csc-milter/README.md

# CSC Milter
This is a milter ("mail filter") for CSC. Currently it only has one purpose:
prevent clients outside of the UW network from setting the 'From' header
to a CSC address *and* using port 25 (port 587 is OK).

## Installation
As root:
```
apt install python3-milter
pip3 install .
```
Installing python3-milter will also install libmilter as a dependency.

Now open /etc/postfix/main.cf and add 'unix:/run/csc-milter/csc-milter.sock'
to the end of smptd_milters. Example:
```
smtpd_milters = unix:/var/spool/postfix/spamass/spamass.sock unix:/run/csc-milter/csc-milter.sock
```
Also open /etc/postfix/master.cf and explicitly set smtpd_milters *without*
csc-milter for the ports where csc-milter should not be running. Example:
```
submission inet n       -       n       -       -       smtpd
  -o smtpd_sasl_auth_enable=yes
  ...
  -o smtpd_milters=unix:/var/spool/postfix/spamass/spamass.sock
  ...
```
Notice how smtpd_milters above does not have the csc-milter socket path. Therefore
csc-milter will not be invoked on messages arriving on port 587 (submission).

Optional, but strongly recommended: modify milter\_connect\_macros in
/etc/postfix/main.cf to include `{daemon_port}`. This ensures that even if you
forget to exclude csc-milter from master.cf, clients using non-25 ports will not
be rejected.
Example:
```
milter_connect_macros = j v _ {daemon_name} {daemon_port}
```

Optional, but recommended: add the following to /etc/postfix/main.cf:
```
smtpd_milter_maps = cidr:/etc/postfix/smtpd_milter_map
```
Then, in /etc/postfix/smtpd\_milter\_map, add something like the following:
```
127.0.0.0/8    DISABLE
192.168.0.0/16 DISABLE
::/64          DISABLE
2001:db8::/32  DISABLE
```
This ensures that csc-milter will not be run on messages from local clients.
Replace 'DISABLE' by any additional milters which should be run. Note that
even if you do not do this, csc-milter will still accept messages from local
clients.

## Tests
Run the following from the root directory:
```
pip3 install -r test_requirements.txt
pytest
```