CURLOPT_PORT - Man Page

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PORT, long number);

We discourage using this option since its scope is not obvious and hard to predict. Set the preferred port number in the URL instead.

This option sets number to be the remote port number to connect to, instead of the one specified in the URL or the default port for the used protocol.

Usually, you just let the URL decide which port to use but this allows the application to override that.

While this option accepts a 'long', a port number is an unsigned 16 bit number and therefore using a port number lower than zero or over 65535 causes a CURLE_BAD_FUNCTION_ARGUMENT error.

0 which makes it not used. This also makes port number zero impossible to set with this API.

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_PORT, 8080L);
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

Added in curl 7.1

Returns CURLE_OK

CURLINFO_PRIMARY_PORT(3), CURLOPT_STDERR(3), CURLOPT_URL(3)

curl_easy_setopt(3), CURLOPT_PROXYPORT(3), libcurl-symbols(3).