bindresvport(3)

1BINDRESVPORT(3)            Linux Programmer's Manual           BINDRESVPORT(3)
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NAME

6       bindresvport - bind a socket to a privileged IP port
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SYNOPSIS

9       #include <sys/types.h>
10       #include <netinet/in.h>
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12       int bindresvport(int sockfd, struct sockaddr_in *sin);
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DESCRIPTION

15       bindresvport()  is  used  to  bind  a socket descriptor to a privileged
16       anonymous IP port, that is, a port number arbitrarily selected from the
17       range 512 to 1023.
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19       If  the  bind(2)  performed by bindresvport() is successful, and sin is
20       not NULL, then sin->sin_port returns the  port  number  actually  allo‐
21       cated.
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23       sin  can  be NULL, in which case sin->sin_family is implicitly taken to
24       be AF_INET.  However, in this case, bindresvport() has no way to return
25       the  port  number  actually  allocated.  (This information can later be
26       obtained using getsockname(2).)
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RETURN VALUE

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

33       bindresvport()  can  fail  for  any of the same reasons as bind(2).  In
34       addition, the following errors may occur:
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36       EACCES The caller did not have superuser privilege (to be precise:  the
37              CAP_NET_BIND_SERVICE capability is required).
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39       EADDRINUSE
40              All privileged ports are in use.
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42       EAFNOSUPPORT (EPFNOSUPPORT in glibc 2.7 and earlier)
43              sin is not NULL and sin->sin_family is not AF_INET.
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ATTRIBUTES

46   Multithreading (see pthreads(7))
47       Before  glibc  2.17, the bindresvport() function uses a static variable
48       that is not protected, so it is not thread-safe.
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50       Since glibc 2.17, the bindresvport() function uses a  lock  to  protect
51       static variable, so it is thread-safe.
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CONFORMING TO

54       Not in POSIX.1-2001.  Present on the BSDs, Solaris, and many other sys‐
55       tems.
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NOTES

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

65       This  page  is  part of release 3.53 of the Linux man-pages project.  A
66       description of the project, and information about reporting  bugs,  can
67       be found at http://www.kernel.org/doc/man-pages/.
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71                                  2013-06-21                   BINDRESVPORT(3)