CURLOPT\_PROTOCOLS(3) Library Functions Manual CURLOPT\_PROTOCOLS(3)

# [NAME](#NAME)

CURLOPT\_PROTOCOLS - allowed protocols

# [SYNOPSIS](#SYNOPSIS)

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

# [DESCRIPTION](#DESCRIPTION)

This option is deprecated. We strongly recommend using [*CURLOPT\_PROTOCOLS\_STR(3)*](/man/os/curl/CURLOPT_PROTOCOLS_STR.3) 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)*](/man/os/curl/CURLOPT_REDIR_PROTOCOLS.3).

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](#DEFAULT)

All protocols built-in.

# [PROTOCOLS](#PROTOCOLS)

This functionality affects all supported protocols

# [EXAMPLE](#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](#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)*](/man/os/curl/curl_easy_setopt.3).

# [DEPRECATED](#DEPRECATED)

Deprecated since 7.85.0.

# [AVAILABILITY](#AVAILABILITY)

Added in curl 7.19.4

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

2026-10-19 libcurl

---

Document: CURLOPT_PROTOCOLS(3) from curl 8.23.0-r1 (Chainguard OS)
Source: https://github.com/curl/curl.git