bindresvport - bind a socket to a privileged IP port
int bindresvport(int sockfd, struct sockaddr_in *sin);
() is used to bind the socket referred to by the file
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
is not NULL, then sin->sin_port
returns the port number
can be NULL, in which case sin->sin_family
taken to be AF_INET
. However, in this case, bindresvport
no way to return the port number actually allocated. (This information can
later be obtained using getsockname(2)
() returns 0 on success; otherwise -1 is returned and
set to indicate the cause of the error.
() can fail for any of the same reasons as bind(2)
addition, the following errors may occur:
- 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
- sin is not NULL and sin->sin_family is not
For an explanation of the terms used in this section, see attributes(7)
||glibc >= 2.17: MT-Safe . glibc < 2.17: MT-Unsafe
() function uses a static variable that was not protected
by a lock before glibc 2.17, rendering the function MT-Unsafe.
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
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