STRELAYSRV(1)                      Syncthing                     STRELAYSRV(1)



NNAAMMEE
       strelaysrv - Syncthing Relay Server

SSYYNNOOPPSSIISS
          strelaysrv [-debug] [-ext-address=<address>] [-global-rate=<bytes/s>] [-keys=<dir>] [-listen=<listen addr>]
                     [-message-timeout=<duration>] [-nat] [-nat-lease=<duration> [-nat-renewal=<duration>]
                     [-nat-timeout=<duration>] [-network-timeout=<duration>] [-per-session-rate=<bytes/s>]
                     [-ping-interval=<duration>] [-pools=<pool addresses>] [-protocol=<string>] [-provided-by=<string>]
                     [-status-srv=<listen addr>]

DDEESSCCRRIIPPTTIIOONN
       Syncthing  relies  on a network of community-contributed relay servers.
       Anyone can run a relay server, and it will automatically join the relay
       pool  and  be  available to Syncthing users. The current list of relays
       can be found at _h_t_t_p_s_:_/_/_r_e_l_a_y_s_._s_y_n_c_t_h_i_n_g_._n_e_t_/.

OOPPTTIIOONNSS
       --ddeebbuugg Enable debug output.

       --eexxtt--aaddddrreessss==<<aaddddrreessss>>
              An optional address to advertising as being available on. Allows
              listening on an unprivileged port with port forwarding from e.g.
              443, and be connected to on port 443.

       --gglloobbaall--rraattee==<<bbyytteess//ss>>
              Global rate limit, in bytes/s.

       --kkeeyyss==<<ddiirr>>
              Directory where cert.pem and key.pem is stored (default â.â).

       --lliisstteenn==<<lliisstteenn aaddddrr>>
              Protocol listen address (default â:22067â).

       --mmeessssaaggee--ttiimmeeoouutt==<<dduurraattiioonn>>
              Maximum amount of time we wait for relevant messages  to  arrive
              (default 1m0s).

       --nnaatt   Use UPnP/NAT-PMP to acquire external port mapping

       --nnaatt--lleeaassee==<<dduurraattiioonn>>
              NAT lease length in minutes (default 60)

       --nnaatt--rreenneewwaall==<<dduurraattiioonn>>
              NAT renewal frequency in minutes (default 30)

       --nnaatt--ttiimmeeoouutt==<<dduurraattiioonn>>
              NAT discovery timeout in seconds (default 10)

       --nneettwwoorrkk--ttiimmeeoouutt==<<dduurraattiioonn>>
              Timeout for network operations between the client and the relay.
              If no data is received between the client and the relay in  this
              period of time, the connection is terminated. Furthermore, if no
              data is sent between either clients being  relayed  within  this
              period of time, the session is also terminated. (default 2m0s)

       --ppeerr--sseessssiioonn--rraattee==<<bbyytteess//ss>>
              Per session rate limit, in bytes/s.

       --ppiinngg--iinntteerrvvaall==<<dduurraattiioonn>>
              How often pings are sent (default 1m0s).

       --ppoooollss==<<ppooooll aaddddrreesssseess>>
              Comma separated list of relay pool addresses to join (default â‐
              _h_t_t_p_s_:_/_/_r_e_l_a_y_s_._s_y_n_c_t_h_i_n_g_._n_e_t_/_e_n_d_p_o_i_n_tâ).   Blank   to    disable
              announcement to a pool, thereby remaining a private relay.

       --pprroottooccooll==<<ssttrriinngg>>
              Protocol used for listening. âtcpâ for IPv4 and IPv6, âtcp4â for
              IPv4, âtcp6â for IPv6 (default âtcpâ).

       --pprroovviiddeedd--bbyy==<<ssttrriinngg>>
              An optional description about who provides the relay.

       --ssttaattuuss--ssrrvv==<<lliisstteenn aaddddrr>>
              Listen address for status service (blank  to  disable)  (default
              â:22070â).   Status  service is used by the relay pool server UI
              for displaying stats (data transferred, number of clients, etc.)

   IInnssttaalllliinngg
       Go  to  _r_e_l_e_a_s_e_s  <hhttttppss::////ggiitthhuubb..ccoomm//ssyynncctthhiinngg//rreellaayyssrrvv//rreelleeaasseess>  and
       download  the  file appropriate for your operating system. Unpacking it
       will yield a binary called ssttrreellaayyssrrvv (or ssttrreellaayyssrrvv..eexxee  on  Windows).
       Start this in whatever way you are most comfortable with; double click‐
       ing should work in any graphical environment.  At  first  start,  stre‐
       laysrv  will  generate  certificate  files  and database in the current
       directory unless given flags to the contrary. It  will  also  join  the
       default  pools  of  relays, which means that it is publicly visible and
       any client can connect to it.  The startup message prints  instructions
       on how to change this.

       The  relay  server  can also be obtained through apt, the Debian/Ubuntu
       package manager. Recent releases can be found at syncthingâs _a_p_t _r_e_p_o_s_‐
       _i_t_o_r_y  <hhttttppss::////aapptt..ssyynncctthhiinngg..nneett//>.  The  name of the package is sync‐
       thing-relaysrv.

SSEETTTTIINNGG UUPP
       Primarily, you need to decide on a directory to store the TLS  key  and
       certificate  and a listen port. The default listen port of 22067 works,
       but for optimal compatibility a well known port for  encrypted  traffic
       such  as  443 is recommended. This may require additional setup to work
       without running as root or a privileged user, see _R_u_n_n_i_n_g _o_n  _p_o_r_t  _4_4_3
       _a_s  _a_n  _u_n_p_r_i_v_i_l_e_g_e_d _u_s_e_r below. In principle something similar to this
       should work on a Linux/Unix system:

          $ sudo useradd strelaysrv
          $ sudo mkdir /etc/strelaysrv
          $ sudo chown strelaysrv /etc/strelaysrv
          $ sudo -u strelaysrv /usr/local/bin/strelaysrv -keys /etc/strelaysrv

       This creates a user ssttrreellaayyssrrvv and a directory //eettcc//ssttrreellaayyssrrvv to store
       the  keys. The keys are generated on first startup. The relay will join
       the global relay pool, unless a --ppoooollss=="""" argument is given.

       To make the relay server start automatically at boot,  use  the  recom‐
       mended procedure for your operating system.

   CClliieenntt ccoonnffiigguurraattiioonn
       Syncthing  can be configured to use specific relay servers (exclusively
       of the public pool) by adding the required servers to the Sync Protocol
       Listen Address field, under Actions and Settings. The format is as fol‐
       lows:
          relay://<host name|IP>[:port]/?id=<relay device ID>

       For example:
          relay://private-relay-1.exam‐
          ple.com:443/?id=ITZRNXE-YNROGBZ-HXTH5P7-VK5NYE5-QHRQGE2-7JQ6VNJ-KZUEDIU-5PPR5AM

       The relayâs device ID is output on start-up.

   RRuunnnniinngg oonn ppoorrtt 444433 aass aann uunnpprriivviilleeggeedd uusseerr
       It is recommended that you run the relay on port 443 (or  another  port
       which  is  commonly  allowed  through corporate firewalls), in order to
       maximise the chances that people are able to connect. However,  binding
       to  ports  below  1024 requires root privileges, and running a relay as
       root is not recommended. Thankfully there are a  couple  of  approaches
       available to you.

       One  option is to run the relay on port 22067, and use an iippttaabblleess rule
       to forward traffic from port 443 to port 22067, for example:

          iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 443 -j REDIRECT --to-port 22067

       Or, if youâre using uuffww, add the following to //eettcc//uuffww//bbeeffoorree..rruulleess:

          *nat
          :PREROUTING ACCEPT [0:0]
          :POSTROUTING ACCEPT [0:0]

          -A PREROUTING -i eth0 -p tcp --dport 443 -j REDIRECT --to-port 22067

          COMMIT

       You will need to start ssttrreellaayyssrrvv with --eexxtt--aaddddrreessss ""::444433"". This  tells
       ssttrreellaayyssrrvv that it can be contacted on port 443, even though it is lis‐
       tening on port 22067. You will also need to let both port 443 and 22067
       through your firewall.

       Another  option  is  _d_e_s_c_r_i_b_e_d _h_e_r_e <hhttttppss::////wwiikkii..aappaacchhee..oorrgg//hhttttppdd//NNoonn‐‐
       RRoooottPPoorrttBBiinnddiinngg>, although your mileage may vary.

FFIIRREEWWAALLLL CCOONNSSIIDDEERRAATTIIOONNSS
       The relay server listens on two ports by default.  One for data connec‐
       tions    and   the   other   for   providing   public   statistics   at
       _h_t_t_p_s_:_/_/_r_e_l_a_y_s_._s_y_n_c_t_h_i_n_g_._n_e_t_/.  The firewall, such  as  iippttaabblleess,  must
       permit incoming TCP connections to the following ports:

       · Data  port:   2222006677//ttccpp  overridden  with --lliisstteenn and advertised with
         --eexxtt--aaddddrreessss

       · Status port: 2222007700//ttccpp overridden with --ssttaattuuss--ssrrvv

       Runtime iippttaabblleess rules to allow access to the default ports:

          iptables -I INPUT -p tcp --dport 22067 -j ACCEPT
          iptables -I INPUT -p tcp --dport 22070 -j ACCEPT

       Please consult Linux distribution  documentation  to  persist  firewall
       rules.

SSEEEE AALLSSOO
       ssyynncctthhiinngg--rreellaayy((77)), ssyynncctthhiinngg--ffaaqq((77)), ssyynncctthhiinngg--nneettwwoorrkkiinngg((77))

AAUUTTHHOORR
       The Syncthing Authors

CCOOPPYYRRIIGGHHTT
       2014-2019, The Syncthing Authors



v1.19.2                          Apr 05, 2022                    STRELAYSRV(1)
