CURLOPT_PROXYPORT (3) - Linux Manuals
CURLOPT_PROXYPORT: port number the proxy listens on
NAME
CURLOPT_PROXYPORT - port number the proxy listens onSYNOPSIS
#include <curl/curl.h>CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXYPORT, long port);
DESCRIPTION
Pass a long with this option to set the proxy port to connect to unless it is specified in the proxy string CURLOPT_PROXY(3) or uses the default one.While this accepts a 'long', the port number is 16 bit so it can't be larger than 65535.