CURLOPT\_ADDRESS\_SCOPE(3) Library Functions Manual CURLOPT\_ADDRESS\_SCOPE(3)

# [NAME](#NAME)

CURLOPT\_ADDRESS\_SCOPE - scope id for IPv6 addresses

# [SYNOPSIS](#SYNOPSIS)

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

# [DESCRIPTION](#DESCRIPTION)

Pass a long specifying the scope id value to use when connecting to IPv6 addresses.

# [DEFAULT](#DEFAULT)

0

# [PROTOCOLS](#PROTOCOLS)

This functionality affects all supported protocols

# [EXAMPLE](#EXAMPLE)

```
#include <net/if.h> /* for if_nametoindex() */
int main(void)
{


  CURL *curl = curl_easy_init();


  if(curl) {


    CURLcode result;


    long my_scope_id;


    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");


    my_scope_id = if_nametoindex("eth0");


    curl_easy_setopt(curl, CURLOPT_ADDRESS_SCOPE, my_scope_id);


    result = curl_easy_perform(curl);


    curl_easy_cleanup(curl);


  }
}
```

# [AVAILABILITY](#AVAILABILITY)

Added in curl 7.19.0

# [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). Returns CURLE\_BAD\_FUNCTION\_ARGUMENT if set to a negative value.

# [SEE ALSO](#SEE_ALSO)

[**CURLOPT\_DEBUGFUNCTION**(3)](/man/os/curl/CURLOPT_DEBUGFUNCTION.3), [**CURLOPT\_STDERR**(3)](/man/os/curl/CURLOPT_STDERR.3)

2026-10-31 libcurl

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