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)