mirror of
https://github.com/simple-login/app.git
synced 2024-11-14 12:47:18 +08:00
51 lines
1.3 KiB
Markdown
51 lines
1.3 KiB
Markdown
Some email services like Gmail, Protonmail, etc don't have a strict SPF record (`-all`) to support the "classic" email forwarding
|
|
that is usually used for group mailing list. In this scenario, an email is sent to a group is forwarded as-is,
|
|
breaking therefore the SPF.
|
|
|
|
A malicious hacker could use this security fail to impersonate your alias via the reverse-alias. This rarely happens
|
|
as the reverse-alias is generated randomly and is unique for each sender.
|
|
|
|
However if you want to prevent this kind of attack, you can enforce the SPF policy even if your mailbox uses a "soft" policy.
|
|
|
|
1) Install `postfix-pcre`
|
|
|
|
```bash
|
|
apt install -y postfix-pcre
|
|
```
|
|
|
|
2) Add `/etc/postfix/body_checks.pcre` file with the following content
|
|
|
|
```
|
|
/^X-SimpleLogin-Client-IP:/ IGNORE
|
|
```
|
|
|
|
3) Add `/etc/postfix/client_headers.pcre` with the following content
|
|
|
|
```
|
|
/^([0-9a-f:.]+)$/ prepend X-SimpleLogin-Client-IP: $1
|
|
```
|
|
|
|
4) Add the following lines to your Postfix config file at `/etc/postfix/main.cf`
|
|
|
|
```
|
|
body_checks = pcre:/etc/postfix/body_checks.pcre
|
|
smtpd_client_restrictions = pcre:/etc/postfix/client_headers.pcre
|
|
```
|
|
|
|
5) Enable `ENFORCE_SPF` in your SimpleLogin config file
|
|
|
|
```
|
|
ENFORCE_SPF=true
|
|
```
|
|
|
|
6) Restart Postfix
|
|
|
|
```bash
|
|
systemctl restart postfix
|
|
```
|
|
|
|
7) Restart SimpleLogin mail handler
|
|
|
|
```bash
|
|
sudo docker restart sl-email
|
|
```
|