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diff --git a/docs/MSC1711_certificates_FAQ.md b/docs/MSC1711_certificates_FAQ.md deleted file mode 100644 index 32ba15652d..0000000000 --- a/docs/MSC1711_certificates_FAQ.md +++ /dev/null @@ -1,314 +0,0 @@ -# MSC1711 Certificates FAQ - -## Historical Note -This document was originally written to guide server admins through the upgrade -path towards Synapse 1.0. Specifically, -[MSC1711](https://github.com/matrix-org/matrix-doc/blob/main/proposals/1711-x509-for-federation.md) -required that all servers present valid TLS certificates on their federation -API. Admins were encouraged to achieve compliance from version 0.99.0 (released -in February 2019) ahead of version 1.0 (released June 2019) enforcing the -certificate checks. - -Much of what follows is now outdated since most admins will have already -upgraded, however it may be of use to those with old installs returning to the -project. - -If you are setting up a server from scratch you almost certainly should look at -the [installation guide](setup/installation.md) instead. - -## Introduction -The goal of Synapse 0.99.0 is to act as a stepping stone to Synapse 1.0.0. It -supports the r0.1 release of the server to server specification, but is -compatible with both the legacy Matrix federation behaviour (pre-r0.1) as well -as post-r0.1 behaviour, in order to allow for a smooth upgrade across the -federation. - -The most important thing to know is that Synapse 1.0.0 will require a valid TLS -certificate on federation endpoints. Self signed certificates will not be -sufficient. - -Synapse 0.99.0 makes it easy to configure TLS certificates and will -interoperate with both >= 1.0.0 servers as well as existing servers yet to -upgrade. - -**It is critical that all admins upgrade to 0.99.0 and configure a valid TLS -certificate.** Admins will have 1 month to do so, after which 1.0.0 will be -released and those servers without a valid certificate will not longer be able -to federate with >= 1.0.0 servers. - -Full details on how to carry out this configuration change is given -[below](#configuring-certificates-for-compatibility-with-synapse-100). A -timeline and some frequently asked questions are also given below. - -For more details and context on the release of the r0.1 Server/Server API and -imminent Matrix 1.0 release, you can also see our -[main talk from FOSDEM 2019](https://matrix.org/blog/2019/02/04/matrix-at-fosdem-2019/). - -## Timeline - -**5th Feb 2019 - Synapse 0.99.0 is released.** - -All server admins are encouraged to upgrade. - -0.99.0: - -- provides support for ACME to make setting up Let's Encrypt certs easy, as - well as .well-known support. - -- does not enforce that a valid CA cert is present on the federation API, but - rather makes it easy to set one up. - -- provides support for .well-known - -Admins should upgrade and configure a valid CA cert. Homeservers that require a -.well-known entry (see below), should retain their SRV record and use it -alongside their .well-known record. - -**10th June 2019 - Synapse 1.0.0 is released** - -1.0.0 is scheduled for release on 10th June. In -accordance with the the [S2S spec](https://matrix.org/docs/spec/server_server/r0.1.0.html) -1.0.0 will enforce certificate validity. This means that any homeserver without a -valid certificate after this point will no longer be able to federate with -1.0.0 servers. - -## Configuring certificates for compatibility with Synapse 1.0.0 - -### If you do not currently have an SRV record - -In this case, your `server_name` points to the host where your Synapse is -running. There is no need to create a `.well-known` URI or an SRV record, but -you will need to give Synapse a valid, signed, certificate. - -### If you do have an SRV record currently - -If you are using an SRV record, your matrix domain (`server_name`) may not -point to the same host that your Synapse is running on (the 'target -domain'). (If it does, you can follow the recommendation above; otherwise, read -on.) - -Let's assume that your `server_name` is `example.com`, and your Synapse is -hosted at a target domain of `customer.example.net`. Currently you should have -an SRV record which looks like: - -``` -_matrix._tcp.example.com. IN SRV 10 5 8000 customer.example.net. -``` - -In this situation, you have three choices for how to proceed: - -#### Option 1: give Synapse a certificate for your matrix domain - -Synapse 1.0 will expect your server to present a TLS certificate for your -`server_name` (`example.com` in the above example). You can achieve this by acquiring a -certificate for the `server_name` yourself (for example, using `certbot`), and giving it -and the key to Synapse via `tls_certificate_path` and `tls_private_key_path`. - -#### Option 2: run Synapse behind a reverse proxy - -If you have an existing reverse proxy set up with correct TLS certificates for -your domain, you can simply route all traffic through the reverse proxy by -updating the SRV record appropriately (or removing it, if the proxy listens on -8448). - -See [the reverse proxy documentation](reverse_proxy.md) for information on setting up a -reverse proxy. - -#### Option 3: add a .well-known file to delegate your matrix traffic - -This will allow you to keep Synapse on a separate domain, without having to -give it a certificate for the matrix domain. - -You can do this with a `.well-known` file as follows: - - 1. Keep the SRV record in place - it is needed for backwards compatibility - with Synapse 0.34 and earlier. - - 2. Give Synapse a certificate corresponding to the target domain - (`customer.example.net` in the above example). You can do this by acquire a - certificate for the target domain and giving it to Synapse via `tls_certificate_path` - and `tls_private_key_path`. - - 3. Restart Synapse to ensure the new certificate is loaded. - - 4. Arrange for a `.well-known` file at - `https://<server_name>/.well-known/matrix/server` with contents: - - ```json - {"m.server": "<target server name>"} - ``` - - where the target server name is resolved as usual (i.e. SRV lookup, falling - back to talking to port 8448). - - In the above example, where synapse is listening on port 8000, - `https://example.com/.well-known/matrix/server` should have `m.server` set to one of: - - 1. `customer.example.net` ─ with a SRV record on - `_matrix._tcp.customer.example.com` pointing to port 8000, or: - - 2. `customer.example.net` ─ updating synapse to listen on the default port - 8448, or: - - 3. `customer.example.net:8000` ─ ensuring that if there is a reverse proxy - on `customer.example.net:8000` it correctly handles HTTP requests with - Host header set to `customer.example.net:8000`. - -## FAQ - -### Synapse 0.99.0 has just been released, what do I need to do right now? - -Upgrade as soon as you can in preparation for Synapse 1.0.0, and update your -TLS certificates as [above](#configuring-certificates-for-compatibility-with-synapse-100). - -### What will happen if I do not set up a valid federation certificate immediately? - -Nothing initially, but once 1.0.0 is in the wild it will not be possible to -federate with 1.0.0 servers. - -### What will happen if I do nothing at all? - -If the admin takes no action at all, and remains on a Synapse < 0.99.0 then the -homeserver will be unable to federate with those who have implemented -.well-known. Then, as above, once the month upgrade window has expired the -homeserver will not be able to federate with any Synapse >= 1.0.0 - -### When do I need a SRV record or .well-known URI? - -If your homeserver listens on the default federation port (8448), and your -`server_name` points to the host that your homeserver runs on, you do not need an -SRV record or `.well-known/matrix/server` URI. - -For instance, if you registered `example.com` and pointed its DNS A record at a -fresh Upcloud VPS or similar, you could install Synapse 0.99 on that host, -giving it a server_name of `example.com`, and it would automatically generate a -valid TLS certificate for you via Let's Encrypt and no SRV record or -`.well-known` URI would be needed. - -This is the common case, although you can add an SRV record or -`.well-known/matrix/server` URI for completeness if you wish. - -**However**, if your server does not listen on port 8448, or if your `server_name` -does not point to the host that your homeserver runs on, you will need to let -other servers know how to find it. - -In this case, you should see ["If you do have an SRV record -currently"](#if-you-do-have-an-srv-record-currently) above. - -### Can I still use an SRV record? - -Firstly, if you didn't need an SRV record before (because your server is -listening on port 8448 of your server_name), you certainly don't need one now: -the defaults are still the same. - -If you previously had an SRV record, you can keep using it provided you are -able to give Synapse a TLS certificate corresponding to your server name. For -example, suppose you had the following SRV record, which directs matrix traffic -for example.com to matrix.example.com:443: - -``` -_matrix._tcp.example.com. IN SRV 10 5 443 matrix.example.com -``` - -In this case, Synapse must be given a certificate for example.com - or be -configured to acquire one from Let's Encrypt. - -If you are unable to give Synapse a certificate for your server_name, you will -also need to use a .well-known URI instead. However, see also "I have created a -.well-known URI. Do I still need an SRV record?". - -### I have created a .well-known URI. Do I still need an SRV record? - -As of Synapse 0.99, Synapse will first check for the existence of a `.well-known` -URI and follow any delegation it suggests. It will only then check for the -existence of an SRV record. - -That means that the SRV record will often be redundant. However, you should -remember that there may still be older versions of Synapse in the federation -which do not understand `.well-known` URIs, so if you removed your SRV record you -would no longer be able to federate with them. - -It is therefore best to leave the SRV record in place for now. Synapse 0.34 and -earlier will follow the SRV record (and not care about the invalid -certificate). Synapse 0.99 and later will follow the .well-known URI, with the -correct certificate chain. - -### It used to work just fine, why are you breaking everything? - -We have always wanted Matrix servers to be as easy to set up as possible, and -so back when we started federation in 2014 we didn't want admins to have to go -through the cumbersome process of buying a valid TLS certificate to run a -server. This was before Let's Encrypt came along and made getting a free and -valid TLS certificate straightforward. So instead, we adopted a system based on -[Perspectives](https://en.wikipedia.org/wiki/Convergence_(SSL)): an approach -where you check a set of "notary servers" (in practice, homeservers) to vouch -for the validity of a certificate rather than having it signed by a CA. As long -as enough different notaries agree on the certificate's validity, then it is -trusted. - -However, in practice this has never worked properly. Most people only use the -default notary server (matrix.org), leading to inadvertent centralisation which -we want to eliminate. Meanwhile, we never implemented the full consensus -algorithm to query the servers participating in a room to determine consensus -on whether a given certificate is valid. This is fiddly to get right -(especially in face of sybil attacks), and we found ourselves questioning -whether it was worth the effort to finish the work and commit to maintaining a -secure certificate validation system as opposed to focusing on core Matrix -development. - -Meanwhile, Let's Encrypt came along in 2016, and put the final nail in the -coffin of the Perspectives project (which was already pretty dead). So, the -Spec Core Team decided that a better approach would be to mandate valid TLS -certificates for federation alongside the rest of the Web. More details can be -found in -[MSC1711](https://github.com/matrix-org/matrix-doc/blob/main/proposals/1711-x509-for-federation.md#background-the-failure-of-the-perspectives-approach). - -This results in a breaking change, which is disruptive, but absolutely critical -for the security model. However, the existence of Let's Encrypt as a trivial -way to replace the old self-signed certificates with valid CA-signed ones helps -smooth things over massively, especially as Synapse can now automate Let's -Encrypt certificate generation if needed. - -### Can I manage my own certificates rather than having Synapse renew certificates itself? - -Yes, you are welcome to manage your certificates yourself. Synapse will only -attempt to obtain certificates from Let's Encrypt if you configure it to do -so.The only requirement is that there is a valid TLS cert present for -federation end points. - -### Do you still recommend against using a reverse proxy on the federation port? - -We no longer actively recommend against using a reverse proxy. Many admins will -find it easier to direct federation traffic to a reverse proxy and manage their -own TLS certificates, and this is a supported configuration. - -See [the reverse proxy documentation](reverse_proxy.md) for information on setting up a -reverse proxy. - -### Do I still need to give my TLS certificates to Synapse if I am using a reverse proxy? - -Practically speaking, this is no longer necessary. - -If you are using a reverse proxy for all of your TLS traffic, then you can set -`no_tls: True`. In that case, the only reason Synapse needs the certificate is -to populate a legacy 'tls_fingerprints' field in the federation API. This is -ignored by Synapse 0.99.0 and later, and the only time pre-0.99 Synapses will -check it is when attempting to fetch the server keys - and generally this is -delegated via `matrix.org`, which is on 0.99.0. - -However, there is a bug in Synapse 0.99.0 -[4554](<https://github.com/matrix-org/synapse/issues/4554>) which prevents -Synapse from starting if you do not give it a TLS certificate. To work around -this, you can give it any TLS certificate at all. This will be fixed soon. - -### Do I need the same certificate for the client and federation port? - -No. There is nothing stopping you from using different certificates, -particularly if you are using a reverse proxy. However, Synapse will use the -same certificate on any ports where TLS is configured. - -### How do I tell Synapse to reload my keys/certificates after I replace them? - -Synapse will reload the keys and certificates when it receives a SIGHUP - for -example `kill -HUP $(cat homeserver.pid)`. Alternatively, simply restart -Synapse, though this will result in downtime while it restarts. |