xref: /aosp_15_r20/external/curl/docs/libcurl/opts/CURLOPT_FTPPORT.md (revision 6236dae45794135f37c4eb022389c904c8b0090d)

---
c: Copyright (C) Daniel Stenberg, <[email protected]>, et al.
SPDX-License-Identifier: curl
Title: CURLOPT_FTPPORT
Section: 3
Source: libcurl
Protocol:
  - FTP
See-also:
  - CURLOPT_FTP_USE_EPRT (3)
  - CURLOPT_FTP_USE_EPSV (3)
Added-in: 7.1
---

# NAME

CURLOPT_FTPPORT - make FTP transfer active

# SYNOPSIS

~~~c
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_FTPPORT, char *spec);
~~~

# 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 hostname, 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:

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

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 **not** use DNS-over-HTTPS even if
CURLOPT_DOH_URL(3) is set.

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

The application does not have to keep the string around after setting this
option.

Using this option multiple times makes the last set string override the
previous ones. You disable PORT again and go back to using the passive version
by setting this option to NULL.

# DEFAULT

NULL

# %PROTOCOLS%

# EXAMPLE

~~~c
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);
  }
}
~~~

# %AVAILABILITY%

# 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.