---
name: "CURLOPT_PROXY_TRANSFER_MODE"
section: "3"
platform: "linux"
package: "curl"
version: "8.23.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux", "macos"]
url: "https://new.carta.tech/CURLOPT_PROXY_TRANSFER_MODE"
---

# CURLOPT\_PROXY\_TRANSFER\_MODE(3)

append FTP transfer mode to URL for proxy

## NAME

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

## SYNOPSIS

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

## 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)](/CURLOPT_TRANSFERTEXT/3.md)* has no effect when doing FTP via a proxy. Beware that not all proxies support this feature.

## DEFAULT

0, disabled

## PROTOCOLS

This functionality affects all supported protocols

## 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

Added in curl 7.18.0

## RETURN VALUE

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

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

## SEE ALSO

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