CADDY-2.10.0 release notes and known issues

Summary

Caddy 2.10 is here! Aside from bug fixes, this release features: Encrypted ClientHello (ECH): This new technology encrypts the last plaintext portion of a TLS connection: the ClientHello, which includes the domain name being connected to. The draft spec for ECH is almost finalized, so we can now support this privacy feature for TLS. This is a powerful but nuanced capability; we highly recommend reading the ECH documentation on our website. Post-quantum (PQC) key exchange: Caddy now supports the standardized x25519mlkem768 cryptographic group by default. ACME profiles: ACME profiles are an experimental draft that allow you to choose properties of your certificates with more flexibility than traditional CSR methods. For example, Let's Encrypt will issue 6-day certificates under a certain profile. Caddy may eventually use that profile by default. Via header: The reverse proxy now sets a Via header instead of a duplicate Server header. Global DNS provider: You can now specify a default "global" DNS module to use instead of having to configure it locally in every part of your config that requires a DNS provider (for example, ACME DNS challenges, and ECH). This is the dns global option in the Caddyfile, or in JSON config, it's the dns parameter in the tls app configuration. Wildcards used by default: Previously, Caddy would obtain individual certificates for every domain in your config literally; now wildcards, if present, will be utilized for subdomains, rather than obtaining individual certificates. This change was motivated by the novel possibility for subdomain privacy afforded by ECH. It can be overridden with tls force_automate in the Caddyfile. The experimental auto_https prefer_wildcard option has been removed. libdns 1.0 APIs: Many of you use DNS provider modules to solve ACME DNS challenges or to enable dynamic DNS. They implement interfaces defined by libdns to get, set, append, and delete DNS records. After 5 years of production experience, including lessons learned with ECH, libdns APIs have been updated and 1.0 beta has been tagged. DNS provider packages will need to update their code to be compatible, which will help ensure stability and well-defined semantics for the future. Several packages have already updated or are in the process of updating (cloudflare, rfc2136, and desec to name a few). Global dns config: Now that several components of Caddy configuration may affect DNS records (ACME challenges, ECH publication, etc.), there is a new dns global option that can be used to specify your DNS provider config in a single place. This prevents repetition of credentials for servers where all the domains are managed by a single DNS provider. Thank you to the many contributors who have helped to make this possible! 🎉 🥳 🍾 ⚠️ While have traditionally supported the last 2 minor Go versions to accommodate some distribution / package manager policies, we now only support the latest minor Go version. The privacy and security benefits added in new Go versions (such as post-quantum cryptography) are worth making available to everyone as soon as possible, rather than holding back the entire user base or maintaining multiple code compilation configurations. Encrypted ClientHello (ECH) details (This is a brief overview. We recommend reading the full documentation .) Typically, server names (domain names, or "SNI") are sent in the plaintext ClientHello when establishing TLS connections. With ECH, the true server name is encrypted (and wrapped) by an "outer" ClientHello which has a generic SNI of your choosing. With many sites on the same server sharing the same outer SNI, both clients and the server have more privacy related to domain names. Caddy implements fully automated ECH, meaning that it generates (and soon , rotates), publishes, and serves ECH configurations simply by specifying a DNS provider, and the outer/public domain name to use. Fully automated ECH requires a DNS module built into your Caddy binary. In order for a clien

Improvements and security content

• Caddy 2.10 is here! Aside from bug fixes, this release features: Encrypted ClientHello (ECH): This new technology encrypts the last plaintext portion of a TLS connection: the ClientHello, which includes the domain name being connected to. The draft spec for ECH is almost finalized, so we can now support this privacy feature for TLS. This is a powerful but nuanced capability; we highly recommend reading the ECH documentation on our website. Post-quantum (PQC) key exchange: Caddy now supports the standardized x25519mlkem768 cryptographic group by default. ACME profiles: ACME profiles are an experimental draft that allow you to choose properties of your certificates with more flexibility than traditional CSR methods. For example, Let's Encrypt will issue 6-day certificates under a certain profile. Caddy may eventually use that profile by default. Via header: The reverse proxy now sets a Via header instead of a duplicate Server header. Global DNS provider: You can now specify a default "global" DNS module to use instead of having to configure it locally in every part of your config that requires a DNS provider (for example, ACME DNS challenges, and ECH). This is the dns global option in the Caddyfile, or in JSON config, it's the dns parameter in the tls app configuration. Wildcards used by default: Previously, Caddy would obtain individual certificates for every domain in your config literally; now wildcards, if present, will be utilized for subdomains, rather than obtaining individual certificates. This change was motivated by the novel possibility for subdomain privacy afforded by ECH. It can be overridden with tls force_automate in the Caddyfile. The experimental auto_https prefer_wildcard option has been removed. libdns 1.0 APIs: Many of you use DNS provider modules to solve ACME DNS challenges or to enable dynamic DNS. They implement interfaces defined by libdns to get, set, append, and delete DNS records. After 5 years of production experience, including lessons learned with ECH, libdns APIs have been updated and 1.0 beta has been tagged. DNS provider packages will need to update their code to be compatible, which will help ensure stability and well-defined semantics for the future. Several packages have already updated or are in the process of updating (cloudflare, rfc2136, and desec to name a few). Global dns config: Now that several components of Caddy configuration may affect DNS records (ACME challenges, ECH publication, etc.), there is a new dns global option that can be used to specify your DNS provider config in a single place. This prevents repetition of credentials for servers where all the domains are managed by a single DNS provider. Thank you to the many contributors who have helped to make this possible! 🎉 🥳 🍾 ⚠️ While have traditionally supported the last 2 minor Go versions to accommodate some distribution / package manager policies, we now only support the latest minor Go version. The privacy and security benefits added in new Go versions (such as post-quantum cryptography) are worth making available to everyone as soon as possible, rather than holding back the entire user base or maintaining multiple code compilation configurations. Encrypted ClientHello (ECH) details (This is a brief overview. We recommend reading the full documentation .) Typically, server names (domain names, or "SNI") are sent in the plaintext ClientHello when establishing TLS connections. With ECH, the true server name is encrypted (and wrapped) by an "outer" ClientHello which has a generic SNI of your choosing. With many sites on the same server sharing the same outer SNI, both clients and the server have more privacy related to domain names. Caddy implements fully automated ECH, meaning that it generates (and soon , rotates), publishes, and serves ECH configurations simply by specifying a DNS provider, and the outer/public domain name to use. Fully automated ECH requires a DNS module built into your Caddy binary. In order for a clien

Affected products and versions

Recommended action

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