bindresvport - bind a socket to a privileged IP port


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

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


   bindresvport()  is  used  to  bind  the  socket referred to by the file
   descriptor sockfd 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

   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).)


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


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

   EACCES The calling process was not privileged (on  Linux:  the  calling
          process  did not have the CAP_NET_BIND_SERVICE capability in the
          user namespace governing its network namespace).

          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.


   For  an  explanation  of  the  terms  used   in   this   section,   see

   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-


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


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


   bind(2), getsockname(2)


   This page is part of release 4.09 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

                              2016-10-08                   BINDRESVPORT(3)


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