CURLOPT_DNS_INTERFACE - Man Page

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DNS_INTERFACE, char *ifname);

Pass a char pointer as parameter. Set the name of the network interface that the DNS resolver should bind to. This must be an interface name (not an address). Set this option to NULL to use the default setting (do not bind to a specific interface).

The application does not have to keep the string around after setting this option.

Using this option multiple times makes the last set string override the previous ones. Set it to NULL to disable its use again.

NULL

This functionality affects all supported protocols

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/foo.bin");
    curl_easy_setopt(curl, CURLOPT_DNS_INTERFACE, "eth0");
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

This option requires that libcurl was built with a resolver backend that supports this operation. The c-ares backend is the only such one.

Added in curl 7.33.0

Returns CURLE_OK if the option is supported, CURLE_UNKNOWN_OPTION if not, or CURLE_NOT_BUILT_IN if support was disabled at compile-time.

CURLOPT_DNS_LOCAL_IP4(3), CURLOPT_DNS_LOCAL_IP6(3), CURLOPT_DNS_SERVERS(3), CURLOPT_INTERFACE(3)

curl_easy_setopt(3), CURLOPT_DNS_LOCAL_IP4(3), CURLOPT_DNS_LOCAL_IP6(3), libcurl-symbols(3).