CURLOPT\_SOCKS5\_GSSAPI\_NEC(3) Library Functions Manual CURLOPT\_SOCKS5\_GSSAPI\_NEC(3)

# [NAME](#NAME)

CURLOPT\_SOCKS5\_GSSAPI\_NEC - SOCKS proxy GSSAPI negotiation protection

# [SYNOPSIS](#SYNOPSIS)

```
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SOCKS5_GSSAPI_NEC, long nec);
```

# [DESCRIPTION](#DESCRIPTION)

Pass a long set to 1 to enable or 0 to disable. As part of the GSSAPI negotiation a protection mode is negotiated. The RFC 1961 says in section 4.3/4.4 it should be protected, but the NEC reference implementation does not. If enabled, this option allows the unprotected exchange of the protection mode negotiation.

# [DEFAULT](#DEFAULT)

?

# [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, "https://example.com/");


    curl_easy_setopt(curl, CURLOPT_PROXY, "socks5://proxy");


    curl_easy_setopt(curl, CURLOPT_SOCKS5_GSSAPI_NEC, 1L);


    result = curl_easy_perform(curl);


    curl_easy_cleanup(curl);


  }
}
```

# [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\_PROXY**(3)](/man/os/curl/CURLOPT_PROXY.3), [**CURLOPT\_PROXY\_SERVICE\_NAME**(3)](/man/os/curl/CURLOPT_PROXY_SERVICE_NAME.3)

2026-10-31 libcurl

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Document: CURLOPT_SOCKS5_GSSAPI_NEC(3) from curl 8.23.0-r3 (Chainguard OS)
Source: https://github.com/curl/curl.git