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CURLOPT_SOCKS5_AUTH(3) Library Functions Manual CURLOPT_SOCKS5_AUTH(3)

NAME

CURLOPT_SOCKS5_AUTH - methods for SOCKS5 proxy authentication

SYNOPSIS

#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SOCKS5_AUTH, long bitmask);

DESCRIPTION

Pass a long as parameter, which is set to a bitmask, to tell libcurl which authentication method(s) are allowed for SOCKS5 proxy authentication. The only supported flags are CURLAUTH_BASIC, which allows username/password authentication, CURLAUTH_GSSAPI, which allows GSS-API authentication, and CURLAUTH_NONE, which allows no authentication. Set the actual username and password with the CURLOPT_PROXYUSERPWD(3) option.

The specific socks authentication method is an access property, it does not change the security context. This means that this option changes how the connection and access to the proxy happens when a connection is setup, but it does not affect which proxy connections libcurl can reuse. libcurl may reuse a connection that was set up with a different socks authentication method. Proxy connection reuse still depends on other properties matching, such as the protocol, proxy hostname, port number, credentials and other settings that affect the connection.

DEFAULT

CURLAUTH_BASIC | CURLAUTH_GSSAPI

PROTOCOLS

This functionality affects all supported protocols

EXAMPLE

int main(void)
{

CURL *curl = curl_easy_init();
if(curl) {
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
/* request to use a SOCKS5 proxy */
curl_easy_setopt(curl, CURLOPT_PROXY, "socks5://user:pass@myproxy.com");
/* enable username/password authentication only */
curl_easy_setopt(curl, CURLOPT_SOCKS5_AUTH, CURLAUTH_BASIC);
/* Perform the request */
curl_easy_perform(curl);
} }

HISTORY

CURLAUTH_* macros became long types in 7.26.0, prior to this version a long cast was necessary when passed to curl_easy_setopt(3).

AVAILABILITY

Added in curl 7.55.0

RETURN VALUE

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).

SEE ALSO

CURLOPT_PROXY(3), CURLOPT_PROXYTYPE(3)

2026-04-15 libcurl