347 lines
10 KiB
Nix
347 lines
10 KiB
Nix
{ config, lib, pkgs, ... }:
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let
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cfg = config.sbruder.mailserver;
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certDir = config.security.acme.certs."${cfg.fqdn}".directory;
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in
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{
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options.sbruder.mailserver = with lib; with lib.types; {
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enable = mkEnableOption "simple mail server";
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fqdn = mkOption {
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type = str;
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description = ''
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FQDN of the mail server
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It needs to have a matching reverse DNS record. Also, an acme
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certificate with this name has to be present.
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'';
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example = "mail.example.com";
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};
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storage = mkOption {
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type = path;
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description = "Location of the storage for mails";
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default = "/var/vmail";
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};
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domains = mkOption {
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type = listOf str;
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description = "Domains to serve";
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example = [ "example.com" "example.org" ];
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};
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users = mkOption {
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type = listOf (submodule {
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options = {
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address = mkOption {
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type = str;
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description = "Primary e-mail address of the user";
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example = "jdoe@example.com";
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};
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passwordHash = mkOption {
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type = str;
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description = ''
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Bcrypt hash of the user’s password. Please note that it will be
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world-readable in the nix store.
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You can generate a password with `nix run nixpkgs.apacheHttpd -c
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htpasswd -nBC 12 "" | cut -d: -f2`
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'';
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example = "$2y$05$SHxhwVGx.XCd19HAcb1NKuidUxW1BwU7GeO0ZIcMTc5t2uZoYLVRK";
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};
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aliases = mkOption {
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type = listOf str;
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description = ''
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A list of aliases for the user.
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If multiple users have the same alias defined, mail will be
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delivered to both of them.
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'';
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default = [ ];
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example = [
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"j.doe@example.com"
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"jane.doe@example.com"
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"postmaster@example.com"
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];
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};
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};
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});
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description = "Users of the mail server";
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};
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cleanHeaders = mkOption {
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type = listOf str;
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description = "A list of regular expressions that define what headers are filtered";
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default = [
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"/^\\s*Received:/"
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"/^\\s*User-Agent:/"
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"/^\\s*X-Mailer:/"
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"/^\\s*X-Originating-IP:/"
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];
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};
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rejectSenders = mkOption {
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type = listOf str;
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description = "A list of senders to reject mails from";
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default = [ ];
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example = [
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"newsletter@example.com"
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"spammer@example.com"
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];
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};
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};
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config = lib.mkIf cfg.enable {
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# Users and groups
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users.users.vmail = {
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uid = 10000;
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group = "vmail";
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home = cfg.storage;
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createHome = true;
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};
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users.groups.vmail.gid = 10000;
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# Firewall
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networking.firewall.allowedTCPPorts = [
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143 # IMAP
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25 # SMTP
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587 # SMTP submission
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];
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# Service dependencies
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systemd.services.dovecot2 = {
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wants = [ "acme-finished-${cfg.fqdn}.target" ];
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after = [ "acme-finished-${cfg.fqdn}.target" ];
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};
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systemd.services.postfix = {
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wants = [ "acme-finished-${cfg.fqdn}.target" ];
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requires = [ "dovecot2.service" ];
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after = [ "acme-finished-${cfg.fqdn}.target" "dovecot2.service" ];
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};
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# Reload on certificate renewal
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security.acme.certs."${cfg.fqdn}".postRun = ''
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if systemctl is-active dovecot2; then
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systemctl --no-block reload dovecot2
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fi
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if systemctl is-active postfix; then
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systemctl --no-block reload postfix
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fi
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'';
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# Postfix
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security.dhparams.params.postfix = { };
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services.postfix =
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let
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listToString = lib.concatStringsSep ",";
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valiases =
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let
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# List of attribute sets with single key-value pair
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plainAliases = (lib.flatten
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(map
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({ address, aliases, ... }:
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map
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(alias: { "${alias}" = address; })
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(aliases ++ lib.singleton address))
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cfg.users));
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# Attribute set with every alias mapped to a list of receivers
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mergedAliases = (lib.attrsets.foldAttrs
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(val: col: lib.singleton val ++ col)
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[ ]
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plainAliases);
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# Contents of the aliases file
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aliasesString = (lib.concatStringsSep
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"\n"
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(lib.mapAttrsToList
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(alias: addresses: "${alias} ${listToString addresses}")
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mergedAliases));
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in
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pkgs.writeText
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"valiases"
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aliasesString;
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access_sender = pkgs.writeText
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"access_sender"
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(lib.concatMapStringsSep
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"\n"
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(sender: "${sender} REJECT")
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cfg.rejectSenders);
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submissionHeaderCleanupRules = pkgs.writeText "submission_header_cleanup_rules"
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(lib.concatMapStringsSep
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"\n"
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(regex: "${regex} IGNORE")
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cfg.cleanHeaders);
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in
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{
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enable = true;
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enableSubmission = true;
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hostname = cfg.fqdn;
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networksStyle = "host";
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sslCert = "${certDir}/fullchain.pem";
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sslKey = "${certDir}/key.pem";
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recipientDelimiter = "+";
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mapFiles = {
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inherit access_sender valiases;
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};
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config = {
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# General
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smtpd_banner = "${cfg.fqdn} ESMTP NO UCE";
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disable_vrfy_command = true; # disable check if mailbox exists
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enable_long_queue_ids = true; # better for debugging
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strict_rfc821_envelopes = true; # only accept properly formatted envelope
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message_size_limit = "50331648"; # 48 MiB
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virtual_mailbox_domains = listToString cfg.domains;
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virtual_mailbox_maps = "hash:/var/lib/postfix/conf/valiases";
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virtual_alias_maps = "hash:/var/lib/postfix/conf/valiases";
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virtual_transport = "lmtp:unix:/run/dovecot2/dovecot-lmtp";
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smtpd_recipient_restrictions = listToString [
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"reject_non_fqdn_recipient"
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"reject_rbl_client ix.dnsbl.manitu.net"
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"reject_unknown_recipient_domain"
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"reject_unverified_recipient"
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];
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smtpd_client_restrictions = listToString [
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"reject_rbl_client ix.dnsbl.manitu.net"
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"reject_unknown_client_hostname"
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];
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smtpd_sender_restrictions = listToString [
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"check_sender_access hash:/var/lib/postfix/conf/access_sender"
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"reject_non_fqdn_sender"
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"reject_unknown_sender_domain"
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];
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# generated 2021-02-04, Mozilla Guideline v5.6, Postfix 3.5.6, OpenSSL 1.1.1i, intermediate configuration
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# https://ssl-config.mozilla.org/#server=postfix&version=3.5.6&config=intermediate&openssl=1.1.1i&guideline=5.6
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smtpd_tls_security_level = "may";
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smtpd_tls_auth_only = "yes";
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smtpd_tls_mandatory_protocols = "!SSLv2, !SSLv3, !TLSv1, !TLSv1.1";
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smtpd_tls_protocols = "!SSLv2, !SSLv3, !TLSv1, !TLSv1.1";
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smtpd_tls_mandatory_ciphers = "medium";
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smtpd_tls_loglevel = "1";
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tls_medium_cipherlist = listToString [
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"ECDHE-ECDSA-AES128-GCM-SHA256"
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"ECDHE-RSA-AES128-GCM-SHA256"
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"ECDHE-ECDSA-AES256-GCM-SHA384"
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"ECDHE-RSA-AES256-GCM-SHA384"
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"ECDHE-ECDSA-CHACHA20-POLY1305"
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"ECDHE-RSA-CHACHA20-POLY1305"
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"DHE-RSA-AES128-GCM-SHA256"
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"DHE-RSA-AES256-GCM-SHA384"
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];
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tls_preempt_cipherlist = "no";
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smtpd_tls_dh1024_param_file = config.security.dhparams.params.postfix.path;
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};
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submissionOptions = {
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smtpd_tls_security_level = "encrypt";
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smtpd_sasl_auth_enable = "yes";
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smtpd_sasl_type = "dovecot";
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smtpd_sasl_path = "/run/dovecot2/auth";
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smtpd_sender_login_maps = "hash:/etc/postfix/valiases";
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smtpd_recipient_restrictions = listToString [ ];
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smtpd_client_restrictions = listToString [
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"permit_sasl_authenticated"
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"reject"
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];
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smtpd_sender_restrictions = listToString [
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"reject_sender_login_mismatch"
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];
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cleanup_service_name = "submission-header-cleanup";
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};
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masterConfig = {
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submission-header-cleanup = {
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private = false;
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maxproc = 0;
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command = "cleanup";
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args = [ "-o" "header_checks=pcre:${submissionHeaderCleanupRules}" ];
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};
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};
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};
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# Dovecot
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services.dovecot2 =
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let
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postfixCfg = config.services.postfix;
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passdb = pkgs.writeText "dovecot-users"
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(lib.concatMapStringsSep
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"\n"
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({ address, passwordHash, ... }: "${address}:{BLF-CRYPT}${passwordHash}")
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cfg.users);
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in
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{
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enable = true;
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enableLmtp = true;
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enablePAM = false;
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mailUser = "vmail";
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mailGroup = "vmail";
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mailLocation = "maildir:${cfg.storage}/%d/%n";
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sslServerCert = "${certDir}/fullchain.pem";
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sslServerKey = "${certDir}/key.pem";
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extraConfig = ''
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# generated 2021-02-04, Mozilla Guideline v5.6, Dovecot 2.3.13, OpenSSL 1.1.1i, intermediate configuration
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# https://ssl-config.mozilla.org/#server=dovecot&version=2.3.13&config=intermediate&openssl=1.1.1i&guideline=5.6
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ssl = required
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ssl_min_protocol = TLSv1.2
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ssl_cipher_list = 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 = no
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service imap-login {
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inet_listener imap {
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}
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}
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service lmtp {
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unix_listener dovecot-lmtp {
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mode = 0600
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user = ${postfixCfg.user}
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group = ${postfixCfg.group}
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}
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}
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passdb {
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driver = passwd-file
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args = username_format=%u ${passdb}
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}
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userdb {
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driver = static
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args = uid=vmail gid=vmail home=${cfg.storage}/%d/%n
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}
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service auth {
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unix_listener auth {
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mode = 0660
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user = ${postfixCfg.user}
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group = ${postfixCfg.group}
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}
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}
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lda_mailbox_autosubscribe = yes
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lda_mailbox_autocreate = yes
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'';
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};
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};
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}
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