add mail server guide

This commit is contained in:
Robin Raymond 2017-11-13 14:59:25 +01:00
parent 8e86234228
commit 4c8a9eb15a

247
README.md
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@ -53,7 +53,7 @@ None so far.
* rename domain to fqdn, seperate fqdn from domains
* multi domain support
### How to Deploy
### Quick Start
```nix
{ config, pkgs, ... }:
@ -88,7 +88,204 @@ None so far.
For a complete list of options, see `default.nix`.
### How to Test
## How to Set Up a 10/10 Mail Server Guide
Mail servers can be a tricky thing to set up. This guide is supposed to run you
through the most important steps to achieve a 10/10 score on `mail-tester.com`.
What you need:
* A server with a public IP (referred to as `server-IP`)
* A Fully Qualified Domain Name (`FQDN`) where your server is reachable. Note
so that other servers can find yours. Common FQDN include `mx.example.com`
(where `example.com` is a domain you own) or `mail.example.com`. The domain
is referred to as `server-domain` (`example.com` in the above example) and
the `FQDN` is referred to by `server-FQDN` (`mx.example.com` above).
* A list of domains you want to your email server to serve. (Note that this
does not have to include `server-domain`, but may of course). These will be
referred to as `domains`. As an example, `domains = [ example1.com,
example2.com ]`.
### A) Setup server
The following describes a server setup that is fairly complete. Even though
there are more possible options (see `default.nix`), these should be the most
common ones.
```nix
{ config, pkgs, ... }:
{
imports = [
(builtins.fetchTarball "https://github.com/r-raymond/nixos-mailserver/releases/tag/v2.0-rc1")
];
mailserver = {
enable = true;
fqdn = <server-FQDN>;
domains = [ <domains> ];
# A list of all login accounts. To create the password hashes, use
# mkpasswd -m sha-512 "super secret password"
loginAccounts = {
"user1@example.com" = {
hashedPassword = "$6$/z4n8AQl6K$kiOkBTWlZfBd7PvF5GsJ8PmPgdZsFGN1jPGZufxxr60PoR0oUsrvzm2oQiflyz5ir9fFJ.d/zKm/NgLXNUsNX/";
};
"user2@example.com" = { ... };
};
# Virtual aliases. These are email addresses that are forwarded to
# loginAccounts addresses.
virtualAliases = {
# address = forward address;
"info@example.com" = "user1@example.com";
"postmaster@example.com" = "user1@example.com";
"abuse@example.com" = "user1@example.com";
"user1@example2.com" = "user1@example.com";
};
};
# User Let's Encrypt certificates
certificateScheme = 3;
# Enable IMAP and POP3
enableImap = true;
enablePop3 = true;
enableImapSsl = true;
enablePop3Ssl = true;
# whether to scan inbound emails for viruses (note that this requires at least
# 1 Gb RAM for the server. Without virus scanning 256 MB RAM should be plenty)
virusScanning = false;
}
```
After a `nixos-rebuild switch --upgrade` your sever should be good to go. If
you want to use `nixops` to deploy the server, look in the subfolder `nixops`
for some inspiration.
### B) Setup everything else
#### Step 1: Set DNS entry for server
Add a DNS record to the domain `server-domain` with the following entries
| Name (Subdomain) | TTL | Type | Priority | Value |
| ---------------- | ----- | ---- | -------- | ----------------- |
| `server-FQDN` | 10800 | A | | `server-IP` |
This resolved DNS equries for `server-FQDN` to `server-IP`. You can test if your
setting is correct by
```
ping <server-FQDN>
64 bytes from <server-FQDN> (<server-IP>): icmp_seq=1 ttl=46 time=21.3 ms
...
```
Note that it can take a while until a DNS entry is propagated.
#### Step 2: Set rDNS (reverse DNS) entry for server
Wherever you have rented your server, you should be able to set reverse DNS
entries for the IP's you own. Add an entry resolving `server-IP` to
`server-FQDN`
You can test if your setting is correct by
```
host <server-IP>
<server-IP>.in-addr.arpa domain name pointer <server-FQDN>.
```
Note that it can take a while until a DNS entry is propagated.
#### Step 3: Set `MX` Records
For all `domain` in `domains` do:
* Add a `MX` record to the domain `domain`
| Name (Subdomain) | TTL | Type | Priority | Value |
| ---------------- | ----- | ---- | -------- | ----------------- |
| `domain` | | MX | 10 | `server-FQDN` |
You can test this via
```
dig -t TXT <domain>
...
;; ANSWER SECTION:
<domain> 10800 IN MX 10 <server-FQDN>
...
```
Note that it can take a while until a DNS entry is propagated.
#### Step 4: Set `SPF` Records
For all `domain` in `domains` do:
* Add a `SPF` record to the domain `domain`
| Name (Subdomain) | TTL | Type | Priority | Value |
| ---------------- | ----- | ---- | -------- | ----------------- |
| `domain` | 10800 | TXT | | `v=spf1 ip4:<server-IP> -all` |
You can check this with `dig -t TXT <domain>` similar to the last section.
Note that it can take a while until a DNS entry is propagated. If you want to
use multiple servers for your email handling, don't forget to add all server
IP's to this list.
#### Step 5: Set `DKIM` signature
For all `domain` in `domains` do:
* Go to your server and navigate to the dkim key directory (by default
`/var/dkim`. There you will find a public key for any domain in the
`domain.txt` file. It will look like
```
mail._domainkey IN TXT "v=DKIM1; r=postmaster; g=*; k=rsa; p=<really-long-key>" ; ----- DKIM default for domain.tld
```
* Add a `DKIM` record to the domain `domain`
| Name (Subdomain) | TTL | Type | Priority | Value |
| ---------------- | ----- | ---- | -------- | ----------------- |
| mail._domainkey.`domain` | 10800 | TXT | | `v=DKIM1; p=<really-long-key>` |
You can check this with `dig -t TXT <domain>` similar to the last section.
Note that it can take a while until a DNS entry is propagated.
### C) Test your Setup
Write an email to your aunt (who has been waiting for your reply far too long),
and sign up for some of the finest newsletters the Internet has.
Besides that, you can send an email to `mail-tester.com` and see how you score,
and let `http://mxtoolbox.com/` take a look at your setup, but if you followed
the steps closely then everything should be awesome!
## How to Backup
This is really easy. First off you should have a backup of your
`configuration.nix` file where you have the server config (but that is already
in a git repository right?)
Next you need to backup `/var/vmail` or whatever you have specified for the
option `mailDirectory`. This is where all the mails reside. Good options are a
cron job with `rsync` or `scp`. But really anything works, as it is simply a
folder with plenty of files in it. If your backup solution does not preserve the
owner of the files don't forget to `chown` them to `virtualMail:virtualMail` if you copy
them back (or whatever you specified as `vmailUserName`, and `vmailGoupName`).
Finally you can (optionally) make a backup of `/var/dkim` (or whatever you
specified as `dkimKeyDirectory`). If you should lose those don't worry, new ones
will be created on the fly. But you will need to repeat step `B)5` and correct
all the `dkim` keys.
## How to Test for Development
You can test the setup via `nixops`. After installation, do
@ -111,52 +308,6 @@ openssl s_client -host mail.example.com -port 143 -starttls imap
```
## How to Set Up a 10/10 Mail Server
Mail servers can be a tricky thing to set up. This guide is supposed to run you
through the most important steps to achieve a 10/10 score on `mail-tester.com`.
### Fully Qualified Domain Name
No matter how many domains you want to serve on your mail server, you need to
settle on a _Fully Qualified Domain Name_ (FQDN) where your server is reachable,
so that other servers can find yours. Common FQDN include `mx.example.com`
(where `example.com` is a domain you own) or `mail.example.com`.
After you settled on a FQDN (we will assume `mx.example.com` henceforth) you
need to
* Set a DNS entry on your domain to point to the IP of the server. For this
add a DNS record such as
| Name (Subdomain) | TTL | Type | Priority | Value |
| ---------------- | ----- | ---- | -------- | ----------------- |
| mx.example.com | 10800 | A | | `xxx.xxx.xxx.xxx` |
to your domain, where `xxx.xxx.xxx.xxx` is the IP of your server.
* Set a `rDNS` (reverse DNS) entry for your FQDN. You need to do so wherever
you have rented your server. Make sure that `xxx.xxx.xxx.xxx` resolves to
`mx.example.com`.
### MX Record
| Name (Subdomain) | TTL | Type | Priority | Value |
| ---------------- | ----- | ---- | -------- | ----------------- |
| domain1.com | | MX | 10 | mx.exmaple.com |
### Spf record
| Name (Subdomain) | TTL | Type | Priority | Value |
| ---------------- | ----- | ---- | -------- | ----------------- |
| domain1.com | 10800 | TXT | | `v=spf1 ip4:xxx.xxx.xxx.xxx -all` |
### DKIM signature
| Name (Subdomain) | TTL | Type | Priority | Value |
| ---------------- | ----- | ---- | -------- | ----------------- |
| dkim._domainkey.domain1.com | 10800 | TXT | | `v=DKIM1; p=yyyyyyyyyyyy` |
where `yyyyyyyyyyyy` is the `DKIM` signature
## A Complete Mail Server Without Moving Parts
### Used Technologies