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Sortix volatile manual

This manual documents Sortix volatile, a development build that has not been officially released. You can instead view this document in the latest official manual.

CURLOPT_LOCALPORT(3) Library Functions Manual CURLOPT_LOCALPORT(3)

NAME

CURLOPT_LOCALPORT - local port number to use for socket

SYNOPSIS


#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_LOCALPORT, long port);

DESCRIPTION

Pass a long. This sets the local port number of the socket used for the connection. This can be used in combination with CURLOPT_INTERFACE(3) and you are recommended to use CURLOPT_LOCALPORTRANGE(3) as well when this option is set. Valid port numbers are 1 - 65535.

DEFAULT

0, disabled - use whatever the system thinks is fine

PROTOCOLS

This functionality affects all supported protocols

EXAMPLE


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_LOCALPORT, 49152L);
/* and try 20 more ports following that */
curl_easy_setopt(curl, CURLOPT_LOCALPORTRANGE, 20L);
res = curl_easy_perform(curl);
curl_easy_cleanup(curl);
}
}

AVAILABILITY

Added in curl 7.15.2

RETURN VALUE

Returns CURLE_OK

SEE ALSO

CURLINFO_LOCAL_PORT(3), CURLOPT_INTERFACE(3), CURLOPT_LOCALPORTRANGE(3)
2025-06-06 libcurl
Copyright 2011-2025 Jonas 'Sortie' Termansen and contributors.
Sortix's source code is free software under the ISC license.
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