CURLOPT\_PROXY\_TRANSFER\_MODE(3) Library Functions Manual CURLOPT\_PROXY\_TRANSFER\_MODE(3)

# [NAME](#NAME)

CURLOPT\_PROXY\_TRANSFER\_MODE - append FTP transfer mode to URL for proxy

# [SYNOPSIS](#SYNOPSIS)

```
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXY_TRANSFER_MODE,


                          long enabled);
```

# [DESCRIPTION](#DESCRIPTION)

Pass a long. If the value is set to 1 (one), it tells libcurl to set the transfer mode (binary or ASCII) for FTP transfers done via an HTTP proxy, by appending ;type=a or ;type=i to the URL. Without this setting, or it being set to 0 (zero, the default), [*CURLOPT\_TRANSFERTEXT(3)*](/man/os/curl/CURLOPT_TRANSFERTEXT.3) has no effect when doing FTP via a proxy. Beware that not all proxies support this feature.

# [DEFAULT](#DEFAULT)

0, disabled

# [PROTOCOLS](#PROTOCOLS)

This functionality affects all supported protocols

# [EXAMPLE](#EXAMPLE)

```
int main(void)
{


  CURL *curl = curl_easy_init();


  if(curl) {


    CURLcode result;


    curl_easy_setopt(curl, CURLOPT_URL,


                     "ftp://example.com/old-server/file.txt");


    curl_easy_setopt(curl, CURLOPT_PROXY, "http://localhost:80");


    curl_easy_setopt(curl, CURLOPT_PROXY_TRANSFER_MODE, 1L);


    curl_easy_setopt(curl, CURLOPT_TRANSFERTEXT, 1L);


    result = curl_easy_perform(curl);


    curl_easy_cleanup(curl);


  }
}
```

# [AVAILABILITY](#AVAILABILITY)

Added in curl 7.18.0

# [RETURN VALUE](#RETURN_VALUE)

[*curl\_easy\_setopt(3)*](/man/os/curl/curl_easy_setopt.3) returns a CURLcode indicating success or error.

CURLE\_OK (0) means everything was OK, non-zero means an error occurred, see [*libcurl-errors(3)*](/man/os/curl/libcurl-errors.3).

# [SEE ALSO](#SEE_ALSO)

[**CURLOPT\_CRLF**(3)](/man/os/curl/CURLOPT_CRLF.3), [**CURLOPT\_HTTPPROXYTUNNEL**(3)](/man/os/curl/CURLOPT_HTTPPROXYTUNNEL.3), [**CURLOPT\_PROXY**(3)](/man/os/curl/CURLOPT_PROXY.3), [**CURLOPT\_TRANSFERTEXT**(3)](/man/os/curl/CURLOPT_TRANSFERTEXT.3)

2026-10-14 libcurl

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Document: CURLOPT_PROXY_TRANSFER_MODE(3) from curl 8.23.0-r0 (Chainguard OS)
Source: https://github.com/curl/curl.git