CURLOPT_INTERFACE(3)

1CURLOPT_INTERFACE(3)       curl_easy_setopt options       CURLOPT_INTERFACE(3)
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NAME

6       CURLOPT_INTERFACE - source interface for outgoing traffic
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SYNOPSIS

9       #include <curl/curl.h>
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11       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_INTERFACE, char *interface);
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DESCRIPTION

14       Pass a char * as parameter. This sets the interface name to use as out‐
15       going network interface. The name can be an interface name, an  IP  ad‐
16       dress, or a host name.
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18       If the parameter starts with "if!" then it is treated as only as inter‐
19       face name and no attempt will ever be named to do treat it as an IP ad‐
20       dress  or  to  do  name resolution on it.  If the parameter starts with
21       "host!" it is treated as either an IP address or a hostname.  Hostnames
22       are resolved synchronously.  Using the if! format is highly recommended
23       when using the multi interfaces to avoid allowing the  code  to  block.
24       If  "if!" is specified but the parameter does not match an existing in‐
25       terface, CURLE_INTERFACE_FAILED is returned from the  libcurl  function
26       used to perform the transfer.
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28       libcurl  does not support using network interface names for this option
29       on Windows.
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31       The application does not have to keep the string around  after  setting
32       this option.
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DEFAULT

35       NULL, use whatever the TCP stack finds suitable
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PROTOCOLS

38       All
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EXAMPLE

41       CURL *curl = curl_easy_init();
42       if(curl) {
43         curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/foo.bin");
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45         curl_easy_setopt(curl, CURLOPT_INTERFACE, "eth0");
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47         ret = curl_easy_perform(curl);
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49         curl_easy_cleanup(curl);
50       }
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AVAILABILITY

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

56       Returns  CURLE_OK on success or CURLE_OUT_OF_MEMORY if there was insuf‐
57       ficient heap space.
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