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# nixos-mailserver: a simple mail server
# Copyright (C) 2016-2018 Robin Raymond
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>
{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.mailserver;
in
{
options.mailserver = {
enable = mkEnableOption "nixos-mailserver";
fqdn = mkOption {
type = types.str;
example = "mx.example.com";
description = "The fully qualified domain name of the mail server.";
};
domains = mkOption {
type = types.listOf types.str;
example = [ "example.com" ];
default = [];
description = "The domains that this mail server serves.";
};
messageSizeLimit = mkOption {
type = types.int;
example = 52428800;
default = 20971520;
description = "Message size limit enforced by Postfix.";
};
loginAccounts = mkOption {
type = types.attrsOf (types.submodule ({ name, ... }: {
options = {
name = mkOption {
type = types.str;
example = "user1@example.com";
description = "Username";
};
hashedPassword = mkOption {
type = with types; nullOr str;
default = null;
example = "$6$evQJs5CFQyPAW09S$Cn99Y8.QjZ2IBnSu4qf1vBxDRWkaIZWOtmu1Ddsm3.H3CFpeVc0JU4llIq8HQXgeatvYhh5O33eWG3TSpjzu6/";
description = ''
The user's hashed password. Use `htpasswd` as follows
```
nix run nixpkgs.apacheHttpd -c htpasswd -nbB "" "super secret password" | cut -d: -f2
```
Warning: this is stored in plaintext in the Nix store!
Use `hashedPasswordFile` instead.
'';
};
hashedPasswordFile = mkOption {
type = with types; nullOr path;
default = null;
example = "/run/keys/user1-passwordhash";
description = ''
A file containing the user's hashed password. Use `htpasswd` as follows
```
nix run nixpkgs.apacheHttpd -c htpasswd -nbB "" "super secret password" | cut -d: -f2
```
'';
};
aliases = mkOption {
type = with types; listOf types.str;
example = ["abuse@example.com" "postmaster@example.com"];
default = [];
description = ''
A list of aliases of this login account.
Note: Use list entries like "@example.com" to create a catchAll
that allows sending from all email addresses in these domain.
'';
};
catchAll = mkOption {
type = with types; listOf (enum cfg.domains);
example = ["example.com" "example2.com"];
default = [];
description = ''
For which domains should this account act as a catch all?
Note: Does not allow sending from all addresses of these domains.
'';
};
quota = mkOption {
type = with types; nullOr types.str;
default = null;
example = "2G";
description = ''
Per user quota rules. Accepted sizes are `xx k/M/G/T` with the
obvious meaning. Leave blank for the standard quota `100G`.
'';
};
sieveScript = mkOption {
type = with types; nullOr lines;
default = null;
example = ''
require ["fileinto", "mailbox"];
if address :is "from" "gitlab@mg.gitlab.com" {
fileinto :create "GitLab";
stop;
}
# This must be the last rule, it will check if list-id is set, and
# file the message into the Lists folder for further investigation
elsif header :matches "list-id" "<?*>" {
fileinto :create "Lists";
stop;
}
'';
description = ''
Per-user sieve script.
'';
};
sendOnly = mkOption {
type = types.bool;
default = false;
description = ''
Specifies if the account should be a send-only account.
Emails sent to send-only accounts will be rejected from
unauthorized senders with the sendOnlyRejectMessage
stating the reason.
'';
};
sendOnlyRejectMessage = mkOption {
type = types.str;
default = "This account cannot receive emails.";
description = ''
The message that will be returned to the sender when an email is
sent to a send-only account. Only used if the account is marked
as send-only.
'';
};
};
config.name = mkDefault name;
}));
example = {
user1 = {
hashedPassword = "$6$evQJs5CFQyPAW09S$Cn99Y8.QjZ2IBnSu4qf1vBxDRWkaIZWOtmu1Ddsm3.H3CFpeVc0JU4llIq8HQXgeatvYhh5O33eWG3TSpjzu6/";
};
user2 = {
hashedPassword = "$6$oE0ZNv2n7Vk9gOf$9xcZWCCLGdMflIfuA0vR1Q1Xblw6RZqPrP94mEit2/81/7AKj2bqUai5yPyWE.QYPyv6wLMHZvjw3Rlg7yTCD/";
};
};
description = ''
The login account of the domain. Every account is mapped to a unix user,
e.g. `user1@example.com`. To generate the passwords use `htpasswd` as
follows
```
nix run nixpkgs.apacheHttpd -c htpasswd -nbB "" "super secret password" | cut -d: -f2
```
'';
default = {};
};
lmtpSaveToDetailMailbox = mkOption {
type = types.enum ["yes" "no"];
default = "yes";
description = ''
If an email address is delimited by a "+", should it be filed into a
mailbox matching the string after the "+"? For example,
user1+test@example.com would be filed into the mailbox "test".
'';
};
extraVirtualAliases = mkOption {
type = let
loginAccount = mkOptionType {
name = "Login Account";
check = (account: builtins.elem account (builtins.attrNames cfg.loginAccounts));
};
in with types; attrsOf (either loginAccount (nonEmptyListOf loginAccount));
example = {
"info@example.com" = "user1@example.com";
"postmaster@example.com" = "user1@example.com";
"abuse@example.com" = "user1@example.com";
"multi@example.com" = [ "user1@example.com" "user2@example.com" ];
};
description = ''
Virtual Aliases. A virtual alias `"info@example.com" = "user1@example.com"` means that
all mail to `info@example.com` is forwarded to `user1@example.com`. Note
that it is expected that `postmaster@example.com` and `abuse@example.com` is
forwarded to some valid email address. (Alternatively you can create login
accounts for `postmaster` and (or) `abuse`). Furthermore, it also allows
the user `user1@example.com` to send emails as `info@example.com`.
It's also possible to create an alias for multiple accounts. In this
example all mails for `multi@example.com` will be forwarded to both
`user1@example.com` and `user2@example.com`.
'';
default = {};
};
forwards = mkOption {
type = with types; attrsOf (either (listOf str) str);
default = {};
example = {
"user@example.com" = "user@elsewhere.com";
};
description = ''
To forward mails to an external address. For instance,
the value {`"user@example.com" = "user@elsewhere.com";}`
means that mails to `user@example.com` are forwarded to
`user@elsewhere.com`. The difference with the
`extraVirtualAliases` option is that `user@elsewhere.com`
can't send mail as `user@example.com`. Also, this option
allows to forward mails to external addresses.
'';
default = {};
};
rejectSender = mkOption {
type = types.listOf types.str;
example = [ "@example.com" "spammer@example.net" ];
description = ''
Reject emails from these addresses from unauthorized senders.
Use if a spammer is using the same domain or the same sender over and over.
'';
default = [];
};
rejectRecipients = mkOption {
type = types.listOf types.str;
example = [ "sales@example.com" "info@example.com" ];
description = ''
Reject emails addressed to these local addresses from unauthorized senders.
Use if a spammer has found email addresses in a catchall domain but you do
not want to disable the catchall.
'';
default = [];
};
vmailUID = mkOption {
type = types.int;
default = 5000;
description = ''
The unix UID of the virtual mail user. Be mindful that if this is
changed, you will need to manually adjust the permissions of
mailDirectory.
'';
};
vmailUserName = mkOption {
type = types.str;
default = "virtualMail";
description = ''
The user name and group name of the user that owns the directory where all
the mail is stored.
'';
};
vmailGroupName = mkOption {
type = types.str;
default = "virtualMail";
description = ''
The user name and group name of the user that owns the directory where all
the mail is stored.
'';
};
mailDirectory = mkOption {
type = types.path;
default = "/var/vmail";
description = ''
Where to store the mail.
'';
};
useFsLayout = mkOption {
type = types.bool;
default = false;
description = ''
Sets whether dovecot should organize mail in subdirectories:
- /var/vmail/example.com/user/.folder.subfolder/ (default layout)
- /var/vmail/example.com/user/folder/subfolder/ (FS layout)
See https://wiki2.dovecot.org/MailboxFormat/Maildir for details.
'';
};
hierarchySeparator = mkOption {
type = types.str;
default = ".";
description = ''
The hierarchy separator for mailboxes used by dovecot for the namespace 'inbox'.
Dovecot defaults to "." but recommends "/".
This affects how mailboxes appear to mail clients and sieve scripts.
For instance when using "." then in a sieve script "example.com" would refer to the mailbox "com" in the parent mailbox "example".
This does not determine the way your mails are stored on disk.
See https://wiki.dovecot.org/Namespaces for details.
'';
};
mailboxes = mkOption {
description = ''
The mailboxes for dovecot.
Depending on the mail client used it might be necessary to change some mailbox's name.
'';
default = let
defMailBoxes = {
Trash = {
auto = "no";
specialUse = "Trash";
};
Junk = {
auto = "subscribe";
specialUse = "Junk";
};
Drafts = {
auto = "subscribe";
specialUse = "Drafts";
};
Sent = {
auto = "subscribe";
specialUse = "Sent";
};
};
in if (versionAtLeast version "20.09pre") then defMailBoxes
else (flip mapAttrsToList defMailBoxes (name: options: { inherit name; } // options));
};
certificateScheme = mkOption {
type = types.enum [ 1 2 3 ];
default = 2;
description = ''
Certificate Files. There are three options for these.
1) You specify locations and manually copy certificates there.
2) You let the server create new (self signed) certificates on the fly.
3) You let the server create a certificate via `Let's Encrypt`. Note that
this implies that a stripped down webserver has to be started. This also
implies that the FQDN must be set as an `A` record to point to the IP of
the server. In particular port 80 on the server will be opened. For details
on how to set up the domain records, see the guide in the readme.
'';
};
certificateFile = mkOption {
type = types.path;
example = "/root/mail-server.crt";
description = ''
Scheme 1)
Location of the certificate
'';
};
keyFile = mkOption {
type = types.path;
example = "/root/mail-server.key";
description = ''
Scheme 1)
Location of the key file
'';
};
certificateDirectory = mkOption {
type = types.path;
default = "/var/certs";
description = ''
Sceme 2)
This is the folder where the certificate will be created. The name is
hardcoded to "cert-<domain>.pem" and "key-<domain>.pem" and the
certificate is valid for 10 years.
'';
};
enableImap = mkOption {
type = types.bool;
default = true;
description = ''
Whether to enable IMAP with STARTTLS on port 143.
'';
};
enableImapSsl = mkOption {
type = types.bool;
default = true;
description = ''
Whether to enable IMAP with TLS in wrapper-mode on port 993.
'';
};
enableSubmission = mkOption {
type = types.bool;
default = true;
description = ''
Whether to enable SMTP with STARTTLS on port 587.
'';
};
enableSubmissionSsl = mkOption {
type = types.bool;
default = true;
description = ''
Whether to enable SMTP with TLS in wrapper-mode on port 465.
'';
};
enablePop3 = mkOption {
type = types.bool;
default = false;
description = ''
Whether to enable POP3 with STARTTLS on port on port 110.
'';
};
enablePop3Ssl = mkOption {
type = types.bool;
default = false;
description = ''
Whether to enable POP3 with TLS in wrapper-mode on port 995.
'';
};
enableManageSieve = mkOption {
type = types.bool;
default = false;
description = ''
Whether to enable ManageSieve, setting this option to true will open
port 4190 in the firewall.
The ManageSieve protocol allows users to manage their Sieve scripts on
a remote server with a supported client, including Thunderbird.
'';
};
sieveDirectory = mkOption {
type = types.path;
default = "/var/sieve";
description = ''
Where to store the sieve scripts.
'';
};
virusScanning = mkOption {
type = types.bool;
default = false;
description = ''
Whether to activate virus scanning. Note that virus scanning is _very_
expensive memory wise.
'';
};
dkimSigning = mkOption {
type = types.bool;
default = true;
description = ''
Whether to activate dkim signing.
'';
};
dkimSelector = mkOption {
type = types.str;
default = "mail";
description = ''
'';
};
dkimKeyDirectory = mkOption {
type = types.path;
default = "/var/dkim";
description = ''
'';
};
dkimKeyBits = mkOption {
type = types.int;
default = 1024;
description = ''
How many bits in generated DKIM keys. RFC6376 advises minimum 1024-bit keys.
If you have already deployed a key with a different number of bits than specified
here, then you should use a different selector (dkimSelector). In order to get
this package to generate a key with the new number of bits, you will either have to
change the selector or delete the old key file.
'';
};
debug = mkOption {
type = types.bool;
default = false;
description = ''
Whether to enable verbose logging for mailserver related services. This
intended be used for development purposes only, you probably don't want
to enable this unless you're hacking on nixos-mailserver.
'';
};
maxConnectionsPerUser = mkOption {
type = types.int;
default = 100;
description = ''
Maximum number of IMAP/POP3 connections allowed for a user from each IP address.
E.g. a value of 50 allows for 50 IMAP and 50 POP3 connections at the same
time for a single user.
'';
};
localDnsResolver = mkOption {
type = types.bool;
default = true;
description = ''
Runs a local DNS resolver (kresd) as recommended when running rspamd. This prevents your log file from filling up with rspamd_monitored_dns_mon entries.
'';
};
redis = {
address = mkOption {
type = types.str;
# read the default from nixos' redis module
default = let
cf = config.services.redis.bind;
cfdefault = if cf == null then "127.0.0.1" else cf;
ips = lib.strings.splitString " " cfdefault;
ip = lib.lists.head (ips ++ [ "127.0.0.1" ]);
isIpv6 = ip: lib.lists.elem ":" (lib.stringToCharacters ip);
in
if (ip == "0.0.0.0" || ip == "::")
then "127.0.0.1"
else if isIpv6 ip then "[${ip}]" else ip;
description = ''
Address that rspamd should use to contact redis. The default value
is read from <literal>config.services.redis.bind</literal>.
'';
};
port = mkOption {
type = types.port;
default = config.services.redis.port;
description = ''
Port that rspamd should use to contact redis. The default value is
read from <literal>config.services.redis.port<literal>.
'';
};
password = mkOption {
type = types.nullOr types.str;
default = config.services.redis.requirePass;
description = ''
Password that rspamd should use to contact redis, or null if not
required. The default value is read from
<literal>config.services.redis.requirePass<literal>.
'';
};
};
rewriteMessageId = mkOption {
type = types.bool;
default = false;
description = ''
Rewrites the Message-ID's hostname-part of outgoing emails to the FQDN.
Please be aware that this may cause problems with some mail clients
relying on the original Message-ID.
'';
};
sendingFqdn = mkOption {
type = types.str;
default = cfg.fqdn;
defaultText = "config.mailserver.fqdn";
example = "myserver.example.com";
description = ''
The fully qualified domain name of the mail server used to
identify with remote servers.
If this server's IP serves purposes other than a mail server,
it may be desirable for the server to have a name other than
that to which the user will connect. For example, the user
might connect to mx.example.com, but the server's IP has
reverse DNS that resolves to myserver.example.com; in this
scenario, some mail servers may reject or penalize the
message.
This setting allows the server to identify as
myserver.example.com when forwarding mail, independently of
`fqdn` (which, for SSL reasons, should generally be the name
to which the user connects).
Set this to the name to which the sending IP's reverse DNS
resolves.
'';
};
policydSPFExtraConfig = mkOption {
type = types.lines;
default = "";
example = ''
skip_addresses = 127.0.0.0/8,::ffff:127.0.0.0/104,::1
'';
description = ''
Extra configuration options for policyd-spf. This can be use to among
other things skip spf checking for some IP addresses.
'';
};
monitoring = {
enable = mkEnableOption "monitoring via monit";
alertAddress = mkOption {
type = types.str;
description = ''
The email address to send alerts to.
'';
};
config = mkOption {
type = types.str;
default = ''
set daemon 120 with start delay 60
set mailserver
localhost
set httpd port 2812 and use address localhost
allow localhost
allow admin:obwjoawijerfoijsiwfj29jf2f2jd
check filesystem root with path /
if space usage > 80% then alert
if inode usage > 80% then alert
check system $HOST
if cpu usage > 95% for 10 cycles then alert
if memory usage > 75% for 5 cycles then alert
if swap usage > 20% for 10 cycles then alert
if loadavg (1min) > 90 for 15 cycles then alert
if loadavg (5min) > 80 for 10 cycles then alert
if loadavg (15min) > 70 for 8 cycles then alert
check process sshd with pidfile /var/run/sshd.pid
start program "${pkgs.systemd}/bin/systemctl start sshd"
stop program "${pkgs.systemd}/bin/systemctl stop sshd"
if failed port 22 protocol ssh for 2 cycles then restart
check process postfix with pidfile /var/lib/postfix/queue/pid/master.pid
start program = "${pkgs.systemd}/bin/systemctl start postfix"
stop program = "${pkgs.systemd}/bin/systemctl stop postfix"
if failed port 25 protocol smtp for 5 cycles then restart
check process dovecot with pidfile /var/run/dovecot2/master.pid
start program = "${pkgs.systemd}/bin/systemctl start dovecot2"
stop program = "${pkgs.systemd}/bin/systemctl stop dovecot2"
if failed host ${cfg.fqdn} port 993 type tcpssl sslauto protocol imap for 5 cycles then restart
check process rspamd with pidfile /var/run/rspamd.pid
start program = "${pkgs.systemd}/bin/systemctl start rspamd"
stop program = "${pkgs.systemd}/bin/systemctl stop rspamd"
'';
description = ''
The configuration used for monitoring via monit.
Use a mail address that you actively check and set it via 'set alert ...'.
'';
};
};
borgbackup = {
enable = mkEnableOption "backup via borgbackup";
repoLocation = mkOption {
type = types.str;
default = "/var/borgbackup";
description = ''
The location where borg saves the backups.
This can be a local path or a remote location such as user@host:/path/to/repo.
It is exported and thus available as an environment variable to cmdPreexec and cmdPostexec.
'';
};
startAt = mkOption {
type = types.str;
default = "hourly";
description = "When or how often the backup should run. Must be in the format described in systemd.time 7.";
};
user = mkOption {
type = types.str;
default = "virtualMail";
description = "The user borg and its launch script is run as.";
};
group = mkOption {
type = types.str;
default = "virtualMail";
description = "The group borg and its launch script is run as.";
};
compression = {
method = mkOption {
type = types.nullOr (types.enum ["none" "lz4" "zstd" "zlib" "lzma"]);
default = null;
description = "Leaving this unset allows borg to choose. The default for borg 1.1.4 is lz4.";
};
level = mkOption {
type = types.nullOr types.int;
default = null;
description = ''
Denotes the level of compression used by borg.
Most methods accept levels from 0 to 9 but zstd which accepts values from 1 to 22.
If null the decision is left up to borg.
'';
};
auto = mkOption {
type = types.bool;
default = false;
description = "Leaves it to borg to determine whether an individual file should be compressed.";
};
};
encryption = {
method = mkOption {
type = types.enum [
"none"
"authenticated"
"authenticated-blake2"
"repokey"
"keyfile"
"repokey-blake2"
"keyfile-blake2"
];
default = "none";
description = ''
The backup can be encrypted by choosing any other value than 'none'.
When using encryption the password / passphrase must be provided in passphraseFile.
'';
};
passphraseFile = mkOption {
type = types.nullOr types.path;
default = null;
};
};
name = mkOption {
type = types.str;
default = "{hostname}-{user}-{now}";
description = ''
The name of the individual backups as used by borg.
Certain placeholders will be replaced by borg.
'';
};
locations = mkOption {
type = types.listOf types.path;
default = [cfg.mailDirectory];
description = "The locations that are to be backed up by borg.";
};
extraArgumentsForInit = mkOption {
type = types.listOf types.str;
default = ["--critical"];
description = "Additional arguments to add to the borg init command line.";
};
extraArgumentsForCreate = mkOption {
type = types.listOf types.str;
default = [ ];
description = "Additional arguments to add to the borg create command line e.g. '--stats'.";
};
cmdPreexec = mkOption {
type = types.nullOr types.str;
default = null;
description = ''
The command to be executed before each backup operation.
This is called prior to borg init in the same script that runs borg init and create and cmdPostexec.
Example:
export BORG_RSH="ssh -i /path/to/private/key"
'';
};
cmdPostexec = mkOption {
type = types.nullOr types.str;
default = null;
description = ''
The command to be executed after each backup operation.
This is called after borg create completed successfully and in the same script that runs
cmdPreexec, borg init and create.
'';
};
};
rebootAfterKernelUpgrade = {
enable = mkOption {
type = types.bool;
default = false;
example = true;
description = ''
Whether to enable automatic reboot after kernel upgrades.
This is to be used in conjunction with system.autoUpgrade.enable = true"
'';
};
method = mkOption {
type = types.enum [ "reboot" "systemctl kexec" ];
default = "reboot";
description = ''
Whether to issue a full "reboot" or just a "systemctl kexec"-only reboot.
It is recommended to use the default value because the quicker kexec reboot has a number of problems.
Also if your server is running in a virtual machine the regular reboot will already be very quick.
'';
};
};
backup = {
enable = mkEnableOption "backup via rsnapshot";
snapshotRoot = mkOption {
type = types.path;
default = "/var/rsnapshot";
description = ''
The directory where rsnapshot stores the backup.
'';
};
cmdPreexec = mkOption {
type = types.nullOr types.str;
default = null;
description = ''
The command to be executed before each backup operation. This is wrapped in a shell script to be called by rsnapshot.
'';
};
cmdPostexec = mkOption {
type = types.nullOr types.str;
default = null;
description = "The command to be executed after each backup operation. This is wrapped in a shell script to be called by rsnapshot.";
};
retain = {
hourly = mkOption {
type = types.int;
default = 24;
description = "How many hourly snapshots are retained.";
};
daily = mkOption {
type = types.int;
default = 7;
description = "How many daily snapshots are retained.";
};
weekly = mkOption {
type = types.int;
default = 54;
description = "How many weekly snapshots are retained.";
};
};
cronIntervals = mkOption {
type = types.attrsOf types.str;
default = {
# minute, hour, day-in-month, month, weekday (0 = sunday)
hourly = " 0 * * * *"; # Every full hour
daily = "30 3 * * *"; # Every day at 3:30
weekly = " 0 5 * * 0"; # Every sunday at 5:00 AM
};
description = ''
Periodicity at which intervals should be run by cron.
Note that the intervals also have to exist in configuration
as retain options.
'';
};
};
};
imports = [
./mail-server/borgbackup.nix
./mail-server/rsnapshot.nix
./mail-server/clamav.nix
./mail-server/monit.nix
./mail-server/users.nix
./mail-server/environment.nix
./mail-server/networking.nix
./mail-server/systemd.nix
./mail-server/dovecot.nix
./mail-server/opendkim.nix
./mail-server/postfix.nix
./mail-server/rspamd.nix
./mail-server/nginx.nix
./mail-server/kresd.nix
./mail-server/post-upgrade-check.nix
];
}
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