---
name: "CURLOPT_PROTOCOLS"
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_PROTOCOLS"
---

# CURLOPT\_PROTOCOLS(3)

allowed protocols

## NAME

CURLOPT\_PROTOCOLS - allowed protocols

## SYNOPSIS

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

## DESCRIPTION

This option is deprecated. We strongly recommend using *[CURLOPT\_PROTOCOLS\_STR(3)](/CURLOPT_PROTOCOLS_STR/3.md)* instead because this option cannot control all available protocols.

Pass a long that holds a bitmask of protocol bits. If used, this bitmask limits what protocols libcurl may use in the transfer. This allows you to have a libcurl built to support a wide range of protocols but still limit specific transfers to only be allowed to use a subset of them. By default libcurl accepts all protocols it supports. See also *[CURLOPT\_REDIR\_PROTOCOLS(3)](/CURLOPT_REDIR_PROTOCOLS/3.md)*.

Note that the old define *CURLPROTO\_ALL* no longer enables all protocols a modern curl might support!

These are the available protocol defines:

```
CURLPROTO_DICT
CURLPROTO_FILE
CURLPROTO_FTP
CURLPROTO_FTPS
CURLPROTO_GOPHER
CURLPROTO_HTTP
CURLPROTO_HTTPS
CURLPROTO_IMAP
CURLPROTO_IMAPS
CURLPROTO_LDAP
CURLPROTO_LDAPS
CURLPROTO_MQTT
CURLPROTO_POP3
CURLPROTO_POP3S
CURLPROTO_RTSP
CURLPROTO_SCP
CURLPROTO_SFTP
CURLPROTO_SMTP
CURLPROTO_SMTPS
CURLPROTO_TELNET
CURLPROTO_TFTP
```

## DEFAULT

All protocols built-in.

## PROTOCOLS

This functionality affects all supported protocols

## EXAMPLE

```
int main(int argc, char *argv[])
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode result;
    /* pass in the URL from an external source */
    curl_easy_setopt(curl, CURLOPT_URL, argv[1]);
    /* only allow HTTP, TFTP and SFTP */
    curl_easy_setopt(curl, CURLOPT_PROTOCOLS,
                     CURLPROTO_HTTP | CURLPROTO_TFTP | CURLPROTO_SFTP);
    /* Perform the request */
    result = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}
```

## HISTORY

**CURLPROTO\_**\* macros became *long* types in 8.16.0, prior to this version a *long* cast was necessary when passed to *[curl\_easy\_setopt(3)](/curl_easy_setopt/3.md)*.

## DEPRECATED

Deprecated since 7.85.0.

## AVAILABILITY

Added in curl 7.19.4

## 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\_DEFAULT\_PROTOCOL**(3)](/CURLOPT_DEFAULT_PROTOCOL/3.md), [**CURLOPT\_REDIR\_PROTOCOLS**(3)](/CURLOPT_REDIR_PROTOCOLS/3.md), [**CURLOPT\_URL**(3)](/CURLOPT_URL/3.md)