Curl hostname verification. > > The certificate subjects are: DNS:*.

Curl hostname verification Linux curl from WSL environment on same machine successfully connects to service via IP The check that the host name in the certificate is valid for the hostname you are connecting to is done independently of the CURLOPT_SSL_VERIFYPEER option. This is normal and expected. The hostname is taken from the subject or SAN entries of your certificate. In path to certificate . c explained The main compile-time defines to keep in mind when reading the host*. Oct 16, 2025 · Curl ignore invalid and self signed ssl certificate: Explains how to force curl command to ignore SSL certification warning for domain/IP Server Name Indication (SNI) is an extension to the Transport Layer Security (TLS) protocol that allows a client to specify the hostname it is trying to connect to at the start of the handshaking process. One of those backends is powered by the c-ares library and when curl is built to use c-ares, it gets a few extra superpowers that curl built to use other name resolve backends do not get. If --proto-default is provided several times, the last set value is used. Otherwise you can turn off cURL's verification of the certificate, use the -k (or --insecure) option. 36. You’ll learn when to use --resolve vs --connect-to, how to handle IPv6 and nonstandard ports, and get copy-paste examples If you truly want to disable curl SSL verification, by default, for ALL use cases, you can do as suggested in this Unix stack exchange answer: $ echo insecure >> ~/. com Without this option set, curl guesses protocol based on the hostname, see --url for details. se Jul 7, 2025 · Learn what curl -k does, when it’s safe to ignore SSL certificate errors, and why skipping verification in production environments is a security risk. In this case, the server you need to target is named “ host-server1. May 17, 2011 · Is there a way for the standard java SSL sockets to disable hostname verfication for ssl connections with a property? The only way I found until now, is to write a hostname verifier which returns t Jul 31, 2024 · This command ensures that cURL uses the correct hostname for SSL verification. Without this option set, curl guesses protocol based on the hostname, see --url for details. 58. c source file are these: CURLRES_IPV6 this host has getaddrinfo() and family, and thus we use that. illegal cert name field c. se Name resolve tricks with c-ares As should be detailed elsewhere in this book, curl may be built with several different name resolving backends. Practical solutions for common SSL issues when making secure API requests. 0 and onwards no longer sends a TLS close_notify on some scenarios, it just closes the TCP socket, such as host name verification failure (https://curl. 2 operating system iOS 14, configured with: Oct 4, 2024 · Originally posted by elvinasp October 3, 2024 Hello, I was making some networking labs and one of the examples was to connect via curl using various hosntname combinations and seeing how SNI behaves. In curl version 7. c Curl_verify_host calls cert_name_getstring which gathers the names. The certificate was downloaded by accessing the same server, by IP, with Firefox. 0, it doesn't, and the manpage says it doesn't: It does NOT affect the hostname/port that is used for TLS/SSL (e. curlrc settings in this guide for secure connections. This will allow cURL to run without verifying the certificate's validity, which can be beneficial during local testing or when connecting to servers with self-signed certificates. se] on behalf of Vadim > Grinshpun [vgrinshp_at_akamai. If you built your libcurl to target Windows 7 then it manually collects dnsnames CERT_ALT_NAME_DNS_NAME so IP addresses are skipped. SNI, certificate verification). > > www. Automation Scripts If you are using cURL in scripts (e. It helps users to transfer data across different network types, interacting directly with servers to download files, submit requests, and inspect web resources. enterprise-g1. This is deprecated, but as far as I can tell still expected to work. If I trusted the certificate in my Mac's Keychain, then everything worked accessing it by IP and without validating the certificate in cURL. 2 to check the existence of a common name and also verify that it matches Apr 12, 2025 · The Importance of Security While the CURL Ignore feature is a powerful tool, it is crucial to understand the implications of ignoring SSL verification. The Mar 17, 2025 · Learn how to ignore SSL certificate errors using cURL. 3 and curl >= 7. Oct 3, 2024 · If a CA certificate bundle is provided and Schannel is the backend then curl does the hostname verification instead of Schannel. www. com ” You could resolve the hostname before curl is used and use --resolve as shown before Mar 8, 2022 · I have an HTTPS server where the hostname is only in subject CN of the certificate, not in the SAN list. 0 approaches. > > The certificate subjects are: DNS:*. The code is beginning to see widespread testing as the release of OpenSSL 1. With its rich feature set and versatility, curl is May 6, 2015 · After adding curl_easy_setopt (curl, CURLOPT_VERBOSE, 1); to my code I find out that the problem was in certificate path. Apr 14, 2025 · CURL v8. com is a CNAME for > civiccms01live. May 30, 2024 · Learn how to bypass SSL certificate verification using -k or --insecure flags with examples. You shouldn't use this option because it allows man-in-the-middle attacks and defeats the To fix the “ curl: (6) Could not resolve host ” error, users can try multiple ways, check the spelling and validity of the hostname or IP address, use a different DNS server, or flush the DNS cache on the machine, check the network connection and firewall settings and make sure they allow curl to access the host. com] > Subject: can either libcurl's SSL/TLS hostname verification, or hostname > resolving, be overridden? > > With this scenario in mind, here are my questions: > (1) is there a (reasonably easy) way of tweaking what curl uses for > verifying the hostname during the SSL/TLS What does the --resolve option do in Curl? The --resolve option in curl is a powerful feature that allows you to manually specify hostname-to-IP address mappings, effectively bypassing DNS resolution for specific hosts. In the above snippet cURL uses 127. You must get cURL to access the correct domain-name for the certificate to work, and the way to map a certain domain to an IP is either by DNS or by the hosts-file. com ” and serves “ example. The host may not be able to resolve IPv6, but we do not really have to take that into account. This option allows curl to proceed and operate even for server connections otherwise considered insecure. . 0 libcurl is used by many applications, but not always advertised as such! SOLUTION libcurl 7. certificate subject name '%s' does not match target host name '%s' We need to distinguish these four cases from CURLE_PEER_FAILED_VERIFICATION. org> Date: Wed, 17 Jun 2020 10:45:34 -0400 cURL does not appear to be verifying that the hostname (subject/SAN) in a server certificate matches the requested host. com via DNS. curl is used daily by TLS options At the time of writing this, there are no less than forty different options for curl_easy_setopt that are dedicated for controlling how libcurl does SSL and TLS. CURLUE_BAD_LOGIN (23) The login part of the URL contained bad or invalid characters. Your data will continue to be It usually happens when the certificate does not match with the host name. Affected versions: from curl 7. Oct 2, 2025 · When you need to test a load balancer, CDN, or name-based virtual host, you often have to hit a specific IP while sending the real Host header. Also look at CURLOPT_SSL_VERIFYHOST: 1 to check the existence of a common name in the SSL peer certificate. If your services run behind an API gateway like AI Gateway or nginx, and you encounter Apr 28, 2018 · Hostname validation OpenSSL 1. 72. Oct 31, 2012 · I honestly don't think there's another way. haxx. southboroughtown. com See also --proto and --proto-redir. example. 0 has an improved hostname verification function that rejects wildcard matching against IP addresses. Example: curl --proto-default https ftp. Jul 18, 2023 · I’ve been using hostname spoofing with curl for a while and I find out why hostname spoofing doesn’t work with TLS. SSL encryption is designed to protect sensitive data during transmission. acquia-sites. Jan 10, 2025 · To ignore SSL certificate verification issues in cURL, you can use the -k or --insecure option. Resolving hostnames Aka hostip. > cURL does not appear to be verifying that the hostname (subject/SAN) in > a server certificate matches the requested host. com. You can use the -k flag with curl that will disable verification of the server's certificate or, even better a This option allows curl to proceed and operate even for server connections otherwise considered insecure. But this may create errors and problems in some cases. Jun 29, 2016 · The --resolve switch allows you to tell curl which address to request when it would resolve a given hostname. Oct 23, 2018 · a. no alternative certificate subject name matches target host name '%s' b. By ignoring SSL verification, you are potentially exposing yourself to security risks, such as man-in-the-middle attacks. So we want to fix this by extending the api. Using a newly built 7. pem, verifying the certificates and without getting as response something like: curl: (60) SSL: no alternative certificate subject name matches target host name '127. Dec 19, 2020 · I expected the following For curl to connect to the server, and ignore any and all potential SSL verification errors curl/libcurl version tiny-curl 7. Disabling verification makes the communication insecure. / should be added, otherwise libcurl can not find the certificate. This guide shows the right way to do it with curl—for both HTTP and HTTPS—so SNI and certificate validation stay intact. The Mar 16, 2025 · Without this option set, curl guesses protocol based on the hostname, see --url for details. Explore CURL parameters and . 1. CURLUE_BAD_IPV6 (22) The IPv6 address hostname contained bad or invalid characters. Viktor Dukhovni provided the implementation in January, 2015. Its been available in Master since that time. CURLUE_BAD Dec 5, 2023 · How to ignore SSL certificate errors using Curl? To bypass SSL certificate validation for local and test servers, you can pass the -k or --insecure option to the Curl command. I am getting the following error using curl: curl: (77) error setting certificate verify locations: CAfile: /etc/ssl/certs/ca-certificates. CURLRES_ARES is defined if According to documentation: to verify host or peer certificate you need to specify alternate certificates with the CURLOPT_CAINFO option or a certificate directory can be specified with the CURLOPT_CAPATH option. 1 (localhost) instead of resolving www. Conclusion In 2024, the art of SSL-free browsing Dec 19, 2024 · How to Use cURL to Ignore SSL Verification Errors In the world of web development and API integration, working with cURL often raises two common concerns: access management and the handling of SSL certificates. curl is also libcurl, used in cars, television sets, routers, printers, audio equipment, mobile phones, tablets, medical devices, settop boxes, computer games, media players and is the Internet transfer engine for countless software applications in over twenty billion installations. , for quick testing) where Jan 31, 2024 · How to bypass SSL certificate verification in cURL for HTTPS endpoints, addressing both direct requests and those via proxies. Curl will ignore any security warnings about an invalid SSL certificate and accept it as valid. # ifdef SKIP_HOSTNAME_VERIFICATION curl_easy_setopt (curl, CURLOPT_SSL_VERIFYHOST, 0L); # endif /* Note that this option is not strictly required, omitting it results in Jun 17, 2020 · From: Timothe Litt <litt_at_acm. unable to obtain common name from peer certificate d. It should. Disabling hostname validation can expose your application to security risks, such as man-in-the-middle attacks, where an attacker can impersonate the server you’re trying to connect to. Hosts that are not IPv6-enabled have CURLRES_IPV4 defined. 0. com is a CNAME for civiccms01live. > > In the following, the host is misconfigured (and may be fixed by the > time you see this). curlrc` file Dec 17, 2024 · The curl command-line tool is an essential utility for network interaction and data transfer, catering to a variety of communication protocols including HTTP, HTTPS, FTP, and more. curlrc Without this option set, curl guesses protocol based on the hostname, see --url for details. In schannel_verify. This option explicitly tells Curl to perform "insecure" SSL connections and file transfers. Jun 18, 2025 · Learn what SSL verification is, why it’s critical for secure connections, and how to enable or troubleshoot it in your apps, servers, and browsers. Jan 26, 2025 · Use Cases for cURL Ignoring SSL Certificate Validation Ignoring SSL certificate validation can come in handy in several real-world scenarios: Testing Local Services When you are developing an API locally with a self-signed certificate, you can use cURL with the -k option to test calls without hassle. 82. --proto-redir <protocols> Limit what protocols to allow on redirects. CURLUE_BAD_HOSTNAME (21) The hostname contained bad or invalid characters. In my case I was accessing the server by IP. g. Self-Signed Certificates: For testing environments using self-signed certificates, use the --cacert option with the certificate file: Jan 27, 2020 · Ignore SSL warnings in curl Sometimes your testing scenario or cycle is so far ahead of your infrastructure that you don&rsquo;t even have time or opportunity … Learn how to fix SSL certificate verification errors in cURL commands. But when I removed that certificate from Keychain and tried to validate it in cURL, I kept getting "verification failed" errors Learn how to use Curl with SSL certificates for secure web scraping. Pass a long set to 2L as asking curl to verify the DoH (DNS-over-HTTPS) server's certificate name fields against the hostname. By checking the server domain name with the certificate and validating the certificate via the CA (Certificate Authority). > From: curl-library [curl-library-bounces_at_cool. When I connected to demo server IP address using windows build-in curl, it failed to validate certificate. Also see how this could be handled both in the terminal and system-wide via the `. 3 to and including 7. 0 provides built-in functionality for hostname checking and validation. 10. 9. This allows for enforcing the validity of the remote HTTPS server SSL/TLS certificate. WARNING: disabling verification of the certificate allows bad guys to man-in-the-middle the communication without you knowing it. Jun 8, 2023 · Connect to hostname by specific host If you have a hostname that resolves to multiple front-end servers for the same site or service, you may want to issue a curl command to one specific server. Jun 9, 2024 · Thus a curl command with the https://hostname/ is required to set hostname as the SNI value and if OP then needs to do some fancy resolving using --resolve due to their internal shenanigans, well, that's just that Dec 31, 2020 · Ignore SSL/TLS Certificate Check By default, curl checks the SSL/TLS certificates for every HTTPS connection to make it secure. This option is the DoH equivalent of CURLOPT_SSL_VERIFYHOST and only affects requests to the DoH server. You are using a certificate that you have generated yourself signed by a Certificate Authority that you have also generated youself and curl is by default using your OS truststore, that obviously knows nothing about this custom Certificate Authority. The server connection is verified by making sure the server's certificate contains the right name and verifies successfully using the cert store. What is curl used for? curl is used in command lines or scripts to transfer data. Please note that as the option said, it is insecure. 35. 0 Not affected versions: curl < 7. This option is invaluable for testing, development, debugging, and scenarios where you need to override DNS settings without modifying system-wide configuration files. 0 and the public server certificate placed in /tmp/curltest/cacerts I see this: $ /tmp/curltest/curl Nov 10, 2017 · This can be because you have specified the wrong port number, entered the wrong host name, the wrong protocol or perhaps because there is a firewall or another network equipment in between that blocks the traffic from getting through. CURLUE_BAD_PASSWORD (24) The password part of the URL contained bad or invalid characters. Transfers done using TLS use safe defaults but since curl is used in many different scenarios and setups, chances are you end up in situations where you want to change those behaviors. See full list on curl. crt CApath: none How do I Oct 8, 2020 · Hi there! SHORT QUESTION: How can I make a curl request to a local ES cluster (3 nodes running on localhost) in the form of curl -XGET "https://localhost:9200" -u elastic --cacert elasticsearch-ca. How With enforce_hostname_verification enabled, the Security plugin verifies that the hostname of the communication partner matches the hostname in the certificate. In the following, the host is misconfigured (and may be fixed by the time you see this). 1' ? LONG VERSION: I set up a Apr 26, 2025 · PHP (PHP/cURL) In PHP, using the cURL extension, you can disable SSL certificate verification by setting the `CURLOPT_SSL_VERIFYPEER` option to false: Oct 17, 2025 · Enable verbose logging in curl command To troubleshoot the curl: (60) SSL certificate problem, it’s a good idea to enable verbose logging in curl. Verbose logging provides more details about the request and response, which can help identify the cause of the problem. Complete guide with client certificates, CA bundles, and troubleshooting tips. The solution would be to contact the host and ask it to fix its certificate. Follow this guide for a simple solution to bypass SSL checks while making secure requests. Protocol version With CURLOPT May 17, 2024 · Learn how to disable SSL verification in cURL with easy methods. ala vfeos dqqd uhn wilbkfw dklcm ruifwmx ddjiltu tnsz wnjpswl tnyzi liie qtkt jljijj jvfm