1---
2c: Copyright (C) Daniel Stenberg, <daniel.se>, et al.
3SPDX-License-Identifier: curl
4Title: CURLOPT_FTPPORT
5Section: 3
6Source: libcurl
7See-also:
8  - CURLOPT_FTP_USE_EPRT (3)
9  - CURLOPT_FTP_USE_EPSV (3)
10---
11
12# NAME
13
14CURLOPT_FTPPORT - make FTP transfer active
15
16# SYNOPSIS
17
18~~~c
19#include <curl/curl.h>
20
21CURLcode curl_easy_setopt(CURL *handle, CURLOPT_FTPPORT, char *spec);
22~~~
23
24# DESCRIPTION
25
26Pass a pointer to a null-terminated string as parameter. It specifies that the
27FTP transfer should be made actively and the given string is used to get the
28IP address to use for the FTP PORT instruction.
29
30The PORT instruction tells the remote server to do a TCP connect to our
31specified IP address. The string may be a plain IP address, a hostname, a
32network interface name (under Unix) or just a '-' symbol to let the library
33use your system's default IP address. Default FTP operations are passive, and
34does not use the PORT command.
35
36The address can be followed by a ':' to specify a port, optionally followed by
37a '-' to specify a port range. If the port specified is 0, the operating
38system picks a free port. If a range is provided and all ports in the range
39are not available, libcurl reports CURLE_FTP_PORT_FAILED for the
40handle. Invalid port/range settings are ignored. IPv6 addresses followed by a
41port or port range have to be in brackets. IPv6 addresses without port/range
42specifier can be in brackets.
43
44Examples with specified ports:
45
46~~~c
47  eth0:0
48  192.168.1.2:32000-33000
49  curl.se:32123
50  [::1]:1234-4567
51~~~
52
53We strongly advise against specifying the address with a name, as it causes
54libcurl to do a blocking name resolve call to retrieve the IP address. That
55name resolve operation does **not** use DNS-over-HTTPS even if
56CURLOPT_DOH_URL(3) is set.
57
58Using anything else than "-" for this option should typically only be done if
59you have special knowledge and confirmation that it works.
60
61You disable PORT again and go back to using the passive version by setting
62this option to NULL.
63
64The application does not have to keep the string around after setting this
65option.
66
67# DEFAULT
68
69NULL
70
71# PROTOCOLS
72
73FTP
74
75# EXAMPLE
76
77~~~c
78int main(void)
79{
80  CURL *curl = curl_easy_init();
81  if(curl) {
82    CURLcode res;
83    curl_easy_setopt(curl, CURLOPT_URL,
84                     "ftp://example.com/old-server/file.txt");
85    curl_easy_setopt(curl, CURLOPT_FTPPORT, "-");
86    res = curl_easy_perform(curl);
87    curl_easy_cleanup(curl);
88  }
89}
90~~~
91
92# AVAILABILITY
93
94Port range support was added in 7.19.5
95
96# RETURN VALUE
97
98Returns CURLE_OK if the option is supported, CURLE_UNKNOWN_OPTION if not, or
99CURLE_OUT_OF_MEMORY if there was insufficient heap space.
100