BINDRESVPORT(3) Library Functions Manual BINDRESVPORT(3)

# [NAME](#NAME)

`bindresvport`, `bindresvport_sa` — bind a socket to a privileged IP port

# [SYNOPSIS](#SYNOPSIS)

`#include <sys/types.h>`  
`#include <rpc/rpc.h>`

`int`  
`bindresvport`(`int sd`, `struct sockaddr_in *sin`);

`int`  
`bindresvport_sa`(`int sd`, `struct sockaddr *sa`);

# [DESCRIPTION](#DESCRIPTION)

The [`bindresvport`](#bindresvport)() and [`bindresvport_sa`](#bindresvport_sa)() functions are used to bind a socket descriptor to a privileged IP port, that is, a port number in the range 0-1023.

If `sin` is a pointer to a `struct sockaddr_in` then the appropriate fields in the structure should be defined. Note that `sin->sin_family` must be initialized to the address family of the socket, passed by `sd`. If `sin->sin_port` is ‘0’ then an anonymous port (in the range 600-1023) will be chosen, and if [bind(2)](/man/os/libtirpc-nokrb/bind.2) is successful, the `sin->sin_port` will be updated to contain the allocated port.

If `sin` is the `NULL` pointer, an anonymous port will be allocated (as above). However, there is no way for [`bindresvport`](#bindresvport~2)() to return the allocated port in this case.

Only root can bind to a privileged port; this call will fail for any other users.

Function prototype of [`bindresvport`](#bindresvport~3)() is biased to `AF_INET` socket. The [`bindresvport_sa`](#bindresvport_sa~2)() function acts exactly the same, with more neutral function prototype. Note that both functions behave exactly the same, and both support `AF_INET6` sockets as well as `AF_INET` sockets.

# [RETURN VALUES](#RETURN_VALUES)

The `bindresvport`() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable `errno` is set to indicate the error.

# [ERRORS](#ERRORS)

\[[`EPFNOSUPPORT`](#EPFNOSUPPORT)]

If second argument was supplied, and address family did not match between arguments.

The `bindresvport`() function may also fail and set `errno` for any of the errors specified for the calls [bind(2)](/man/os/libtirpc-nokrb/bind.2), [getsockopt(2)](/man/os/libtirpc-nokrb/getsockopt.2), or [setsockopt(2)](/man/os/libtirpc-nokrb/setsockopt.2).

# [AVAILABILITY](#AVAILABILITY)

The [`bindresvport`](#bindresvport~4)() function is part of libtirpc.

# [SEE ALSO](#SEE_ALSO)

[bind(2)](/man/os/libtirpc-nokrb/bind.2), [getsockopt(2)](/man/os/libtirpc-nokrb/getsockopt.2), [setsockopt(2)](/man/os/libtirpc-nokrb/setsockopt.2)

November 22, 1987 Linux 4.19.0-gvisor

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Document: bindresvport(3t) from libtirpc-nokrb 1.3.8-r0 (Chainguard OS)
Source: https://downloads.sourceforge.net/project/libtirpc/libtirpc/1.3.8/libtirpc-1.3.8.tar.bz2