diff --git a/changelog.d/10443.doc b/changelog.d/10443.doc new file mode 100644 index 000000000..3588e5487 --- /dev/null +++ b/changelog.d/10443.doc @@ -0,0 +1 @@ +Add documentation for configuration a forward proxy. diff --git a/docs/SUMMARY.md b/docs/SUMMARY.md index 10be12d63..3d320a1c4 100644 --- a/docs/SUMMARY.md +++ b/docs/SUMMARY.md @@ -7,6 +7,7 @@ - [Installation](setup/installation.md) - [Using Postgres](postgres.md) - [Configuring a Reverse Proxy](reverse_proxy.md) + - [Configuring a Forward/Outbound Proxy](setup/forward_proxy.md) - [Configuring a Turn Server](turn-howto.md) - [Delegation](delegate.md) diff --git a/docs/setup/forward_proxy.md b/docs/setup/forward_proxy.md new file mode 100644 index 000000000..a0720ab34 --- /dev/null +++ b/docs/setup/forward_proxy.md @@ -0,0 +1,74 @@ +# Using a forward proxy with Synapse + +You can use Synapse with a forward or outbound proxy. An example of when +this is necessary is in corporate environments behind a DMZ (demilitarized zone). +Synapse supports routing outbound HTTP(S) requests via a proxy. Only HTTP(S) +proxy is supported, not SOCKS proxy or anything else. + +## Configure + +The `http_proxy`, `https_proxy`, `no_proxy` environment variables are used to +specify proxy settings. The environment variable is not case sensitive. +- `http_proxy`: Proxy server to use for HTTP requests. +- `https_proxy`: Proxy server to use for HTTPS requests. +- `no_proxy`: Comma-separated list of hosts, IP addresses, or IP ranges in CIDR + format which should not use the proxy. Synapse will directly connect to these hosts. + +The `http_proxy` and `https_proxy` environment variables have the form: `[scheme://][:@][:]` +- Supported schemes are `http://` and `https://`. The default scheme is `http://` + for compatibility reasons; it is recommended to set a scheme. If scheme is set + to `https://` the connection uses TLS between Synapse and the proxy. + + **NOTE**: Synapse validates the certificates. If the certificate is not + valid, then the connection is dropped. +- Default port if not given is `1080`. +- Username and password are optional and will be used to authenticate against + the proxy. + +**Examples** +- HTTP_PROXY=http://USERNAME:PASSWORD@10.0.1.1:8080/ +- HTTPS_PROXY=http://USERNAME:PASSWORD@proxy.example.com:8080/ +- NO_PROXY=master.hostname.example.com,10.1.0.0/16,172.30.0.0/16 + +**NOTE**: +Synapse does not apply the IP blacklist to connections through the proxy (since +the DNS resolution is done by the proxy). It is expected that the proxy or firewall +will apply blacklisting of IP addresses. + +## Connection types + +The proxy will be **used** for: + +- push +- url previews +- phone-home stats +- recaptcha validation +- CAS auth validation +- OpenID Connect +- Federation (checking public key revocation) + +It will **not be used** for: + +- Application Services +- Identity servers +- Outbound federation +- In worker configurations + - connections between workers + - connections from workers to Redis +- Fetching public keys of other servers +- Downloading remote media + +## Troubleshooting + +If a proxy server is used with TLS (HTTPS) and no connections are established, +it is most likely due to the proxy's certificates. To test this, the validation +in Synapse can be deactivated. + +**NOTE**: This has an impact on security and is for testing purposes only! + +To deactivate the certificate validation, the following setting must be made in +[homserver.yaml](../usage/configuration/homeserver_sample_config.md). + +```yaml +use_insecure_ssl_client_just_for_testing_do_not_use: true +```