The rresvport() function returns a descriptor to a socket with an address in the privileged port space. The rcmd() function is used by the superuser to execute a command on a remote machine using an authentication scheme based on privileged port Rcmd(), rcmd_af(), rresvport(), rresvport_af(), iruserok(), iruserok_af(), ruserok(), ruserok_af(): Int ruserok_af(const char * rhost, int superuser ,įeature Test Macro Requirements for glibc (see feature_test_macros(7)): Int iruserok_af(uint32_t raddr, int superuser ,Ĭonst char * ruser, const char * luser, sa_family_t af ) Int rresvport_af(int * port, sa_family_t af )
Int rcmd_af(char ** ahost, int inport, const char * locuser ,Ĭonst char * remuser, const char * cmd, int * fd2p , Int ruserok(const char * rhost, int superuser , Int iruserok(uint32_t raddr, int superuser ,Ĭonst char * ruser, const char * luser ) Int rcmd(char ** ahost, int inport, const char * locuser ,Ĭonst char * remuser, const char * cmd, int * fd2p ) Synopsis #include /* Or on some systems */ Rcmd, rresvport, iruserok, ruserok, rcmd_af, rresvport_af, iruserok_af, ruserok_af - routines for returning a stream to a remote command
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