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CURLOPT_INTERFACE(3) curl_easy_setopt options CURLOPT_INTERFACE(3)
CURLOPT_INTERFACE - source interface for outgoing traffic
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_INTERFACE, char
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
The application does not have to keep the string around after setting
NULL, use whatever the TCP stack finds suitable
CURL *curl = curl_easy_init();
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/foo.bin");
curl_easy_setopt(curl, CURLOPT_INTERFACE, "eth0");
ret = curl_easy_perform(curl);
The "if!" and "host!" syntax was added in 7.24.0.
Returns CURLE_OK on success or CURLE_OUT_OF_MEMORY if there was
insufficient heap space.
libcurl 7.73.0 September 16, 2020 CURLOPT_INTERFACE(3)