.\" **************************************************************************
.\" *                                  _   _ ____  _
.\" *  Project                     ___| | | |  _ \| |
.\" *                             / __| | | | |_) | |
.\" *                            | (__| |_| |  _ <| |___
.\" *                             \___|\___/|_| \_\_____|
.\" *
.\" * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
.\" *
.\" * This software is licensed as described in the file COPYING, which
.\" * you should have received as part of this distribution. The terms
.\" * are also available at https://curl.se/docs/copyright.html.
.\" *
.\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell
.\" * copies of the Software, and permit persons to whom the Software is
.\" * furnished to do so, under the terms of the COPYING file.
.\" *
.\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
.\" * KIND, either express or implied.
.\" *
.\" * SPDX-License-Identifier: curl
.\" *
.\" **************************************************************************
.\"
.TH CURLOPT_FTPPORT 3 "17 Jun 2014" libcurl libcurl
.SH NAME
CURLOPT_FTPPORT \- make FTP transfer active
.SH SYNOPSIS
.nf
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_FTPPORT, char *spec);
.fi
.SH DESCRIPTION
Pass a pointer to a null-terminated string as parameter. It specifies that the
FTP transfer should be made actively and the given string is used to get the
IP address to use for the FTP PORT instruction.

The PORT instruction tells the remote server to do a TCP connect to our
specified IP address. The string may be a plain IP address, a host name, a
network interface name (under Unix) or just a '-' symbol to let the library
use your system's default IP address. Default FTP operations are passive, and
does not use the PORT command.

The address can be followed by a ':' to specify a port, optionally followed by
a '-' to specify a port range. If the port specified is 0, the operating
system picks a free port. If a range is provided and all ports in the range
are not available, libcurl reports CURLE_FTP_PORT_FAILED for the
handle. Invalid port/range settings are ignored. IPv6 addresses followed by a
port or port range have to be in brackets. IPv6 addresses without port/range
specifier can be in brackets.

Examples with specified ports:

.nf
  eth0:0
  192.168.1.2:32000-33000
  curl.se:32123
  [::1]:1234-4567
.fi

We strongly advise against specifying the address with a name, as it causes
libcurl to do a blocking name resolve call to retrieve the IP address. That
name resolve operation does \fBnot\fP use DNS-over-HTTPS even if
\fICURLOPT_DOH_URL(3)\fP is set.

Using anything else than "-" for this option should typically only be done if
you have special knowledge and confirmation that it works.

You disable PORT again and go back to using the passive version by setting
this option to NULL.

The application does not have to keep the string around after setting this
option.
.SH DEFAULT
NULL
.SH PROTOCOLS
FTP
.SH EXAMPLE
.nf
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    curl_easy_setopt(curl, CURLOPT_URL,
                     "ftp://example.com/old-server/file.txt");
    curl_easy_setopt(curl, CURLOPT_FTPPORT, "-");
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}
.fi
.SH AVAILABILITY
Port range support was added in 7.19.5
.SH RETURN VALUE
Returns CURLE_OK if the option is supported, CURLE_UNKNOWN_OPTION if not, or
CURLE_OUT_OF_MEMORY if there was insufficient heap space.
.SH "SEE ALSO"
.BR CURLOPT_FTP_USE_EPRT (3),
.BR CURLOPT_FTP_USE_EPSV (3)