CURLOPT_PORT(3) Introduction to Library Functions CURLOPT_PORT(3)

NAME

CURLOPT_PORT - remote port number to connect to

SYNOPSIS

#include <curl/curl.h>

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

DESCRIPTION

We strongly discourage using this unreliable 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 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.

DEFAULT

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

PROTOCOLS

This functionality affects all supported protocols

EXAMPLE

int main(void)
{
CURL *curl = curl_easy_init();
if(curl) {
CURLcode result;
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/foo.bin");
curl_easy_setopt(curl, CURLOPT_PORT, 8080L);
result = curl_easy_perform(curl);
curl_easy_cleanup(curl);
}
}

AVAILABILITY

Added in curl 7.1

RETURN VALUE

curl_easy_setopt(3) returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non-zero means an error
occurred, see libcurl-errors(3).

SEE ALSO

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

libcurl 2026-06-25 CURLOPT_PORT(3)