NAME

       bindresvport - bind a socket to a privileged IP port

SYNOPSIS

       #include <sys/types.h>
       #include <netinet/in.h>

       int bindresvport(int sockfd, struct sockaddr_in *sin);

DESCRIPTION

       bindresvport()  is  used  to  bind a socket descriptor to a privileged anonymous IP port, that is, a port
       number arbitrarily selected from the range 512 to 1023.

       If the bind(2) performed by bindresvport() is successful, and sin is not NULL, then sin->sin_port returns
       the port number actually allocated.

       sin can be NULL, in which case sin->sin_family is implicitly taken to be AF_INET.  However, in this case,
       bindresvport() has no way to return the port number actually allocated.  (This information can  later  be
       obtained using getsockname(2).)

RETURN VALUE

       bindresvport()  returns 0 on success; otherwise -1 is returned and errno set to indicate the cause of the
       error.

ERRORS

       bindresvport() can fail for any of the same reasons as bind(2).  In addition, the  following  errors  may
       occur:

       EACCES The caller did not have superuser privilege (to be precise: the CAP_NET_BIND_SERVICE capability is
              required).

       EADDRINUSE
              All privileged ports are in use.

       EAFNOSUPPORT (EPFNOSUPPORT in glibc 2.7 and earlier)
              sin is not NULL and sin->sin_family is not AF_INET.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).
       ┌────────────────┬───────────────┬─────────────────────────┐
       │ Interface      │ Attribute     │ Value                   │
       ├────────────────┼───────────────┼─────────────────────────┤
       │ bindresvport() │ Thread safety │ glibc >= 2.17: MT-Safe  │
       │                │               │ glibc < 2.17: MT-Unsafe │
       └────────────────┴───────────────┴─────────────────────────┘

       The  bindresvport()  function  uses a static variable that was not protected by a lock before glibc 2.17,
       rendering the function MT-Unsafe.

CONFORMING TO

       Not in POSIX.1.  Present on the BSDs, Solaris, and many other systems.

NOTES

       Unlike some bindresvport() implementations, the glibc implementation ignores any value  that  the  caller
       supplies in sin->sin_port.

SEE ALSO

       bind(2), getsockname(2)

COLOPHON

       This  page  is  part  of  release  4.04  of  the  Linux man-pages project.  A description of the project,
       information  about  reporting  bugs,  and  the  latest  version  of  this   page,   can   be   found   at
       http://www.kernel.org/doc/man-pages/.

                                                   2015-03-02                                    BINDRESVPORT(3)