+++ title = "cozy ejabberd xmpp chat server" created_at = "2023-09-16T21:07:40+0100" tags = ["tech", "sysadmin"] +++ today we are going to do the **ultimate** *cozy* ejabberd server guide. the only prerequisites for this guide are, one, having already set up some form of server, whether it be a vps, or an old laptop behind your fridge, it doesn't matter, because this isn't the email network, and two, ownership of a domain name, e.g. `blos.sm`. we shall begin with a single virtualhost[^1]. for example purposes, we will use `example.slay` (let's imagine this is a real tld because why not) as the domain. just replace all instances of `example.slay` with your own domain. [^1]: virtualhosts allow more than one xmpp service to be run on one server. for example, you could have one xmpp service with the domain `example.slay` and another xmpp service with the domain `example.flop`, both somewhat separated from each other as if they were run on different servers.
checklist!: - [ ] add dns records - [ ] open firewall ports - [ ] set up web server - [ ] get ssl certificates - [ ] set up postgres database - [ ] install ejabberd - [ ] write configuration - [ ] start service
## step 1: set up your dns records you will need dns A/AAAA records and srv records for each service on your xmpp server. you will need a records for: - `example.slay` - `muc.example.slay` (for group chats) - `upload.example.slay` (for http file upload) - `pubsub.example.slay` (for the pubsub node) - `proxy.example.slay` (for file transfer proxy) - `stun.example.slay` (for stun/turn) each pointing to the ip address of your server that is going to run ejabberd. the last two are technically optional, but i would recommend them. as well as srv records for each, pointing to a domain that resolves to your server, as so: (all records are in the form `_service._proto.name IN SRV priority weight port target`) ``` _xmpp-client._tcp IN SRV 5 0 5222 example.slay. _xmpps-client._tcp IN SRV 5 0 5223 example.slay. _xmpp-server._tcp IN SRV 5 0 5269 example.slay. _xmpps-server._tcp IN SRV 5 0 5270 example.slay. ``` and ``` _xmpp-client._tcp.muc IN SRV 5 0 5222 example.slay. _xmpps-client._tcp.muc IN SRV 5 0 5223 example.slay. _xmpp-server._tcp.muc IN SRV 5 0 5269 example.slay. _xmpps-server._tcp.muc IN SRV 5 0 5270 example.slay. ``` for each of the subdomains (starting with muc). exclude `stun.example.slay`. you will then have to add one last set of srv records for stun/turn. ``` _stun._udp IN SRV 5 0 3478 stun.example.slay. _stun._tcp IN SRV 5 0 3478 stun.example.slay. _stuns._tcp IN SRV 5 0 5349 stun.example.slay. _turn._udp IN SRV 5 0 3478 stun.example.slay. _turn._tcp IN SRV 5 0 3478 stun.example.slay. _turns._tcp IN SRV 5 0 5349 stun.example.slay. ``` extra info: as a result of these records, you could technically play around with hosting xmpp on a server other than the one at `example.slay` (i.e. if you were splitting services across servers on one domain) by using the srv delegation. further info can be found at [XEP-0368](https://xmpp.org/extensions/xep-0368.html). ## step 2: open your firewall ports open ports: tcp: `80` `443` `5222` `5223` `5269` `5270` `3478` `5349` `49152-65535` udp: `3478` `49152-65535` `80` & `443` are for the web server, `5222`, `5223`, `5269` and `5270` are for xmpp, and the rest are for stun/turn. ## step 3: set up your web server and get your ssl certificates you need to: - get (an) ssl certificate(s) for your domain, as well as several subdomains, all in all: - `example.slay` - `muc.example.slay` - `upload.example.slay` - `pubsub.example.slay` - `proxy.example.slay` - `stun.example.slay` - proxypass http://127.0.0.1:5443 through to: - https://example.slay/xmpp - https://example.slay/.well-known/host-meta - https://example.slay/.well-known/host-meta.json make sure that for /xmpp you have what is necessary to proxy websockets too. if you're using nginx, increase `client_max_body_size` for http uploads. - make sure the certificate files are readable and/or in a place that is readable by the `ejabberd` user you can technically avoid using something like nginx + certbot, and use the built-in [ejabberd acme module](https://docs.ejabberd.im/admin/configuration/basic/#acme), thereby skipping this, but i am assuming you may also want to host other web services on your system, in which case you would want to reverse proxy each http service to a single https web service. ## step 4: set up postgres database we will be creating a separate database for each virtualhost, as i feel this makes things clearer, and also it easier to migrate individual virtualhosts in the future. however, there is also now the ability to only have one, as described [here](https://docs.ejabberd.im/admin/configuration/database/#default-and-new-schemas). you should follow standard postgresql installation instructions for your OS. at the time of writing, the database driver for ejabberd does [not support](https://github.com/processone/p1_pgsql/issues/6) `scram-sha-256`, so you will need to [set](https://www.postgresql.org/docs/16/runtime-config-connection.html#GUC-PASSWORD-ENCRYPTION) `password_encryption = 'md5'` in your `postgresql.conf` file. once this has been done, you should connect to your database as an admin and: 1. create an ejabberd database user with `CREATE USER ejabberd WITH PASSWORD 'your_password';`. don't forget to change the password. 2. create a database for your virtualhost with `CREATE DATABASE ejabberd_example OWNER ejabberd;`. replace `example` with something corresponding to your virtualhost. 3. import the database schema from github with the command `su -c "curl -s https://raw.githubusercontent.com/processone/ejabberd/master/sql/pg.sql | psql ejabberd_example" ejabberd` (once again replace `example`). note down the postgres ejabberd user password. ## step 5: install ejabberd now you should finally install the [system package](https://docs.ejabberd.im/admin/installation/#operating-system-packages). make sure that your build has postgresql support. make sure that the file `/etc/ejabberd/ejabberd.yml` exists, and of course, is readable by the user that runs ejabberd (almost definitely `ejabberd`), by, if necessary, copying over the example `ejabberd.yml` or `wget`/`curl`ing it from the [github repo](https://github.com/processone/ejabberd/blob/master/ejabberd.yml.example). if you are getting it from the repo, make sure the version corresponds to the version of ejabberd packaged by your os. ## step 6: ejabberd configuration - loglevel last - create docroot for uploads begin by replacing `localhost` under `hosts` with your virtualhost (e.g. `example.slay`), then list the certfiles you have obtained under `certfiles`. now set `default_db: sql` at the root level of the yaml file. this should be followed by `host_config` and the database configuration for your virtualhost, as shown below. customise each value to your setup. ``` host_config: example.slay: sql_type: pgsql sql_server: "localhost" sql_port: 5432 sql_username: "ejabberd" sql_password: "postgres_password" sql_database: "ejabberd_example" auth_method: sql auth_password_format: scram ``` under `listen`, ensure all the correct services are enabled on each port, including tls s2s on port `5270` (not default): ``` listen: - port: 5222 module: ejabberd_c2s max_stanza_size: 262144 shaper: c2s_shaper access: c2s starttls_required: true - port: 5223 tls: true module: ejabberd_c2s max_stanza_size: 262144 shaper: c2s_shaper access: c2s starttls_required: true - port: 5269 module: ejabberd_s2s_in max_stanza_size: 524288 - port: 5270 tls: true module: ejabberd_s2s_in max_stanza_size: 524288 ``` we will also be enabling the http server and the stun/turn server modules. make sure you have set `turn_ipv4_address` and `ip` to your server's ipv4 address. ``` - port: 5443 module: ejabberd_http request_handlers: /xmpp/admin: ejabberd_web_admin /xmpp/bosh: mod_bosh /xmpp/upload: mod_http_upload /xmpp/ws: ejabberd_http_ws /.well-known/host-meta: mod_host_meta /.well-known/host-meta.json: mod_host_meta - port: 3478 transport: udp module: ejabberd_stun use_turn: true turn_min_port: 49152 turn_max_port: 65535 # The server's public IPv4 address: turn_ipv4_address: 0.0.0.0 - port: 5349 transport: tcp module: ejabberd_stun use_turn: true tls: true turn_min_port: 49152 turn_max_port: 65535 ip: 0.0.0.0 turn_ipv4_address: 0.0.0.0 ``` now set `s2s_use_starttls: required` at the root. at this point you can set up some ACLs. `acls` are just the access control lists, you can also set up `access_rules` corresponding to your needs, which will be what are passed to module settings. example: ``` acl: admin: user: admin@example.slay flop: - user: flop@example.slay clown: - user: clown@example.slay access_rules: queens: allow: flop allow: clown ``` next, we will be adding some modules under `modules` and changing some settings. add abuse addresses under `mod_disco`: ``` modules: # ... mod_disco: server_info: - modules: all name: "abuse-addresses" urls: ["mailto:abuse@example.slay"] ``` add `mod_host_meta`: ``` mod_host_meta: bosh_service_url: "https://@HOST@/xmpp/bosh" websocket_url: "wss://@HOST@/xmpp/ws" ``` edit `mod_mam`, and change `assume_mam_usage` to `false` and `default` to `never` if you wish not to archive messages on the server: ``` mod_mam: db_type: sql assume_mam_usage: never default: never ``` add `mod_stun_disco` to advertise the stun service to clients, changing `0.0.0.0` and `example.slay` to your server's ip and hostname respectively: ``` mod_stun_disco: credentials_lifetime: 12h services: - host: 0.0.0.0 port: 3478 type: stun transport: udp restricted: false - host: 0.0.0.0 port: 3478 type: turn transport: udp restricted: true - host: stun.example.slay port: 5349 type: stuns transport: tcp restricted: false - host: stun.example.slay port: 5349 type: turns transport: tcp restricted: true ``` now it is time to enable MUCs (multi-user chatrooms), file proxy, http upload, and pubsub. ### mucs: make sure that you set the host to your muc subdomain, otherwise it will attempt to use `conference.example.slay`. you can also set `mam: false` in `default_room_options` to disable server-side message archiving by default. ``` mod_muc: host: muc.example.slay access: - allow access_admin: - allow: admin access_create: muc_create access_persistent: muc_create access_mam: - allow default_room_options: mam: false ``` ### file proxy: ``` mod_proxy65: access: local max_connections: 5 ``` ### http file upload: ``` mod_http_upload: put_url: https://@HOST@/xmpp/upload docroot: /var/www/ejabberdupload max_size: 1073741824 custom_headers: "Access-Control-Allow-Origin": "https://@HOST@" "Access-Control-Allow-Methods": "GET,HEAD,PUT,OPTIONS" "Access-Control-Allow-Headers": "Content-Type" ``` create the folder for the `docroot`, and make sure it is owned by the `ejabberd` user. ### pubsub: ``` mod_pubsub: access_createnode: pubsub_createnode plugins: - flat - pep force_node_config: ## Avoid buggy clients to make their bookmarks public storage:bookmarks: access_model: whitelist ``` ## step 7: start the ejabberd server! once you are done and believe everything has been set up correctly, you can optionally change the [`loglevel`](https://docs.ejabberd.im/admin/configuration/toplevel/#loglevel) at the root of the config.

# extra goodies! ## further virtualhosts? for further virtualhosts you should create a new database for each, and add them to the database part of the config. e.g.: ``` host_config: example.slay: sql_type: pgsql sql_server: "localhost" sql_port: 5432 sql_username: "ejabberd" sql_password: "postgres_password" sql_database: "ejabberd_slay" auth_method: sql auth_password_format: scram example.flop: sql_type: pgsql sql_server: "localhost" sql_port: 5432 sql_username: "ejabberd" sql_password: "postgres_password" sql_database: "ejabberd_flop" auth_method: sql auth_password_format: scram ``` there cannot be conflicts between declarations in the config file, so if you have `mod_muc`, `mod_proxy65`, `mod_http_upload` and `mod_pubsub` declared under `modules` at the root, they (as well as other configuration differences between virtualhosts) must be deleted and replicated for each virtualhost under `append_host_config` at the root. example as so: ``` append_host_config: example.flop: modules: mod_muc: host: muc.example.flop access_create: flops access_persistent: flops access: - allow access_admin: - allow: admin default_room_options: mam: false mod_proxy65: access: flops max_connections: 5 mod_http_upload: access: flops put_url: https://@HOST@/xmpp/upload docroot: /var/www/ejabberdupload max_size: 1073741824 custom_headers: "Access-Control-Allow-Origin": "https://@HOST@" "Access-Control-Allow-Methods": "GET,HEAD,PUT,OPTIONS" "Access-Control-Allow-Headers": "Content-Type" mod_pubsub: access_createnode: flops plugins: - flat - pep force_node_config: ## Avoid buggy clients to make their bookmarks public storage:bookmarks: access_model: whitelist example.flop: modules: mod_muc: hosts: - muc.example.flop access_create: local access_persistent: local access: - allow access_admin: - allow: admin default_room_options: mam: false mod_proxy65: access: local max_connections: 5 mod_http_upload: put_url: https://@HOST@/xmpp/upload docroot: /var/www/ejabberdupload max_size: 1073741824 custom_headers: "Access-Control-Allow-Origin": "https://@HOST@" "Access-Control-Allow-Methods": "GET,HEAD,PUT,OPTIONS" "Access-Control-Allow-Headers": "Content-Type" mod_pubsub: access_createnode: pubsub_createnode plugins: - flat - pep force_node_config: ## Avoid buggy clients to make their bookmarks public storage:bookmarks: access_model: whitelist ``` as you can see above, you may also want to disable access to certain services per virtualhost using ACLs, in order to e.g. prevent users on `example.slay` from creating MUCs on `muc.example.flop`.