Section (3) bindresvport
bindresvport — bind a socket to a privileged IP port
#include <sys/types.h> #include <netinet/in.h>
|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,
sin is not NULL,
returns the port number actually allocated.
sin can be NULL,
in which case
implicitly taken to be
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
bindresvport() can fail for
any of the same reasons as bind(2). In addition, the
following errors may occur:
The calling process was not privileged (on Linux: the calling process did not have the
CAP_NET_BIND_SERVICEcapability in the user namespace governing its network namespace).
All privileged ports are in use.
- EAFNOSUPPORT (EPFNOSUPPORT in glibc 2.7 and earlier)
sinis not NULL and
For an explanation of the terms used in this section, see attributes(7).
glibc >= 2.17: MT-Safe .\ commit f6da27e53695ad1cc0e2a9490358decbbfdff5e5
glibc < 2.17: MT-Unsafe
uses a static variable that was not protected by a lock
before glibc 2.17, rendering the function MT-Unsafe.
implementations, the glibc implementation ignores any value
that the caller supplies in
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2007-05-31, mtk: Rewrite and substantial additional text.
2008-12-03, mtk: Rewrote some pieces and fixed some errors