NAME

       CURLOPT_INTERFACE - source interface for outgoing traffic

SYNOPSIS

       #include <curl/curl.h>

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_INTERFACE, char *interface);

DESCRIPTION

       Pass  a  char  *  as  parameter.  This  sets the interface name to use as outgoing network
       interface. The name can be an interface name, an IP address, or a host name.

       If the parameter starts with "if!" then it is treated as only as  interface  name  and  no
       attempt will ever be named to do treat it as an IP address or to do name resolution on it.
       If the parameter starts with "host!" it is treated as either an IP address or a  hostname.
       Hostnames  are  resolved  synchronously.   Using the if! format is highly recommended when
       using the multi interfaces to avoid allowing the code to block.  If "if!" is specified but
       the  parameter  does  not  match an existing interface, CURLE_INTERFACE_FAILED is returned
       from the libcurl function used to perform the transfer.

       libcurl does not support using network interface names for this option on Windows.

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

DEFAULT

       NULL, use whatever the TCP stack finds suitable

PROTOCOLS

       All

EXAMPLE

       CURL *curl = curl_easy_init();
       if(curl) {
         curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/foo.bin");

         curl_easy_setopt(curl, CURLOPT_INTERFACE, "eth0");

         ret = curl_easy_perform(curl);

         curl_easy_cleanup(curl);
       }

AVAILABILITY

       The "if!" and "host!" syntax was added in 7.24.0.

RETURN VALUE

       Returns CURLE_OK on success or CURLE_OUT_OF_MEMORY if there was insufficient heap space.

SEE ALSO

       CURLOPT_SOCKOPTFUNCTION(3), CURLOPT_TCP_NODELAY(3),