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rexec

BSD mandoc

NAME

rexec - return stream to a remote command

LIBRARY

Lb libcompat

SYNOPSIS

Ft int Fn rexec char **ahost int inport char *user char *passwd char *cmd int *fd2p

DESCRIPTION

Bf -symbolic This interface is obsoleted by rcmd(3). Ef

The Fn rexec function looks up the host Fa *ahost using gethostbyname(3), returning -1 if the host does not exist. Otherwise Fa *ahost is set to the standard name of the host. If a username and password are both specified, then these are used to authenticate to the foreign host; otherwise the environment and then the user's .netrc file in his home directory are searched for appropriate information. If all this fails, the user is prompted for the information.

The port Fa inport specifies which well-known DARPA Internet port to use for the connection; the call Fn getservbyname exec tcp (see getservent(3)) will return a pointer to a structure, which contains the necessary port. The protocol for connection is described in detail in rexecd(8).

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 stdin and stdout If Fa fd2p is non-zero, then an auxiliary channel to a control process will be setup, and a descriptor for it will be placed in Fa *fd2p . The control process will return diagnostic output from the command (unit 2) on this channel, and will also accept bytes on this channel as being UNIX signal numbers, to be forwarded to the process group of the command. The diagnostic information returned does not include remote authorization failure, as the secondary connection is set up after authorization has been verified. If Fa fd2p is 0, then the stderr (unit 2 of the remote command) 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 attention by using out-of-band data.

SEE ALSO

rcmd(3), rexecd(8)

CONFORMING TO

Not in POSIX.1-2001. Present on the BSDs, Solaris, and many other systems. The Fn rexec function appeared in BSD 4.2

BUGS

The Fn rexec function sends the unencrypted password across the network.

The underlying service is considered a big security hole and therefore not enabled on many sites, see rexecd(8) for explanations.