CURLOPT_PR...H_USERNAME(3)

💅 CURLOPT_PROXY_TLSAUTH_USERNAME(3) — the glam little page from libcurl's Library Functions Manual

okay so bestie, picture this: you're doing TLS auth to a proxy (yes, a proxy, not the server, keep up ✨) and the proxy wants a username. That's literally what this option is for. It's the proxy-side sibling of the regular TLS auth username, and she's giving "supporting character but make it essential" energy. 🎀

Heads up, the header of this page gets truncated to CURLOPT_PR...H_USERNAME(3) because the name is lowkey too long for the man page column, but you and I both know what she's called. 👑

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✨ NAME ✨

CURLOPT_PROXY_TLSAUTH_USERNAME — the username to use for proxy TLS authentication 🫶

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🌸 SYNOPSIS 🌸

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXY_TLSAUTH_USERNAME,
                          char *user);

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🦋 DESCRIPTION 🦋

So you pass a char pointer as the parameter, and it should point to a null-terminated username string. That string is what gets used for the HTTPS proxy TLS authentication method you picked over in CURLOPT_PROXY_TLSAUTH_TYPE(3). 🌈

Big requirement though: this option needs CURLOPT_PROXY_TLSAUTH_PASSWORD(3) to also be set. It's a two-piece outfit, you can't wear just the top. 💀

Good news for your memory management anxiety: the application does not have to keep the string around after setting this option. Set it and forget it, she's copied. ✨

And if you're the type to set this multiple times (no judgement, we've all been there 🙈): the last set string overrides the previous ones. Setting it to NULL disables its use again, like a clean slate moment. 💜

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🎀 DEFAULT 🎀

NULL

(no username, no proxy TLS auth username-ing, that's the vibe)

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🔥 PROTOCOLS 🔥

This functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc. Basically if it's got an S on the end and TLS in its soul, she's in. ⭐

⚠️ but here's the catch, bestie: this option works only with the following TLS backends: GnuTLS and OpenSSL. If you're on a different backend, this is not your moment. 😭

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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/");
    curl_easy_setopt(curl, CURLOPT_PROXY, "https://proxy.example");
    curl_easy_setopt(curl, CURLOPT_PROXY_TLSAUTH_TYPE, "SRP");
    curl_easy_setopt(curl, CURLOPT_PROXY_TLSAUTH_USERNAME, "user");
    curl_easy_setopt(curl, CURLOPT_PROXY_TLSAUTH_PASSWORD, "secret");
    result = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

look at her. URL set, proxy set, SRP chosen, username "user", password "secret", perform, cleanup. The whole little routine, no cap. 🧚

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💖 AVAILABILITY 💖

Added in curl 7.52.0 — so she's been iconic since 2016, iykyk. 👑

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🍓 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 — go check libcurl-errors(3) for the tea. 🔍

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🌈 SEE ALSO 🌈

• CURLOPT_PROXY_TLSAUTH_PASSWORD(3)
• CURLOPT_PROXY_TLSAUTH_TYPE(3)
• CURLOPT_TLSAUTH_PASSWORD(3)
• CURLOPT_TLSAUTH_TYPE(3)

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and that's the page, bestie 🫶 mwah 💋

🌸 sign-off szn: this gem is from libcurl, dated 2026-10-12, and its footer name is the ever-truncated CURLOPT_PR...H_USERNAME(3). periodt. ✨