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Re: Improve Error Handling message to become user friendly
- Contemporary messages sorted: [ by date ] [ by thread ] [ by subject ] [ by author ] [ by messages with attachments ]
From: Aleksandar Lazic via curl-users <curl-users_at_lists.haxx.se>
Date: Fri, 15 Aug 2025 10:46:57 +0200
Hi "cyber security".
On 2025-08-15 (Fr.) 10:30, cyber security via curl-users wrote:
> Hello, Daniel Stenberg and the curl team.
>
> I suggest today improve error message for become user friendly:
Feel free to contribute ( https://github.com/curl/curl?tab=contributing-ov-file
) to the Project.
Regards
Aleks
> ┌──(relun㉿relunsec)-[~/Test]
> └─$ curl https://127.0.0.0.1.1 <https://127.0.0.0.1.1>
> curl: (6) Could not resolve host: 127.0.0.0.1.1
>
> ┌──(relun㉿relunsec)-[~/Test]
> └─$
>
> example provide a user friendly error message check first ip and next do dns
> resolution ┌──(relun㉿relunsec)-[~/Test]
> └─$ curl https://127.0.0.0.1.1 <https://127.0.0.0.1.1>
> curl: (6) Failed to parse the ip 127.0.0.0.1.1 excepted. must have 4 octets
> (e.g, 127.0.0.1).
>
> ┌──(relun㉿relunsec)-[~/Test]
> └─$ also example
> ┌──(relun㉿relunsec)-[~/Test]
> └─$ curl -6 http://127.0.0.1 <http://127.0.0.1>
> curl: (7) Could not connect to server
>
> ┌──(relun㉿relunsec)-[~/Test]
> └─$ improve it to ┌──(relun㉿relunsec)-[~/Test]
> └─$ curl -6 http://127.0.0.1 <http://127.0.0.1>
> curl: (7) This not valid IPv6. It seems ipv4 tries to remove -6.
>
> ┌──(relun㉿relunsec)-[~/Test]
> └─$
>
> here parse the IP is ipv4 and provide different error message examples like
> "curl: (7) This not valid IPv6. It seems ipv4 tries to remove -6." if not valid
> ipv6 or ipv4 fail to "curl: (7) Could not connect to server"
>
> example also ┌──(relun㉿relunsec)-[~/Test]
> └─$ curl https://httpbin.org <https://httpbin.org> --tls-max 1
> curl: option --tls-max: is badly used here
> curl: try 'curl --help' or 'curl --manual' for more information
>
> ┌──(relun㉿relunsec)-[~/Test]
> └─$
>
> improve it to ┌──(relun㉿relunsec)-[~/Test]
> └─$ curl https://httpbin.org <https://httpbin.org> --tls-max 1
> curl: option --tls-max: Invalid TLS Version choose from 1.0,1.1,1.2,1.3
> curl: try 'curl --help' or 'curl --manual' for more information
>
> ┌──(relun㉿relunsec)-[~/Test]
> └─$ here suggest valid TLS Version
>
> and also same for └─$ curl https://httpbin.org <https://httpbin.org> --ftp-ssl-
> ccc-mode activea
> Warning: unrecognized ftp CCC method 'activea', using default
> <!DOCTYPE html>
> <html lang="en">
>
> <head>
> <meta charset="UTF-8">
> <title>httpbin.org <http://httpbin.org></title>
> <link href="https://fonts.googleapis.com/css?family=Open+Sans:400,700|
> Source+Code+Pro:300,600|Titillium+Web:400,600,700 <https://fonts.googleapis.com/
> css?family=Open+Sans:400,700|Source+Code+Pro:300,600|Titillium+Web:400,600,700>"
> rel="stylesheet">
> <link rel="stylesheet" type="text/css" href="/flasgger_static/swagger-ui.css">
> <link rel="icon" type="image/png" href="/static/favicon.ico" sizes="64x64
> 32x32 16x16" />
> <style>
> html {
> box-sizing: border-box;
> overflow: -moz-scrollbars-vertical;
> overflow-y: scroll;
> }
>
> *,
> *:before,
> *:after {
> box-sizing: inherit;
> }
>
> body {
> margin: 0;
> background: #fafafa;
> }
> </style>
> </head>
>
> <body>
> <a href="https://github.com/requests/httpbin <https://github.com/requests/
> httpbin>" class="github-corner" aria-label="View source on Github">
> <svg width="80" height="80" viewBox="0 0 250 250" style="fill:#151513;
> color:#fff; position: absolute; top: 0; border: 0; right: 0;"
> aria-hidden="true">
> <path d="M0,0 L115,115 L130,115 L142,142 L250,250 L250,0 Z"></path>
> <path d="M128.3,109.0 C113.8,99.7 119.0,89.6 119.0,89.6 C122.0,82.7
> 120.5,78.6 120.5,78.6 C119.2,72.0 123.4,76.3 123.4,76.3 C127.3,80.9 125.5,87.3
> 125.5,87.3 C122.9,97.6 130.6,101.9 134.4,103.2"
> fill="currentColor" style="transform-origin: 130px 106px;"
> class="octo-arm"></path>
> <path d="M115.0,115.0 C114.9,115.1 118.7,116.5 119.8,115.4
> L133.7,101.6 C136.9,99.2 139.9,98.4 142.2,98.6 C133.8,88.0 127.5,74.4 143.8,58.0
> C148.5,53.4 154.0,51.2 159.7,51.0 C160.3,49.4 163.2,43.6 171.4,40.1 C171.4,40.1
> 176.1,42.5 178.8,56.2 C183.1,58.6 187.2,61.8 190.9,65.4 C194.5,69.0 197.7,73.2
> 200.1,77.6 C213.8,80.2 216.3,84.9 216.3,84.9 C212.7,93.1 206.9,96.0 205.4,96.6
> C205.1,102.4 203.0,107.8 198.3,112.5 C181.9,128.9 168.3,122.5 157.7,114.1
> C157.9,116.9 156.7,120.9 152.7,124.9 L141.0,136.5 C139.8,137.7 141.6,141.9
> 141.8,141.8 Z"
> fill="currentColor" class="octo-body"></path>
> </svg>
> </a>
> <svg xmlns="http://www.w3.org/2000/svg <http://www.w3.org/2000/svg>"
> xmlns:xlink="http://www.w3.org/1999/xlink <http://www.w3.org/1999/xlink>"
> style="position:absolute;width:0;height:0">
> <defs>
> <symbol viewBox="0 0 20 20" id="unlocked">
> <path d="M15.8 8H14V5.6C14 2.703 12.665 1 10 1 7.334 1 6 2.703
> 6 5.6V6h2v-.801C8 3.754 8.797 3 10 3c1.203 0 2 .754 2 2.199V8H4c-.553 0-1 .646-1
> 1.199V17c0 .549.428 1.139.951 1.307l1.197.387C5.672 18.861 6.55 19 7.1
> 19h5.8c.549 0 1.428-.139
> 1.951-.307l1.196-.387c.524-.167.953-.757.953-1.306V9.199C17 8.646 16.352 8 15.8
> 8z"></path>
> </symbol>
>
> <symbol viewBox="0 0 20 20" id="locked">
> <path d="M15.8 8H14V5.6C14 2.703 12.665 1 10 1 7.334 1 6 2.703
> 6 5.6V8H4c-.553 0-1 .646-1 1.199V17c0 .549.428 1.139.951 1.307l1.197.387C5.672
> 18.861 6.55 19 7.1 19h5.8c.549 0 1.428-.139
> 1.951-.307l1.196-.387c.524-.167.953-.757.953-1.306V9.199C17 8.646 16.352 8 15.8
> 8zM12 8H8V5.199C8 3.754 8.797 3 10 3c1.203 0 2 .754 2 2.199V8z"
> />
> </symbol>
>
> <symbol viewBox="0 0 20 20" id="close">
> <path d="M14.348 14.849c-.469.469-1.229.469-1.697 0L10
> 11.819l-2.651 3.029c-.469.469-1.229.469-1.697 0-.469-.469-.469-1.229
> 0-1.697l2.758-3.15-2.759-3.152c-.469-.469-.469-1.228 0-1.697.469-.469 1.228-.469
> 1.697 0L10 8.183l2.651-3.031c.469-.469 1.228-.469 1.697 0 .469.469.469 1.229 0
> 1.697l-2.758 3.152 2.758 3.15c.469.469.469 1.229 0 1.698z"
> />
> </symbol>
>
> <symbol viewBox="0 0 20 20" id="large-arrow">
> <path d="M13.25 10L6.109 2.58c-.268-.27-.268-.707
> 0-.979.268-.27.701-.27.969 0l7.83 7.908c.268.271.268.709 0 .979l-7.83
> 7.908c-.268.271-.701.27-.969 0-.268-.269-.268-.707 0-.979L13.25 10z"
> />
> </symbol>
>
> <symbol viewBox="0 0 20 20" id="large-arrow-down">
> <path d="M17.418 6.109c.272-.268.709-.268.979 0s.271.701
> 0 .969l-7.908 7.83c-.27.268-.707.268-.979 0l-7.908-7.83c-.27-.268-.27-.701
> 0-.969.271-.268.709-.268.979 0L10 13.25l7.418-7.141z"
> />
> </symbol>
>
>
> <symbol viewBox="0 0 24 24" id="jump-to">
> <path d="M19 7v4H5.83l3.58-3.59L8 6l-6 6 6 6 1.41-1.41L5.83
> 13H21V7z" />
> </symbol>
>
> <symbol viewBox="0 0 24 24" id="expand">
> <path d="M10 18h4v-2h-4v2zM3 6v2h18V6H3zm3 7h12v-2H6v2z" />
> </symbol>
>
> </defs>
> </svg>
>
>
> <div id="swagger-ui">
> <div data-reactroot="" class="swagger-ui">
> <div>
> <div class="information-container wrapper">
> <section class="block col-12">
> <div class="info">
> <hgroup class="main">
> <h2 class="title">httpbin.org <http://httpbin.org>
> <small>
> <pre class="version">0.9.2</pre>
> </small>
> </h2>
> <pre class="base-url">[ Base URL: httpbin.org/
> <http://httpbin.org/> ]</pre>
> </hgroup>
> <div class="description">
> <div class="markdown">
> <p>A simple HTTP Request & Response
> Service.
> <br>
> <br>
> <b>Run locally: </b>
> <code>$ docker run -p 80:80
> kennethreitz/httpbin</code>
> </p>
> </div>
> </div>
> <div>
> <div>
> <a href="https://kennethreitz.org <https://
> kennethreitz.org>" target="_blank">the developer - Website</a>
> </div>
> <a href="mailto:me_at_kennethreitz.org
> <mailto:me_at_kennethreitz.org>">Send email to the developer</a>
> </div>
> </div>
> <!-- ADDS THE LOADER SPINNER -->
> <div class="loading-container">
> <div class="loading"></div>
> </div>
>
> </section>
> </div>
> </div>
> </div>
> </div>
>
>
> <div class='swagger-ui'>
> <div class="wrapper">
> <section class="clear">
> <span style="float: right;">
> [Powered by
> <a target="_blank" href="https://github.com/rochacbruno/
> flasgger <https://github.com/rochacbruno/flasgger>">Flasgger</a>]
> <br>
> </span>
> </section>
> </div>
> </div>
>
>
>
> <script src="/flasgger_static/swagger-ui-bundle.js"> </script>
> <script src="/flasgger_static/swagger-ui-standalone-preset.js"> </script>
> <script src='/flasgger_static/lib/jquery.min.js' type='text/javascript'></
> script>
> <script>
>
> window.onload = function () {
>
>
> fetch("/spec.json")
> .then(function (response) {
> response.json()
> .then(function (json) {
> var current_protocol =
> window.location.protocol.slice(0, -1);
> if (json.schemes[0] != current_protocol) {
> // Switches scheme to the current in use
> var other_protocol = json.schemes[0];
> json.schemes[0] = current_protocol;
> json.schemes[1] = other_protocol;
>
> }
> json.host = window.location.host; // sets the
> current host
>
> const ui = SwaggerUIBundle({
> spec: json,
> validatorUrl: null,
> dom_id: '#swagger-ui',
> deepLinking: true,
> jsonEditor: true,
> docExpansion: "none",
> apisSorter: "alpha",
> //operationsSorter: "alpha",
> presets: [
> SwaggerUIBundle.presets.apis,
> // yay ES6 modules ↘
> Array.isArray(SwaggerUIStandalonePreset) ?
> SwaggerUIStandalonePreset : SwaggerUIStandalonePreset.default
> ],
> plugins: [
> SwaggerUIBundle.plugins.DownloadUrl
> ],
>
> // layout: "StandaloneLayout" // uncomment to enable the green top
> header
> })
>
> window.ui = ui
>
> // uncomment to rename the top brand if layout is enabled
> // $(".topbar-wrapper .link span").replaceWith("<span>httpbin</span>");
> })
> })
> }
> </script> <div class='swagger-ui'>
> <div class="wrapper">
> <section class="block col-12 block-desktop col-12-desktop">
> <div>
>
> <h2>Other Utilities</h2>
>
> <ul>
> <li>
> <a href="/forms/post">HTML form</a> that posts to /
> post /forms/post</li>
> </ul>
>
> <br />
> <br />
> </div>
> </section>
> </div>
> </div>
> </body>
>
> </html>
> ┌──(relun㉿relunsec)-[~/Test]
> └─$
>
> improve it to └─$ curl https://httpbin.org <https://httpbin.org> --ftp-ssl-ccc-
> mode activea
> Warning: unrecognized ftp CCC method 'activea' choose from 'active' and
> 'passive', using default
> <!DOCTYPE html>
> <html lang="en">
>
> <head>
> <meta charset="UTF-8">
> <title>httpbin.org <http://httpbin.org></title>
> <link href="https://fonts.googleapis.com/css?family=Open+Sans:400,700|
> Source+Code+Pro:300,600|Titillium+Web:400,600,700 <https://fonts.googleapis.com/
> css?family=Open+Sans:400,700|Source+Code+Pro:300,600|Titillium+Web:400,600,700>"
> rel="stylesheet">
> <link rel="stylesheet" type="text/css" href="/flasgger_static/swagger-ui.css">
> <link rel="icon" type="image/png" href="/static/favicon.ico" sizes="64x64
> 32x32 16x16" />
> <style>
> html {
> box-sizing: border-box;
> overflow: -moz-scrollbars-vertical;
> overflow-y: scroll;
> }
>
> *,
> *:before,
> *:after {
> box-sizing: inherit;
> }
>
> body {
> margin: 0;
> background: #fafafa;
> }
> </style>
> </head>
>
> <body>
> <a href="https://github.com/requests/httpbin <https://github.com/requests/
> httpbin>" class="github-corner" aria-label="View source on Github">
> <svg width="80" height="80" viewBox="0 0 250 250" style="fill:#151513;
> color:#fff; position: absolute; top: 0; border: 0; right: 0;"
> aria-hidden="true">
> <path d="M0,0 L115,115 L130,115 L142,142 L250,250 L250,0 Z"></path>
> <path d="M128.3,109.0 C113.8,99.7 119.0,89.6 119.0,89.6 C122.0,82.7
> 120.5,78.6 120.5,78.6 C119.2,72.0 123.4,76.3 123.4,76.3 C127.3,80.9 125.5,87.3
> 125.5,87.3 C122.9,97.6 130.6,101.9 134.4,103.2"
> fill="currentColor" style="transform-origin: 130px 106px;"
> class="octo-arm"></path>
> <path d="M115.0,115.0 C114.9,115.1 118.7,116.5 119.8,115.4
> L133.7,101.6 C136.9,99.2 139.9,98.4 142.2,98.6 C133.8,88.0 127.5,74.4 143.8,58.0
> C148.5,53.4 154.0,51.2 159.7,51.0 C160.3,49.4 163.2,43.6 171.4,40.1 C171.4,40.1
> 176.1,42.5 178.8,56.2 C183.1,58.6 187.2,61.8 190.9,65.4 C194.5,69.0 197.7,73.2
> 200.1,77.6 C213.8,80.2 216.3,84.9 216.3,84.9 C212.7,93.1 206.9,96.0 205.4,96.6
> C205.1,102.4 203.0,107.8 198.3,112.5 C181.9,128.9 168.3,122.5 157.7,114.1
> C157.9,116.9 156.7,120.9 152.7,124.9 L141.0,136.5 C139.8,137.7 141.6,141.9
> 141.8,141.8 Z"
> fill="currentColor" class="octo-body"></path>
> </svg>
> </a>
> <svg xmlns="http://www.w3.org/2000/svg <http://www.w3.org/2000/svg>"
> xmlns:xlink="http://www.w3.org/1999/xlink <http://www.w3.org/1999/xlink>"
> style="position:absolute;width:0;height:0">
> <defs>
> <symbol viewBox="0 0 20 20" id="unlocked">
> <path d="M15.8 8H14V5.6C14 2.703 12.665 1 10 1 7.334 1 6 2.703
> 6 5.6V6h2v-.801C8 3.754 8.797 3 10 3c1.203 0 2 .754 2 2.199V8H4c-.553 0-1 .646-1
> 1.199V17c0 .549.428 1.139.951 1.307l1.197.387C5.672 18.861 6.55 19 7.1
> 19h5.8c.549 0 1.428-.139
> 1.951-.307l1.196-.387c.524-.167.953-.757.953-1.306V9.199C17 8.646 16.352 8 15.8
> 8z"></path>
> </symbol>
>
> <symbol viewBox="0 0 20 20" id="locked">
> <path d="M15.8 8H14V5.6C14 2.703 12.665 1 10 1 7.334 1 6 2.703
> 6 5.6V8H4c-.553 0-1 .646-1 1.199V17c0 .549.428 1.139.951 1.307l1.197.387C5.672
> 18.861 6.55 19 7.1 19h5.8c.549 0 1.428-.139
> 1.951-.307l1.196-.387c.524-.167.953-.757.953-1.306V9.199C17 8.646 16.352 8 15.8
> 8zM12 8H8V5.199C8 3.754 8.797 3 10 3c1.203 0 2 .754 2 2.199V8z"
> />
> </symbol>
>
> <symbol viewBox="0 0 20 20" id="close">
> <path d="M14.348 14.849c-.469.469-1.229.469-1.697 0L10
> 11.819l-2.651 3.029c-.469.469-1.229.469-1.697 0-.469-.469-.469-1.229
> 0-1.697l2.758-3.15-2.759-3.152c-.469-.469-.469-1.228 0-1.697.469-.469 1.228-.469
> 1.697 0L10 8.183l2.651-3.031c.469-.469 1.228-.469 1.697 0 .469.469.469 1.229 0
> 1.697l-2.758 3.152 2.758 3.15c.469.469.469 1.229 0 1.698z"
> />
> </symbol>
>
> <symbol viewBox="0 0 20 20" id="large-arrow">
> <path d="M13.25 10L6.109 2.58c-.268-.27-.268-.707
> 0-.979.268-.27.701-.27.969 0l7.83 7.908c.268.271.268.709 0 .979l-7.83
> 7.908c-.268.271-.701.27-.969 0-.268-.269-.268-.707 0-.979L13.25 10z"
> />
> </symbol>
>
> <symbol viewBox="0 0 20 20" id="large-arrow-down">
> <path d="M17.418 6.109c.272-.268.709-.268.979 0s.271.701
> 0 .969l-7.908 7.83c-.27.268-.707.268-.979 0l-7.908-7.83c-.27-.268-.27-.701
> 0-.969.271-.268.709-.268.979 0L10 13.25l7.418-7.141z"
> />
> </symbol>
>
>
> <symbol viewBox="0 0 24 24" id="jump-to">
> <path d="M19 7v4H5.83l3.58-3.59L8 6l-6 6 6 6 1.41-1.41L5.83
> 13H21V7z" />
> </symbol>
>
> <symbol viewBox="0 0 24 24" id="expand">
> <path d="M10 18h4v-2h-4v2zM3 6v2h18V6H3zm3 7h12v-2H6v2z" />
> </symbol>
>
> </defs>
> </svg>
>
>
> <div id="swagger-ui">
> <div data-reactroot="" class="swagger-ui">
> <div>
> <div class="information-container wrapper">
> <section class="block col-12">
> <div class="info">
> <hgroup class="main">
> <h2 class="title">httpbin.org <http://httpbin.org>
> <small>
> <pre class="version">0.9.2</pre>
> </small>
> </h2>
> <pre class="base-url">[ Base URL: httpbin.org/
> <http://httpbin.org/> ]</pre>
> </hgroup>
> <div class="description">
> <div class="markdown">
> <p>A simple HTTP Request & Response
> Service.
> <br>
> <br>
> <b>Run locally: </b>
> <code>$ docker run -p 80:80
> kennethreitz/httpbin</code>
> </p>
> </div>
> </div>
> <div>
> <div>
> <a href="https://kennethreitz.org <https://
> kennethreitz.org>" target="_blank">the developer - Website</a>
> </div>
> <a href="mailto:me_at_kennethreitz.org
> <mailto:me_at_kennethreitz.org>">Send email to the developer</a>
> </div>
> </div>
> <!-- ADDS THE LOADER SPINNER -->
> <div class="loading-container">
> <div class="loading"></div>
> </div>
>
> </section>
> </div>
> </div>
> </div>
> </div>
>
>
> <div class='swagger-ui'>
> <div class="wrapper">
> <section class="clear">
> <span style="float: right;">
> [Powered by
> <a target="_blank" href="https://github.com/rochacbruno/
> flasgger <https://github.com/rochacbruno/flasgger>">Flasgger</a>]
> <br>
> </span>
> </section>
> </div>
> </div>
>
>
>
> <script src="/flasgger_static/swagger-ui-bundle.js"> </script>
> <script src="/flasgger_static/swagger-ui-standalone-preset.js"> </script>
> <script src='/flasgger_static/lib/jquery.min.js' type='text/javascript'></
> script>
> <script>
>
> window.onload = function () {
>
>
> fetch("/spec.json")
> .then(function (response) {
> response.json()
> .then(function (json) {
> var current_protocol =
> window.location.protocol.slice(0, -1);
> if (json.schemes[0] != current_protocol) {
> // Switches scheme to the current in use
> var other_protocol = json.schemes[0];
> json.schemes[0] = current_protocol;
> json.schemes[1] = other_protocol;
>
> }
> json.host = window.location.host; // sets the
> current host
>
> const ui = SwaggerUIBundle({
> spec: json,
> validatorUrl: null,
> dom_id: '#swagger-ui',
> deepLinking: true,
> jsonEditor: true,
> docExpansion: "none",
> apisSorter: "alpha",
> //operationsSorter: "alpha",
> presets: [
> SwaggerUIBundle.presets.apis,
> // yay ES6 modules ↘
> Array.isArray(SwaggerUIStandalonePreset) ?
> SwaggerUIStandalonePreset : SwaggerUIStandalonePreset.default
> ],
> plugins: [
> SwaggerUIBundle.plugins.DownloadUrl
> ],
>
> // layout: "StandaloneLayout" // uncomment to enable the green top
> header
> })
>
> window.ui = ui
>
> // uncomment to rename the top brand if layout is enabled
> // $(".topbar-wrapper .link span").replaceWith("<span>httpbin</span>");
> })
> })
> }
> </script> <div class='swagger-ui'>
> <div class="wrapper">
> <section class="block col-12 block-desktop col-12-desktop">
> <div>
>
> <h2>Other Utilities</h2>
>
> <ul>
> <li>
> <a href="/forms/post">HTML form</a> that posts to /
> post /forms/post</li>
> </ul>
>
> <br />
> <br />
> </div>
> </section>
> </div>
> </div>
> </body>
>
> </html>
> ┌──(relun㉿relunsec)-[~/Test]
> └─$
>
> and also you can improve other error messages you can adjust if you would.
>
> Dear
>
> RelunSec
>
>
>
>
Date: Fri, 15 Aug 2025 10:46:57 +0200
Hi "cyber security".
On 2025-08-15 (Fr.) 10:30, cyber security via curl-users wrote:
> Hello, Daniel Stenberg and the curl team.
>
> I suggest today improve error message for become user friendly:
Feel free to contribute ( https://github.com/curl/curl?tab=contributing-ov-file
) to the Project.
Regards
Aleks
> ┌──(relun㉿relunsec)-[~/Test]
> └─$ curl https://127.0.0.0.1.1 <https://127.0.0.0.1.1>
> curl: (6) Could not resolve host: 127.0.0.0.1.1
>
> ┌──(relun㉿relunsec)-[~/Test]
> └─$
>
> example provide a user friendly error message check first ip and next do dns
> resolution ┌──(relun㉿relunsec)-[~/Test]
> └─$ curl https://127.0.0.0.1.1 <https://127.0.0.0.1.1>
> curl: (6) Failed to parse the ip 127.0.0.0.1.1 excepted. must have 4 octets
> (e.g, 127.0.0.1).
>
> ┌──(relun㉿relunsec)-[~/Test]
> └─$ also example
> ┌──(relun㉿relunsec)-[~/Test]
> └─$ curl -6 http://127.0.0.1 <http://127.0.0.1>
> curl: (7) Could not connect to server
>
> ┌──(relun㉿relunsec)-[~/Test]
> └─$ improve it to ┌──(relun㉿relunsec)-[~/Test]
> └─$ curl -6 http://127.0.0.1 <http://127.0.0.1>
> curl: (7) This not valid IPv6. It seems ipv4 tries to remove -6.
>
> ┌──(relun㉿relunsec)-[~/Test]
> └─$
>
> here parse the IP is ipv4 and provide different error message examples like
> "curl: (7) This not valid IPv6. It seems ipv4 tries to remove -6." if not valid
> ipv6 or ipv4 fail to "curl: (7) Could not connect to server"
>
> example also ┌──(relun㉿relunsec)-[~/Test]
> └─$ curl https://httpbin.org <https://httpbin.org> --tls-max 1
> curl: option --tls-max: is badly used here
> curl: try 'curl --help' or 'curl --manual' for more information
>
> ┌──(relun㉿relunsec)-[~/Test]
> └─$
>
> improve it to ┌──(relun㉿relunsec)-[~/Test]
> └─$ curl https://httpbin.org <https://httpbin.org> --tls-max 1
> curl: option --tls-max: Invalid TLS Version choose from 1.0,1.1,1.2,1.3
> curl: try 'curl --help' or 'curl --manual' for more information
>
> ┌──(relun㉿relunsec)-[~/Test]
> └─$ here suggest valid TLS Version
>
> and also same for └─$ curl https://httpbin.org <https://httpbin.org> --ftp-ssl-
> ccc-mode activea
> Warning: unrecognized ftp CCC method 'activea', using default
> <!DOCTYPE html>
> <html lang="en">
>
> <head>
> <meta charset="UTF-8">
> <title>httpbin.org <http://httpbin.org></title>
> <link href="https://fonts.googleapis.com/css?family=Open+Sans:400,700|
> Source+Code+Pro:300,600|Titillium+Web:400,600,700 <https://fonts.googleapis.com/
> css?family=Open+Sans:400,700|Source+Code+Pro:300,600|Titillium+Web:400,600,700>"
> rel="stylesheet">
> <link rel="stylesheet" type="text/css" href="/flasgger_static/swagger-ui.css">
> <link rel="icon" type="image/png" href="/static/favicon.ico" sizes="64x64
> 32x32 16x16" />
> <style>
> html {
> box-sizing: border-box;
> overflow: -moz-scrollbars-vertical;
> overflow-y: scroll;
> }
>
> *,
> *:before,
> *:after {
> box-sizing: inherit;
> }
>
> body {
> margin: 0;
> background: #fafafa;
> }
> </style>
> </head>
>
> <body>
> <a href="https://github.com/requests/httpbin <https://github.com/requests/
> httpbin>" class="github-corner" aria-label="View source on Github">
> <svg width="80" height="80" viewBox="0 0 250 250" style="fill:#151513;
> color:#fff; position: absolute; top: 0; border: 0; right: 0;"
> aria-hidden="true">
> <path d="M0,0 L115,115 L130,115 L142,142 L250,250 L250,0 Z"></path>
> <path d="M128.3,109.0 C113.8,99.7 119.0,89.6 119.0,89.6 C122.0,82.7
> 120.5,78.6 120.5,78.6 C119.2,72.0 123.4,76.3 123.4,76.3 C127.3,80.9 125.5,87.3
> 125.5,87.3 C122.9,97.6 130.6,101.9 134.4,103.2"
> fill="currentColor" style="transform-origin: 130px 106px;"
> class="octo-arm"></path>
> <path d="M115.0,115.0 C114.9,115.1 118.7,116.5 119.8,115.4
> L133.7,101.6 C136.9,99.2 139.9,98.4 142.2,98.6 C133.8,88.0 127.5,74.4 143.8,58.0
> C148.5,53.4 154.0,51.2 159.7,51.0 C160.3,49.4 163.2,43.6 171.4,40.1 C171.4,40.1
> 176.1,42.5 178.8,56.2 C183.1,58.6 187.2,61.8 190.9,65.4 C194.5,69.0 197.7,73.2
> 200.1,77.6 C213.8,80.2 216.3,84.9 216.3,84.9 C212.7,93.1 206.9,96.0 205.4,96.6
> C205.1,102.4 203.0,107.8 198.3,112.5 C181.9,128.9 168.3,122.5 157.7,114.1
> C157.9,116.9 156.7,120.9 152.7,124.9 L141.0,136.5 C139.8,137.7 141.6,141.9
> 141.8,141.8 Z"
> fill="currentColor" class="octo-body"></path>
> </svg>
> </a>
> <svg xmlns="http://www.w3.org/2000/svg <http://www.w3.org/2000/svg>"
> xmlns:xlink="http://www.w3.org/1999/xlink <http://www.w3.org/1999/xlink>"
> style="position:absolute;width:0;height:0">
> <defs>
> <symbol viewBox="0 0 20 20" id="unlocked">
> <path d="M15.8 8H14V5.6C14 2.703 12.665 1 10 1 7.334 1 6 2.703
> 6 5.6V6h2v-.801C8 3.754 8.797 3 10 3c1.203 0 2 .754 2 2.199V8H4c-.553 0-1 .646-1
> 1.199V17c0 .549.428 1.139.951 1.307l1.197.387C5.672 18.861 6.55 19 7.1
> 19h5.8c.549 0 1.428-.139
> 1.951-.307l1.196-.387c.524-.167.953-.757.953-1.306V9.199C17 8.646 16.352 8 15.8
> 8z"></path>
> </symbol>
>
> <symbol viewBox="0 0 20 20" id="locked">
> <path d="M15.8 8H14V5.6C14 2.703 12.665 1 10 1 7.334 1 6 2.703
> 6 5.6V8H4c-.553 0-1 .646-1 1.199V17c0 .549.428 1.139.951 1.307l1.197.387C5.672
> 18.861 6.55 19 7.1 19h5.8c.549 0 1.428-.139
> 1.951-.307l1.196-.387c.524-.167.953-.757.953-1.306V9.199C17 8.646 16.352 8 15.8
> 8zM12 8H8V5.199C8 3.754 8.797 3 10 3c1.203 0 2 .754 2 2.199V8z"
> />
> </symbol>
>
> <symbol viewBox="0 0 20 20" id="close">
> <path d="M14.348 14.849c-.469.469-1.229.469-1.697 0L10
> 11.819l-2.651 3.029c-.469.469-1.229.469-1.697 0-.469-.469-.469-1.229
> 0-1.697l2.758-3.15-2.759-3.152c-.469-.469-.469-1.228 0-1.697.469-.469 1.228-.469
> 1.697 0L10 8.183l2.651-3.031c.469-.469 1.228-.469 1.697 0 .469.469.469 1.229 0
> 1.697l-2.758 3.152 2.758 3.15c.469.469.469 1.229 0 1.698z"
> />
> </symbol>
>
> <symbol viewBox="0 0 20 20" id="large-arrow">
> <path d="M13.25 10L6.109 2.58c-.268-.27-.268-.707
> 0-.979.268-.27.701-.27.969 0l7.83 7.908c.268.271.268.709 0 .979l-7.83
> 7.908c-.268.271-.701.27-.969 0-.268-.269-.268-.707 0-.979L13.25 10z"
> />
> </symbol>
>
> <symbol viewBox="0 0 20 20" id="large-arrow-down">
> <path d="M17.418 6.109c.272-.268.709-.268.979 0s.271.701
> 0 .969l-7.908 7.83c-.27.268-.707.268-.979 0l-7.908-7.83c-.27-.268-.27-.701
> 0-.969.271-.268.709-.268.979 0L10 13.25l7.418-7.141z"
> />
> </symbol>
>
>
> <symbol viewBox="0 0 24 24" id="jump-to">
> <path d="M19 7v4H5.83l3.58-3.59L8 6l-6 6 6 6 1.41-1.41L5.83
> 13H21V7z" />
> </symbol>
>
> <symbol viewBox="0 0 24 24" id="expand">
> <path d="M10 18h4v-2h-4v2zM3 6v2h18V6H3zm3 7h12v-2H6v2z" />
> </symbol>
>
> </defs>
> </svg>
>
>
> <div id="swagger-ui">
> <div data-reactroot="" class="swagger-ui">
> <div>
> <div class="information-container wrapper">
> <section class="block col-12">
> <div class="info">
> <hgroup class="main">
> <h2 class="title">httpbin.org <http://httpbin.org>
> <small>
> <pre class="version">0.9.2</pre>
> </small>
> </h2>
> <pre class="base-url">[ Base URL: httpbin.org/
> <http://httpbin.org/> ]</pre>
> </hgroup>
> <div class="description">
> <div class="markdown">
> <p>A simple HTTP Request & Response
> Service.
> <br>
> <br>
> <b>Run locally: </b>
> <code>$ docker run -p 80:80
> kennethreitz/httpbin</code>
> </p>
> </div>
> </div>
> <div>
> <div>
> <a href="https://kennethreitz.org <https://
> kennethreitz.org>" target="_blank">the developer - Website</a>
> </div>
> <a href="mailto:me_at_kennethreitz.org
> <mailto:me_at_kennethreitz.org>">Send email to the developer</a>
> </div>
> </div>
> <!-- ADDS THE LOADER SPINNER -->
> <div class="loading-container">
> <div class="loading"></div>
> </div>
>
> </section>
> </div>
> </div>
> </div>
> </div>
>
>
> <div class='swagger-ui'>
> <div class="wrapper">
> <section class="clear">
> <span style="float: right;">
> [Powered by
> <a target="_blank" href="https://github.com/rochacbruno/
> flasgger <https://github.com/rochacbruno/flasgger>">Flasgger</a>]
> <br>
> </span>
> </section>
> </div>
> </div>
>
>
>
> <script src="/flasgger_static/swagger-ui-bundle.js"> </script>
> <script src="/flasgger_static/swagger-ui-standalone-preset.js"> </script>
> <script src='/flasgger_static/lib/jquery.min.js' type='text/javascript'></
> script>
> <script>
>
> window.onload = function () {
>
>
> fetch("/spec.json")
> .then(function (response) {
> response.json()
> .then(function (json) {
> var current_protocol =
> window.location.protocol.slice(0, -1);
> if (json.schemes[0] != current_protocol) {
> // Switches scheme to the current in use
> var other_protocol = json.schemes[0];
> json.schemes[0] = current_protocol;
> json.schemes[1] = other_protocol;
>
> }
> json.host = window.location.host; // sets the
> current host
>
> const ui = SwaggerUIBundle({
> spec: json,
> validatorUrl: null,
> dom_id: '#swagger-ui',
> deepLinking: true,
> jsonEditor: true,
> docExpansion: "none",
> apisSorter: "alpha",
> //operationsSorter: "alpha",
> presets: [
> SwaggerUIBundle.presets.apis,
> // yay ES6 modules ↘
> Array.isArray(SwaggerUIStandalonePreset) ?
> SwaggerUIStandalonePreset : SwaggerUIStandalonePreset.default
> ],
> plugins: [
> SwaggerUIBundle.plugins.DownloadUrl
> ],
>
> // layout: "StandaloneLayout" // uncomment to enable the green top
> header
> })
>
> window.ui = ui
>
> // uncomment to rename the top brand if layout is enabled
> // $(".topbar-wrapper .link span").replaceWith("<span>httpbin</span>");
> })
> })
> }
> </script> <div class='swagger-ui'>
> <div class="wrapper">
> <section class="block col-12 block-desktop col-12-desktop">
> <div>
>
> <h2>Other Utilities</h2>
>
> <ul>
> <li>
> <a href="/forms/post">HTML form</a> that posts to /
> post /forms/post</li>
> </ul>
>
> <br />
> <br />
> </div>
> </section>
> </div>
> </div>
> </body>
>
> </html>
> ┌──(relun㉿relunsec)-[~/Test]
> └─$
>
> improve it to └─$ curl https://httpbin.org <https://httpbin.org> --ftp-ssl-ccc-
> mode activea
> Warning: unrecognized ftp CCC method 'activea' choose from 'active' and
> 'passive', using default
> <!DOCTYPE html>
> <html lang="en">
>
> <head>
> <meta charset="UTF-8">
> <title>httpbin.org <http://httpbin.org></title>
> <link href="https://fonts.googleapis.com/css?family=Open+Sans:400,700|
> Source+Code+Pro:300,600|Titillium+Web:400,600,700 <https://fonts.googleapis.com/
> css?family=Open+Sans:400,700|Source+Code+Pro:300,600|Titillium+Web:400,600,700>"
> rel="stylesheet">
> <link rel="stylesheet" type="text/css" href="/flasgger_static/swagger-ui.css">
> <link rel="icon" type="image/png" href="/static/favicon.ico" sizes="64x64
> 32x32 16x16" />
> <style>
> html {
> box-sizing: border-box;
> overflow: -moz-scrollbars-vertical;
> overflow-y: scroll;
> }
>
> *,
> *:before,
> *:after {
> box-sizing: inherit;
> }
>
> body {
> margin: 0;
> background: #fafafa;
> }
> </style>
> </head>
>
> <body>
> <a href="https://github.com/requests/httpbin <https://github.com/requests/
> httpbin>" class="github-corner" aria-label="View source on Github">
> <svg width="80" height="80" viewBox="0 0 250 250" style="fill:#151513;
> color:#fff; position: absolute; top: 0; border: 0; right: 0;"
> aria-hidden="true">
> <path d="M0,0 L115,115 L130,115 L142,142 L250,250 L250,0 Z"></path>
> <path d="M128.3,109.0 C113.8,99.7 119.0,89.6 119.0,89.6 C122.0,82.7
> 120.5,78.6 120.5,78.6 C119.2,72.0 123.4,76.3 123.4,76.3 C127.3,80.9 125.5,87.3
> 125.5,87.3 C122.9,97.6 130.6,101.9 134.4,103.2"
> fill="currentColor" style="transform-origin: 130px 106px;"
> class="octo-arm"></path>
> <path d="M115.0,115.0 C114.9,115.1 118.7,116.5 119.8,115.4
> L133.7,101.6 C136.9,99.2 139.9,98.4 142.2,98.6 C133.8,88.0 127.5,74.4 143.8,58.0
> C148.5,53.4 154.0,51.2 159.7,51.0 C160.3,49.4 163.2,43.6 171.4,40.1 C171.4,40.1
> 176.1,42.5 178.8,56.2 C183.1,58.6 187.2,61.8 190.9,65.4 C194.5,69.0 197.7,73.2
> 200.1,77.6 C213.8,80.2 216.3,84.9 216.3,84.9 C212.7,93.1 206.9,96.0 205.4,96.6
> C205.1,102.4 203.0,107.8 198.3,112.5 C181.9,128.9 168.3,122.5 157.7,114.1
> C157.9,116.9 156.7,120.9 152.7,124.9 L141.0,136.5 C139.8,137.7 141.6,141.9
> 141.8,141.8 Z"
> fill="currentColor" class="octo-body"></path>
> </svg>
> </a>
> <svg xmlns="http://www.w3.org/2000/svg <http://www.w3.org/2000/svg>"
> xmlns:xlink="http://www.w3.org/1999/xlink <http://www.w3.org/1999/xlink>"
> style="position:absolute;width:0;height:0">
> <defs>
> <symbol viewBox="0 0 20 20" id="unlocked">
> <path d="M15.8 8H14V5.6C14 2.703 12.665 1 10 1 7.334 1 6 2.703
> 6 5.6V6h2v-.801C8 3.754 8.797 3 10 3c1.203 0 2 .754 2 2.199V8H4c-.553 0-1 .646-1
> 1.199V17c0 .549.428 1.139.951 1.307l1.197.387C5.672 18.861 6.55 19 7.1
> 19h5.8c.549 0 1.428-.139
> 1.951-.307l1.196-.387c.524-.167.953-.757.953-1.306V9.199C17 8.646 16.352 8 15.8
> 8z"></path>
> </symbol>
>
> <symbol viewBox="0 0 20 20" id="locked">
> <path d="M15.8 8H14V5.6C14 2.703 12.665 1 10 1 7.334 1 6 2.703
> 6 5.6V8H4c-.553 0-1 .646-1 1.199V17c0 .549.428 1.139.951 1.307l1.197.387C5.672
> 18.861 6.55 19 7.1 19h5.8c.549 0 1.428-.139
> 1.951-.307l1.196-.387c.524-.167.953-.757.953-1.306V9.199C17 8.646 16.352 8 15.8
> 8zM12 8H8V5.199C8 3.754 8.797 3 10 3c1.203 0 2 .754 2 2.199V8z"
> />
> </symbol>
>
> <symbol viewBox="0 0 20 20" id="close">
> <path d="M14.348 14.849c-.469.469-1.229.469-1.697 0L10
> 11.819l-2.651 3.029c-.469.469-1.229.469-1.697 0-.469-.469-.469-1.229
> 0-1.697l2.758-3.15-2.759-3.152c-.469-.469-.469-1.228 0-1.697.469-.469 1.228-.469
> 1.697 0L10 8.183l2.651-3.031c.469-.469 1.228-.469 1.697 0 .469.469.469 1.229 0
> 1.697l-2.758 3.152 2.758 3.15c.469.469.469 1.229 0 1.698z"
> />
> </symbol>
>
> <symbol viewBox="0 0 20 20" id="large-arrow">
> <path d="M13.25 10L6.109 2.58c-.268-.27-.268-.707
> 0-.979.268-.27.701-.27.969 0l7.83 7.908c.268.271.268.709 0 .979l-7.83
> 7.908c-.268.271-.701.27-.969 0-.268-.269-.268-.707 0-.979L13.25 10z"
> />
> </symbol>
>
> <symbol viewBox="0 0 20 20" id="large-arrow-down">
> <path d="M17.418 6.109c.272-.268.709-.268.979 0s.271.701
> 0 .969l-7.908 7.83c-.27.268-.707.268-.979 0l-7.908-7.83c-.27-.268-.27-.701
> 0-.969.271-.268.709-.268.979 0L10 13.25l7.418-7.141z"
> />
> </symbol>
>
>
> <symbol viewBox="0 0 24 24" id="jump-to">
> <path d="M19 7v4H5.83l3.58-3.59L8 6l-6 6 6 6 1.41-1.41L5.83
> 13H21V7z" />
> </symbol>
>
> <symbol viewBox="0 0 24 24" id="expand">
> <path d="M10 18h4v-2h-4v2zM3 6v2h18V6H3zm3 7h12v-2H6v2z" />
> </symbol>
>
> </defs>
> </svg>
>
>
> <div id="swagger-ui">
> <div data-reactroot="" class="swagger-ui">
> <div>
> <div class="information-container wrapper">
> <section class="block col-12">
> <div class="info">
> <hgroup class="main">
> <h2 class="title">httpbin.org <http://httpbin.org>
> <small>
> <pre class="version">0.9.2</pre>
> </small>
> </h2>
> <pre class="base-url">[ Base URL: httpbin.org/
> <http://httpbin.org/> ]</pre>
> </hgroup>
> <div class="description">
> <div class="markdown">
> <p>A simple HTTP Request & Response
> Service.
> <br>
> <br>
> <b>Run locally: </b>
> <code>$ docker run -p 80:80
> kennethreitz/httpbin</code>
> </p>
> </div>
> </div>
> <div>
> <div>
> <a href="https://kennethreitz.org <https://
> kennethreitz.org>" target="_blank">the developer - Website</a>
> </div>
> <a href="mailto:me_at_kennethreitz.org
> <mailto:me_at_kennethreitz.org>">Send email to the developer</a>
> </div>
> </div>
> <!-- ADDS THE LOADER SPINNER -->
> <div class="loading-container">
> <div class="loading"></div>
> </div>
>
> </section>
> </div>
> </div>
> </div>
> </div>
>
>
> <div class='swagger-ui'>
> <div class="wrapper">
> <section class="clear">
> <span style="float: right;">
> [Powered by
> <a target="_blank" href="https://github.com/rochacbruno/
> flasgger <https://github.com/rochacbruno/flasgger>">Flasgger</a>]
> <br>
> </span>
> </section>
> </div>
> </div>
>
>
>
> <script src="/flasgger_static/swagger-ui-bundle.js"> </script>
> <script src="/flasgger_static/swagger-ui-standalone-preset.js"> </script>
> <script src='/flasgger_static/lib/jquery.min.js' type='text/javascript'></
> script>
> <script>
>
> window.onload = function () {
>
>
> fetch("/spec.json")
> .then(function (response) {
> response.json()
> .then(function (json) {
> var current_protocol =
> window.location.protocol.slice(0, -1);
> if (json.schemes[0] != current_protocol) {
> // Switches scheme to the current in use
> var other_protocol = json.schemes[0];
> json.schemes[0] = current_protocol;
> json.schemes[1] = other_protocol;
>
> }
> json.host = window.location.host; // sets the
> current host
>
> const ui = SwaggerUIBundle({
> spec: json,
> validatorUrl: null,
> dom_id: '#swagger-ui',
> deepLinking: true,
> jsonEditor: true,
> docExpansion: "none",
> apisSorter: "alpha",
> //operationsSorter: "alpha",
> presets: [
> SwaggerUIBundle.presets.apis,
> // yay ES6 modules ↘
> Array.isArray(SwaggerUIStandalonePreset) ?
> SwaggerUIStandalonePreset : SwaggerUIStandalonePreset.default
> ],
> plugins: [
> SwaggerUIBundle.plugins.DownloadUrl
> ],
>
> // layout: "StandaloneLayout" // uncomment to enable the green top
> header
> })
>
> window.ui = ui
>
> // uncomment to rename the top brand if layout is enabled
> // $(".topbar-wrapper .link span").replaceWith("<span>httpbin</span>");
> })
> })
> }
> </script> <div class='swagger-ui'>
> <div class="wrapper">
> <section class="block col-12 block-desktop col-12-desktop">
> <div>
>
> <h2>Other Utilities</h2>
>
> <ul>
> <li>
> <a href="/forms/post">HTML form</a> that posts to /
> post /forms/post</li>
> </ul>
>
> <br />
> <br />
> </div>
> </section>
> </div>
> </div>
> </body>
>
> </html>
> ┌──(relun㉿relunsec)-[~/Test]
> └─$
>
> and also you can improve other error messages you can adjust if you would.
>
> Dear
>
> RelunSec
>
>
>
>
-- Unsubscribe: https://lists.haxx.se/mailman/listinfo/curl-users Etiquette: https://curl.se/mail/etiquette.htmlReceived on 2025-08-15