bindresvport(3) - Linux man page
Name
bindresvport - bind a socket to a privileged IP portSynopsis
#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 allocated.
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.