CURLOPT_DNS_INTERFACE(3) Library Functions Manual CURLOPT_DNS_INTERFACE(3)
NAME
CURLOPT_DNS_INTERFACE - interface to speak DNS over
SYNOPSIS
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DNS_INTERFACE, char *ifname);
DESCRIPTION
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.
DEFAULT
NULL
PROTOCOLS
This functionality affects all supported protocols
EXAMPLE
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);
}
}
NOTES
This option requires that libcurl was built with a resolver backend that
supports this operation. The c-ares backend is the only such one.
AVAILABILITY
Added in curl 7.33.0
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_DNS_LOCAL_IP4(3), CURLOPT_DNS_LOCAL_IP6(3), CUR-
LOPT_DNS_SERVERS(3), CURLOPT_INTERFACE(3)
libcurl 2026-07-12 CURLOPT_DNS_INTERFACE(3)
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