CURLOPT_LOCALPORTRANGE(3)

💅 CURLOPT_LOCALPORTRANGE(3) — the curl bestie page

okay so this is a page from the Library Functions Manual and it's literally all about CURLOPT_LOCALPORTRANGE, no cap ✨

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🌸 NAME 🌸

CURLOPT_LOCALPORTRANGE — the number of extra local ports libcurl is allowed to try, bestie 🎀

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✨ SYNOPSIS ✨

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_LOCALPORTRANGE,
                          long range);

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🦋 DESCRIPTION 🦋

so you pass a long, okay? and the range argument is the number of attempts libcurl makes to find a working local port number. it starts with whatever you gave to CURLOPT_LOCALPORT(3) and then adds one to the number for each retry 🔥

setting this option to 1 or below makes libcurl do only one try for the exact port number — like, it's not gonna go shopping around, it's just gonna commit to that one port, periodt 💀

and here's the real talk: port numbers by nature are scarce resources that are busy at times, so setting this value to something too low might cause unnecessary connection setup failures 😭 so don't be stingy with your range, okay? give it room to breathe 🫶

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👑 DEFAULT 👑

1

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🌈 PROTOCOLS 🌈

this functionality affects all supported protocols — every single one, fr fr ⭐

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

like see how it locks in 49152L as the starting port and then says "and try 20 more ports following that"? that's the vibe 💖

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💜 AVAILABILITY 💜

added in curl 7.15.2 — she's been iconic since day one 🧚

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🔥 RETURN VALUE 🔥

curl_easy_setopt(3) returns a CURLcode indicating success or error — that's the whole tea ☕

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

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🎀 SEE ALSO 🎀

• CURLOPT_INTERFACE(3)
• CURLOPT_LOCALPORT(3)

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and that's the whole page, bestie — slay, go configure your ports responsibly 💅✨

libcurl · 2026-10-12 · CURLOPT_LOCALPORTRANGE(3) — mwah, thanks for reading, ily, bye 🫶💖