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GETPEEREID(3)		    Library Functions Manual		 GETPEEREID(3)

NAME
       getpeereid -- get the effective credentials of a	UNIX-domain peer

LIBRARY
       Standard	C Library (libc, -lc)

SYNOPSIS
       #include	<unistd.h>

       int
       getpeereid(int s, uid_t *euid, gid_t *egid);

DESCRIPTION
       The  getpeereid()  function returns the effective user and group	IDs of
       the peer	connected to a Unix-domain socket.  The	argument s must	 be  a
       connected Unix-domain socket (unix(4)) of type SOCK_STREAM on which ei-
       ther connect(2) or listen(2) has	been called.  The effective user ID is
       placed in euid, and the effective group ID in egid.

       The  credentials	returned to the	listen(2) caller are those of its peer
       at the time it called  connect(2);  the	credentials  returned  to  the
       connect(2)  caller  are	those  of  its	peer  at  the  time  it	called
       listen(2).  This	mechanism is reliable; there is	no way for either side
       to influence the	credentials returned to	its peer except	by calling the
       appropriate system call (i.e., either connect(2)	 or  listen(2))	 under
       different effective credentials.

       One  common  use	 of this routine is for	a Unix-domain server to	verify
       the credentials of its client.  Likewise, the  client  can  verify  the
       credentials of the server.

IMPLEMENTATION NOTES
       On  FreeBSD, getpeereid() is implemented	in terms of the	LOCAL_PEERCRED
       unix(4) socket option.

RETURN VALUES
       The getpeereid()	function returns the value 0 if	successful;  otherwise
       the  value -1 is	returned and the global	variable errno is set to indi-
       cate the	error.

ERRORS
       The getpeereid()	function fails if:

       [EBADF]		  The argument s is not	a valid	descriptor.

       [ENOTSOCK]	  The argument s is a file, not	a socket.

       [ENOTCONN]	  The argument s does not refer	to a socket  on	 which
			  connect(2) or	listen(2) have been called.

       [EINVAL]		  The  argument	 s  does not refer to a	socket of type
			  SOCK_STREAM, or the kernel returned invalid data.

SEE ALSO
       connect(2), getpeername(2), getsockname(2),  getsockopt(2),  listen(2),
       unix(4)

HISTORY
       The getpeereid()	function appeared in FreeBSD 4.6.

FreeBSD	13.4		       November	16, 2023		 GETPEEREID(3)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=getpeereid&sektion=3&manpath=FreeBSD+13.4-RELEASE+and+Ports>

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