314 lines
14 KiB
Nix
314 lines
14 KiB
Nix
/*
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* Building: For some reason, stalwart is not served by cache.nixos.org and thus needs to be built locally.
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* Be aware that this needs some hours, about 12Gb RAM and a few Gb free space in /tmp.
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* If you only want to deploy configuration changes and no software updates, consider building on the target VM.
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* It has stalwart in its nix store and does not need to rebuild it.
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* Forwarding mails: Update the Sops-secrets in the machine directory, rebuild on the VM and deploy.
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* Everything else should happen automatically but new redirects might take up to two hours due HRZ infrastructure.
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* Using the web admin interface: Set your SSH to do portforwarding of some local port to port 80 of the VM and
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* and use your personal admin account or create one using the fallback admin password.
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* Create users with mail boxes: Go to the admin interface and create them.
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* Stalwart mailserver docs can be found at https://stalw.art/docs
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* DNS-Records: Collect the right DNS entries from the management interface and copy them to the DNS hoster. Caution:
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* Not all entries are applicable since we relay via HRZ.
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*/
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{
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config,
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lib,
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pkgs,
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...
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}: let
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inherit
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(lib)
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mkIf
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mkEnableOption
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mkOption
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;
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inherit (lib.types) listOf strMatching str path;
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cfg = config.services.mathebau-mail;
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in {
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options.services.mathebau-mail = {
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enable = mkEnableOption "mathebau mail service";
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stalwartAdmin = mkOption {
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type = path;
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description = "Path to a file that contains the stalwart fallback admin password encoded for HTTP Basic Auth";
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};
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stalwartAdminHash = mkOption {
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type = str;
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description = "String containing the hashed fallback admin password";
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};
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domains = mkOption {
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type = listOf (lib.types.submodule {
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options = {
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domain = mkOption {
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description = "Domain name that we serve. We also push its addresses to HRZ.";
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type = strMatching "^([a-z0-9]+(-[a-z0-9]+)*\.)+[a-z]{2,}$"; #Regex from https://www.oreilly.com/library/view/regular-expressions-cookbook/9781449327453/ch08s15.html
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};
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allowlistPass = mkOption {
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description = "Password file for the HRZ API that gets a list of mailaddresses that we serve";
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type = path;
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};
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virt_aliases = mkOption {
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description = "File path to a virtual alias file applicable for this domain";
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type = path;
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default = "/dev/null"; # there might not be an alias file and reading an empty one works with our implementation
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};
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};
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});
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};
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};
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config = mkIf cfg.enable {
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services = {
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stalwart-mail = {
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enable = true;
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openFirewall = true;
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settings = {
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server = {
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lookup.default.hostname = "fb04184.mathematik.tu-darmstadt.de"; # Because the DNS PTR of 130.83.2.184 is this and this should be used in SMTP EHLO.
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listener = {
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# Do not enable JMAP until https://github.com/stalwartlabs/mail-server/issues/618 is resolved!
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# Luckily, this bug does not apply to IMAP.
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"smtp" = {
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bind = ["[::]:25"];
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protocol = "smtp";
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};
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"submissions" = {
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bind = ["[::]:465"];
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protocol = "smtp";
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tls.implicit = true;
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};
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"imaptls" = {
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bind = ["[::]:993"];
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protocol = "imap";
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tls.implicit = true;
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};
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"management" = {
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# Cthulhu forwards requests for http://fb04184.mathematik.tu-darmstadt.de/.well-known/acme-challenge/ http://imap.mathebau.de/.well-known/acme-challenge/ and http://smtp.mathebau.de/.well-known/acme-challenge/
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# for TLS certificate challenge validation
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# whereas the rest of the management interface is not available publically.
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# It can be reached via SSH and portforwarding.
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bind = ["[::]:80"];
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protocol = "http";
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};
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};
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};
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acme.letsencrypt = {
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directory = "https://acme-v02.api.letsencrypt.org/directory"; # This setting is necessary for this block to be activated
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challenge = "http-01";
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contact = ["root@mathebau.de"];
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domains = ["fb04184.mathematik.tu-darmstadt.de" "imap.mathebau.de" "smtp.mathebau.de"];
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default = true;
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};
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spam.header.is-spam = "Dummyheader"; # disable moving to spam which would conflict with forwarding
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auth = {
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# TODO check if HRZ conforms to these standards and we can validate them strictly
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dkim.verify = "relaxed";
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arc.verify = "relaxed";
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dmarc.verify = "relaxed";
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iprev.verify = "relaxed";
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spf.verify.ehlo = "relaxed";
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spf.verify.mail-from = "relaxed";
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};
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# Forward outgoing mail to HRZ or mail VMs.
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# see https://stalw.art/docs/smtp/outbound/routing/ relay host example
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queue.outbound = {
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next-hop = [
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{
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"if" = "rcpt_domain = 'lists.mathebau.de'";
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"then" = "'mailman'";
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}
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{
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"if" = "is_local_domain('', rcpt_domain)";
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"then" = "'local'";
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}
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{"else" = "'hrz'";}
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];
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tls = {
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# we only talk to HRZ and our own VMs anyway
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mta-sts = "disable";
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dane = "disable";
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starttls = "optional"; # e.g. Lobon does not offer starttls
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};
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};
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remote."hrz" = {
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address = "mailout.hrz.tu-darmstadt.de";
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port = 25;
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protocol = "smtp";
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tls.implicit = false; # Don't assume TLS on this port but use STARTTLS
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};
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remote."mailman" = {
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address = "lobon.mathebau.de"; # must be created in DNS as a MX record because this field does not accept ip addresses.
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port = 25;
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protocol = "smtp";
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tls.implicit = false; # Don't assume TLS on this port but use STARTTLS
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};
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session.rcpt = {
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# In order to accept mail that we only forward
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# without having to generate an account.
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# Invalid addresses are filtered by DFN beforehand.
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catch-all = true;
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relay = [
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{
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"if" = "!is_empty(authenticated_as) || rcpt_domain == 'lists.mathebau.de'";
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"then" = true;
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}
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{"else" = false;}
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];
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};
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# Stalwart gets its configuration from two places: A TOML configuration file that we control in this module
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# and from a database that can be configured from web management interface or via Rest API.
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# We here define what comes from the TOML-file and especially add "sieve.trusted.scripts.*" to the default ones
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# because only TOML-based keys may use macros to load files from disk.
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# We want this to be able to load our sieve-script for mail forwarding.
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config.local-keys =
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[
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"store.*"
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"directory.*"
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"tracer.*"
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"server.*"
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"!server.blocked-ip.*"
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"authentication.fallback-admin.*"
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"cluster.node-id"
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"storage.data"
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"storage.blob"
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"storage.lookup"
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"storage.fts"
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"storage.directory"
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"lookup.default.hostname"
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"certificate.*"
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] # the default ones
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++ ["sieve.trusted.scripts.*"]; #for macros to be able to include our redirection script
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sieve.trusted.scripts.redirects.contents = "%{file:/tmp/virt_aliases}%"; # generated redirect script
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session.data.script = "'redirects'";
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authentication.fallback-admin = {
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user = "admin";
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# see passwd on azathoth for plaintext or machine secret in encoded format for HTTP Basic AUTH
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secret = cfg.stalwartAdminHash;
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};
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};
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};
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};
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environment.persistence.${config.impermanence.name} = {
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directories = [
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"/var/lib/stalwart-mail"
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];
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files = ["/root/.ssh/known_hosts"]; # for the backup server bragi
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};
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# Update HRZ allowlist
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# For account details see https://www-cgi.hrz.tu-darmstadt.de/mail/
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# will stop working if no valid TUIDs are associated to our domain.
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systemd = {
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timers."mailAllowlist" = {
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wantedBy = ["timers.target"];
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timerConfig = {
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OnBootSec = "1h"; # Run every hour
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OnUnitActiveSec = "1h";
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RandomizedDelaySec = "10m"; # prevent overload on regular intervals
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Unit = "mailAllowlist.service";
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};
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};
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services = {
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"mailAllowlist" = {
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description = "Allowlist update: Post the mail addresses to the HRZ allowllist";
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script = let
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scriptTemplate = {
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domain,
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allowlistPass,
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...
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}: ''
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echo "process ${domain}"
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# This line gets the available mailboxes from stalwart's Rest API, searches for their addresses and collects them to a file for submission.
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${pkgs.curl}/bin/curl -s --header "authorization: Basic $(<${cfg.stalwartAdmin})" http://localhost/api/principal | ${pkgs.gnugrep}/bin/grep -o -e "[A-Za-z0-9.!#\$%&'*+-/=?^_{|}~]*@${domain}" | tee /tmp/addresses
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# This line searches for available redirects and adds them to the submission file.
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${pkgs.gnugrep}/bin/grep -o -e "[A-Za-z0-9.!#\$%&'*+-/=?^_{|}~]*@${domain}" /tmp/virt_aliases >> /tmp/addresses # This doesn't catch all RFC conform local parts. Improve if you need.
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# Post local-parts to HRZ, see https://www-cgi.hrz.tu-darmstadt.de/mail/index.php?bereich=whitelist_upload
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${pkgs.curl}/bin/curl -s https://www-cgi.hrz.tu-darmstadt.de/mail/whitelist-update.php -F emaildomain=${domain} -F password=$(cat ${allowlistPass}) -F emailliste=@/tmp/addresses -F meldungen=voll
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# Cleanup submission file
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rm /tmp/addresses
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'';
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in
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lib.strings.concatStringsSep "" (map scriptTemplate cfg.domains);
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serviceConfig = {
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Type = "oneshot";
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User = "stalwart-mail";
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NoNewPrivileges = true;
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# See https://www.man7.org/linux/man-pages/man5/systemd.exec.5.html
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PrivateTmp = false; # allow access to sieve script
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ProtectHome = true;
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ReadOnlyPaths = "/";
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ReadWritePaths = "/tmp";
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InaccessiblePaths = "-/lost+found";
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PrivateDevices = true;
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PrivateUsers = true;
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ProtectHostname = true;
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ProtectClock = true;
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ProtectKernelTunables = true;
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ProtectKernelModules = true;
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ProtectKernelLogs = true;
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ProtectControlGroups = true;
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LockPersonality = true;
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MemoryDenyWriteExecute = true;
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RestrictRealtime = true;
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RestrictSUIDSGID = true;
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};
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};
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"stalwart-mail" = {
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restartTriggers = lib.attrsets.mapAttrsToList (_: aliaslist: aliaslist.sopsFile) config.sops.secrets; # restart if secrets, especially alias files, have changed.
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serviceConfig.PrivateTmp = lib.mkForce false; # enable access to generated Sieve script
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};
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"virt-aliases-generator" = {
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description = "Virtual Aliases Generator: Generate a sieve script from the virtual alias file";
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script = lib.strings.concatStringsSep "" (["${pkgs.alias-to-sieve}/bin/alias_to_sieve "] ++ map (x: "${x.virt_aliases} ${x.domain} ") cfg.domains ++ ["> /tmp/virt_aliases"]);
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wantedBy = ["stalwart-mail.service"]; # Rerun on stalwart restart because forwardings may have changed.
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serviceConfig = {
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Type = "oneshot";
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User = "stalwart-mail";
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NoNewPrivileges = true;
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# See https://www.man7.org/linux/man-pages/man5/systemd.exec.5.html
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PrivateTmp = false;
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ProtectHome = true;
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ReadOnlyPaths = "/";
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ReadWritePaths = "/tmp";
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InaccessiblePaths = "-/lost+found";
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PrivateDevices = true;
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PrivateUsers = true;
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ProtectHostname = true;
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ProtectClock = true;
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ProtectKernelTunables = true;
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ProtectKernelModules = true;
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ProtectKernelLogs = true;
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ProtectControlGroups = true;
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LockPersonality = true;
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MemoryDenyWriteExecute = true;
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RestrictRealtime = true;
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RestrictSUIDSGID = true;
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};
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};
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};
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};
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# Backups
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services.borgbackup.jobs.mail = {
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paths = [
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"/var/lib/stalwart-mail/data"
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];
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encryption.mode = "none"; # Otherwise the key is next to the backup or we have human interaction.
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environment = {
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BORG_RSH = "ssh -i /run/secrets/backupKey";
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# “Borg ensures that backups are not created on random drives that ‘just happen’ to contain a Borg repository.”
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# https://borgbackup.readthedocs.io/en/stable/deployment/automated-local.html
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# We don't want this in order to not need to persist borg cache and simplify new deployments.
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BORG_UNKNOWN_UNENCRYPTED_REPO_ACCESS_IS_OK = "yes";
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};
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repo = "borg@192.168.1.11:kaluut"; # TODO for https://gitea.mathebau.de/Fachschaft/nixConfig/issues/33
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startAt = "daily";
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user = "root";
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group = "root";
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};
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};
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}
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