BINDRESVPORT(3) Linux Programmer s Manual BINDRESVPORT(3)

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 allo- cated.

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.

CONFORMING TO Not in POSIX.1-2001. Present on the BSDs, Solaris, and many other sys- tems.

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 3.22 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at

2008-12-03 BINDRESVPORT(3)