495 lines
15 KiB
Groff
495 lines
15 KiB
Groff
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.in \\n[rst2man-indent\\n[rst2man-indent-level]]u
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..
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.TH "STDISCOSRV" "1" "Mar 21, 2024" "v1.27.4" "Syncthing"
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.SH NAME
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stdiscosrv \- Syncthing Discovery Server
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.SH SYNOPSIS
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.INDENT 0.0
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.INDENT 3.5
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.sp
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.nf
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.ft C
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stdiscosrv [\-cert=<file>] [\-db\-dir=<string>] [\-debug] [\-http] [\-key=<string>]
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[\-listen=<address>] [\-metrics\-listen=<address>]
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[\-replicate=<peers>] [\-replication\-listen=<address>]
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.ft P
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.fi
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.UNINDENT
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.UNINDENT
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.SH DESCRIPTION
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.sp
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Syncthing relies on a discovery server to find peers on the internet. Anyone
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can run a discovery server and point Syncthing installations to it. The
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Syncthing project also maintains a global cluster for public use.
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.SH OPTIONS
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.INDENT 0.0
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.TP
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.B \-cert=<file>
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Certificate file (default “./cert.pem”).
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.UNINDENT
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.INDENT 0.0
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.TP
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.B \-db\-dir=<string>
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Database directory, where data is stored (default “./discovery.db”).
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.UNINDENT
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.INDENT 0.0
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.TP
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.B \-debug
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Enable debug output.
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.UNINDENT
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.INDENT 0.0
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.TP
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.B \-http
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Listen on HTTP (behind an HTTPS proxy).
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.UNINDENT
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.INDENT 0.0
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.TP
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.B \-key=<file>
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Key file (default “./key.pem”).
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.UNINDENT
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.INDENT 0.0
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.TP
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.B \-listen=<address>
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Listen address (default “:8443”).
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.UNINDENT
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.INDENT 0.0
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.TP
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.B \-metrics\-listen=<address>
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Prometheus compatible metrics endpoint listen address (default disabled).
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.UNINDENT
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.INDENT 0.0
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.TP
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.B \-replicate=<peers>
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Replication peers, \fI\%id@address\fP <\fBid@address\fP>, comma separated
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.UNINDENT
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.INDENT 0.0
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.TP
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.B \-replication\-listen=<address>
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Listen address for incoming replication connections (default “:19200”).
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.UNINDENT
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.SH POINTING SYNCTHING AT YOUR DISCOVERY SERVER
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.sp
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By default, Syncthing uses a number of global discovery servers, signified by
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the entry \fBdefault\fP in the list of discovery servers. To make Syncthing use
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your own instance of stdiscosrv, open up Syncthing’s web GUI. Go to settings,
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Global Discovery Server and add stdiscosrv’s host address to the comma\-separated
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list, e.g. \fBhttps://disco.example.com:8443/\fP\&. Note that stdiscosrv uses port
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8443 by default. For stdiscosrv to be available over the internet with a dynamic
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IP address, you will need a dynamic DNS service.
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.sp
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Deprecated since version v0.14.44: Prior versions need \fB/v2/\fP appended to the discovery
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server address, e.g. \fBhttps://disco.example.com:8443/v2/\fP\&.
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.sp
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If you wish to use \fIonly\fP your own discovery server, remove the \fBdefault\fP
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entry from the list.
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.SH SETTING UP
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.SS Description
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.sp
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This guide assumes that you have already set up Syncthing. If you
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haven’t yet, head over to \fI\%Getting Started\fP first.
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.SS Installing
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.sp
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Go to \fI\%releases\fP <\fBhttps://github.com/syncthing/discosrv/releases\fP> and
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download the file appropriate for your operating system. Unpacking it will
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yield a binary called \fBstdiscosrv\fP (or \fBstdiscosrv.exe\fP on Windows).
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Start this in whatever way you are most comfortable with; double clicking
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should work in any graphical environment. At first start, stdiscosrv will
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generate certificate files and database in the current directory unless
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given flags to the contrary.
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.sp
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The discovery server can also be obtained through apt, the Debian/Ubuntu package
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manager. Recent releases can be found at syncthing’s
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\fI\%apt repository\fP <\fBhttps://apt.syncthing.net/\fP>\&. The name of the package is
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syncthing\-discosrv.
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.SS Configuring
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.sp
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\fBNOTE:\fP
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.INDENT 0.0
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.INDENT 3.5
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If you are running an instance of Syncthing on the discovery server,
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you must either add that instance to other devices using a static
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address or bind the discovery server and Syncthing instances to
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different IP addresses.
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.UNINDENT
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.UNINDENT
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.SS Certificates
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.sp
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The discovery server provides service over HTTPS. To ensure secure connections
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from clients there are three options:
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.INDENT 0.0
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.IP \(bu 2
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Use a CA\-signed certificate pair for the domain name you will use for the
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discovery server. This is like any other HTTPS website; clients will
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authenticate the server based on its certificate and domain name.
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.IP \(bu 2
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Use any certificate pair and let clients authenticate the server based on
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its “device ID” (similar to Syncthing\-to\-Syncthing authentication). This
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option can be used with the certificate automatically generated by the
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discovery server.
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.IP \(bu 2
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Pass the \fB\-http\fP flag if the discovery server is behind an SSL\-secured
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reverse proxy. See below for configuration.
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.UNINDENT
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.sp
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For the first two options, the discovery server must be given the paths to
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the certificate and key at startup. This isn’t necessary with the \fBhttp\fP flag:
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.INDENT 0.0
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.INDENT 3.5
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.sp
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.nf
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.ft C
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$ stdiscosrv \-cert=/path/to/cert.pem \-key=/path/to/key.pem
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Server device ID is 7DDRT7J\-UICR4PM\-PBIZYL3\-MZOJ7X7\-EX56JP6\-IK6HHMW\-S7EK32W\-G3EUPQA
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.ft P
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.fi
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.UNINDENT
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.UNINDENT
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.sp
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The discovery server prints its device ID at startup. In case you are using
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a non CA signed certificate, this device ID (fingerprint) must be given to
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the clients in the discovery server URL:
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.INDENT 0.0
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.INDENT 3.5
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.sp
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.nf
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.ft C
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https://disco.example.com:8443/?id=7DDRT7J\-UICR4PM\-PBIZYL3\-MZOJ7X7\-EX56JP6\-IK6HHMW\-S7EK32W\-G3EUPQA
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.ft P
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.fi
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.UNINDENT
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||
.UNINDENT
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.sp
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Otherwise, the URL will be:
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.INDENT 0.0
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.INDENT 3.5
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.sp
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.nf
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.ft C
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https://disco.example.com:8443/
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.ft P
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.fi
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.UNINDENT
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.UNINDENT
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.SS Replication
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.sp
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The discovery server can be deployed in a redundant, load sharing fashion.
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In this mode announcements are replicated from the server that receives them
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to other peer servers and queries can be answered equally by all servers.
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.sp
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Replication connections are encrypted and authenticated using TLS. The
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certificate is selected by the \fB\-cert\fP and \fB\-key\fP options and is thus
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shared with the main discovery API. If the \fB\-http\fP mode is used the
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certificate is not used for client requests but only for replication
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connections.
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.sp
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Authentication of replication connections is done using \fI\%Syncthing\-style
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device IDs\fP <\fBhttps://docs.syncthing.net/dev/device-ids.html#id1\fP> only \- CA
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verification is not available. The device IDs in question are those printed
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by the discovery server on startup.
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.sp
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Replication connections are unidirectional \- announcements are replication
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from the \fBsender\fP to a \fBlistener\fP\&. In order to have a bidirectional
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replication relationship between two servers both need to be configured as
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sender and listener.
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.sp
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As an example, lets assume two discovery servers:
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.INDENT 0.0
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.IP \(bu 2
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Server one is on 192.0.2.20 and has certificate ID I6K…H76
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.IP \(bu 2
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Server two is on 192.0.2.55 and has certificate ID MRI…7OK
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.UNINDENT
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.sp
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In order for both to replicate to the other and thus form a redundant pair,
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use the following commands.
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.sp
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On server one:
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.INDENT 0.0
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.INDENT 3.5
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.sp
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.nf
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.ft C
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$ stdiscosrv \-replicate=MRI...7OK@192.0.2.55:19200 <other options>
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.ft P
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.fi
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||
.UNINDENT
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||
.UNINDENT
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||
.sp
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||
On server two:
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||
.INDENT 0.0
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.INDENT 3.5
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||
.sp
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||
.nf
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||
.ft C
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||
$ stdiscosrv \-replicate=I6K...H76@192.0.2.20:19200 <other options>
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.ft P
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||
.fi
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||
.UNINDENT
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||
.UNINDENT
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||
.sp
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||
The \fB\-replicate\fP directive sets which remote device IDs are expected and
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allowed for both outgoing (sending) and incoming (listening) connections,
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and which addresses to use when connecting out to those peers. Both IP and
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port must be specified in peer addresses.
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.sp
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||
It is possible to only allow incoming connections from a peer without
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establishing an outgoing replication connection. To do so, give only the
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device ID without “@ip:port” address:
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||
.INDENT 0.0
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||
.INDENT 3.5
|
||
.sp
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||
.nf
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||
.ft C
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||
$ stdiscosrv \-replicate=I6K...H76 <other options>
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.ft P
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||
.fi
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||
.UNINDENT
|
||
.UNINDENT
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||
.sp
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Discosrv will listen on the replication port only when \fB\-replicate\fP is
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given. The default replication listen address is “:19200”.
|
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.sp
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||
To achieve load balancing over two mutually replicating discovery server
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instances, add multiple A / AAAA DNS records for a given name and point
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Syncthing towards this name. The same certificate must be used on both
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discovery servers.
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.SS Reverse Proxy Setup
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.sp
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New in version 1.8.0: A new “X\-Client\-Port” HTTP header was added.
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.sp
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The discovery server can be run behind an SSL\-secured reverse proxy. This
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allows:
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.INDENT 0.0
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.IP \(bu 2
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Use of a subdomain name without requiring a port number added to the URL
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.IP \(bu 2
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Sharing an SSL certificate with multiple services on the same server
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.UNINDENT
|
||
.sp
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||
Note that after this configuration, if the proxy uses a valid HTTPS
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||
certificate, \fBclients should omit the\fP \fB?id=...\fP \fBparameter from the
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discovery server URL on their configuration\fP\&. Client\-side validation will be
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||
done by checking the visible proxy server’s HTTPS certificate. If, however, the
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proxy uses a self\-signed or somehow invalid certificate, clients must still set
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the \fB?id=...\fP parameter with the computed hash of the proxy’s
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certificate. Using such setup is discouraged and is not covered in this page.
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Always favour using valid and widely recognised certificates.
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.SS Requirements
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.INDENT 0.0
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.IP \(bu 2
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Run the discovery server using the \-http flag: \fBstdiscosrv \-http\fP\&.
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.IP \(bu 2
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SSL certificate/key configured for the reverse proxy.
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.IP \(bu 2
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The “X\-Forwarded\-For” HTTP header must be passed through with the client’s
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real IP address.
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.IP \(bu 2
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The “X\-Client\-Port” HTTP header should be passed through, containing the client’s real connection port.
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.IP \(bu 2
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The “X\-SSL\-Cert” HTTP header must be passed through with the PEM\-encoded
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client SSL certificate. This will be present in POST requests and may be empty
|
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in GET requests from clients. If you see syncthing\-discosrv outputting
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\fBno certificates\fP when receiving POST requests, that’s because the proxy
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is not passing this header through.
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.IP \(bu 2
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The proxy must request the client SSL certificate but not require it to be
|
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signed by a trusted CA.
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.UNINDENT
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.SS Nginx
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.sp
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These lines in the configuration take care of the last four requirements
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listed above:
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.INDENT 0.0
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.INDENT 3.5
|
||
.sp
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||
.nf
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.ft C
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proxy_set_header X\-Forwarded\-For $proxy_add_x_forwarded_for;
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proxy_set_header X\-Client\-Port $remote_port;
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proxy_set_header X\-SSL\-Cert $ssl_client_cert;
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ssl_verify_client optional_no_ca;
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.ft P
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||
.fi
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.UNINDENT
|
||
.UNINDENT
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||
.sp
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||
The following is a complete example Nginx configuration file. With this setup,
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clients can use \fI\%https://discovery.example.com\fP as the discovery server URL in
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the Syncthing settings.
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.INDENT 0.0
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.INDENT 3.5
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.sp
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.nf
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.ft C
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# HTTP 1.1 support
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proxy_http_version 1.1;
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proxy_buffering off;
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proxy_set_header Host $http_host;
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proxy_set_header Upgrade $http_upgrade;
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proxy_set_header Connection $http_connection;
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proxy_set_header X\-Real\-IP $remote_addr;
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proxy_set_header X\-Client\-Port $remote_port;
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proxy_set_header X\-Forwarded\-For $proxy_add_x_forwarded_for;
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proxy_set_header X\-Forwarded\-Proto $http_x_forwarded_proto;
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proxy_set_header X\-SSL\-Cert $ssl_client_cert;
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upstream discovery.example.com {
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# Local IP address:port for discovery server
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server 192.0.2.1:8443;
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}
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server {
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server_name discovery.example.com;
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listen 80;
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access_log /var/log/nginx/access.log vhost;
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return 301 https://$host$request_uri;
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}
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server {
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server_name discovery.example.com;
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||
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listen 443 ssl http2;
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access_log /var/log/nginx/access.log vhost;
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|
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# Mozilla Intermediate configuration (https://wiki.mozilla.org/Security/Server_Side_TLS)
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ssl_protocols TLSv1.2 TLSv1.3;
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ssl_ciphers ECDHE\-ECDSA\-AES128\-GCM\-SHA256:ECDHE\-RSA\-AES128\-GCM\-SHA256:ECDHE\-ECDSA\-AES256\-GCM\-SHA384:ECDHE\-RSA\-AES256\-GCM\-SHA384:ECDHE\-ECDSA\-CHACHA20\-POLY1305:ECDHE\-RSA\-CHACHA20\-POLY1305:DHE\-RSA\-AES128\-GCM\-SHA256:DHE\-RSA\-AES256\-GCM\-SHA384;
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ssl_prefer_server_ciphers off;
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||
ssl_session_tickets off;
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ssl_session_timeout 5m;
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ssl_session_cache shared:SSL:50m;
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ssl_verify_client optional_no_ca;
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|
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# OCSP stapling
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||
ssl_stapling on;
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||
ssl_stapling_verify on;
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||
|
||
# Certificates
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||
ssl_certificate /etc/nginx/certs/discovery.example.com.crt;
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||
ssl_certificate_key /etc/nginx/certs/discovery.example.com.key;
|
||
|
||
# curl https://ssl\-config.mozilla.org/ffdhe2048.txt > /path/to/dhparam
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ssl_dhparam /path/to/dhparam;
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||
|
||
# HSTS (ngx_http_headers_module is required) (63072000 seconds)
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||
add_header Strict\-Transport\-Security \(dqmax\-age=63072000\(dq always;
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||
|
||
location / {
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||
proxy_pass http://discovery.example.com;
|
||
}
|
||
}
|
||
.ft P
|
||
.fi
|
||
.UNINDENT
|
||
.UNINDENT
|
||
.sp
|
||
An example of automating the SSL certificates and reverse\-proxying the Discovery
|
||
Server and Syncthing using Nginx, \fI\%Let’s Encrypt\fP <\fBhttps://letsencrypt.org/\fP> and Docker can be found \fI\%here\fP <\fBhttps://forum.syncthing.net/t/docker-syncthing-and-syncthing-discovery-behind-nginx-reverse-proxy-with-lets-encrypt/6880\fP>\&.
|
||
.SS Apache
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||
.sp
|
||
The following lines must be added to the configuration:
|
||
.INDENT 0.0
|
||
.INDENT 3.5
|
||
.sp
|
||
.nf
|
||
.ft C
|
||
SSLProxyEngine On
|
||
SSLVerifyClient optional_no_ca
|
||
RequestHeader set X\-SSL\-Cert \(dq%{SSL_CLIENT_CERT}s\(dq
|
||
.ft P
|
||
.fi
|
||
.UNINDENT
|
||
.UNINDENT
|
||
.sp
|
||
The following was observed to not be required at least under
|
||
Apache httpd 2.4.38, as the proxy module adds the needed header by default.
|
||
If you need to explicitly add the following directive, make sure to issue
|
||
\fBa2enmod remoteip\fP first. Then, add the following to your Apache httpd
|
||
configuration:
|
||
.INDENT 0.0
|
||
.INDENT 3.5
|
||
.sp
|
||
.nf
|
||
.ft C
|
||
RemoteIPHeader X\-Forwarded\-For
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||
.ft P
|
||
.fi
|
||
.UNINDENT
|
||
.UNINDENT
|
||
.SS Caddy
|
||
.sp
|
||
The following lines must be added to the Caddyfile:
|
||
.INDENT 0.0
|
||
.INDENT 3.5
|
||
.sp
|
||
.nf
|
||
.ft C
|
||
discovery.example.com {
|
||
reverse_proxy 192.0.2.1:8443 {
|
||
header_up X\-Forwarded\-For {http.request.remote.host}
|
||
header_up X\-Client\-Port {http.request.remote.port}
|
||
header_up X\-Tls\-Client\-Cert\-Der\-Base64 {http.request.tls.client.certificate_der_base64}
|
||
}
|
||
|
||
tls {
|
||
client_auth {
|
||
mode request
|
||
}
|
||
}
|
||
}
|
||
.ft P
|
||
.fi
|
||
.UNINDENT
|
||
.UNINDENT
|
||
.INDENT 0.0
|
||
.INDENT 3.5
|
||
.sp
|
||
.nf
|
||
.ft C
|
||
|
||
.ft P
|
||
.fi
|
||
.UNINDENT
|
||
.UNINDENT
|
||
.sp
|
||
For more details, see also the recommendations in the
|
||
\fI\%Reverse Proxy Setup\fP <\fBhttps://docs.syncthing.net/users/reverseproxy.html\fP>
|
||
page. Note that that page is directed at setting up a proxy for the
|
||
Syncthing web UI. You should do the proper path and port adjustments to proxying
|
||
the discovery server and your particular setup.
|
||
.SH SEE ALSO
|
||
.sp
|
||
\fBsyncthing\-networking(7)\fP, \fBsyncthing\-faq(7)\fP
|
||
.SH AUTHOR
|
||
The Syncthing Authors
|
||
.SH COPYRIGHT
|
||
2014-2019, The Syncthing Authors
|
||
.\" Generated by docutils manpage writer.
|
||
.
|