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Mail-MtPolicyd-2.05
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NAME

Mail::MtPolicyd::Cookbook::HowtoAccountingQuota - How to setup smtp level accounting and quotas

VERSION

version 2.05

SMTP level accounting and quotas with mtpolicyd

The mtpolicyd could be used to implement a smtp level accounting and quota system.

This guide explains how to setup accounting and quotas based on the sender ip on a monthly base and configurable quota limits.

The how to expects that mtpolicyd is already installed, working and assumes a MySQL database is used to hold accounting data and quota configuration.

Set up Accounting

The accounting and quota checks should be implemented in postfix smtpd_end_of_data_restrictions. If you're already using mtpolicyd for other check it may be necessary to setup a second virtual host for the accounting/quota configuration. Otherwise you can use the default port 12345 virual host.

Setup a second virtual host

First tell mtpolicyd to also listen on an addition port. In the global configuration add the new port to the port option:

port="127.0.0.1:12345,127.0.0.1:12346"

Then add a new virtual host at the end of the configuration file:

<VirtualHost 12346>
  name="accounting"
  # TODO: add plugins...
</VirtualHost>

Configure the Accounting plugin

Now add the Accounting plugin to your virtual host:

<Plugin AcctIP>
  module = "Accounting"
  fields = "client_address"
  # time_pattern = "%Y-%m"
  # table_prefix = "acct_"
</Plugin>

And the restart mtpolicyd to reload the configuration.

The plugin will create a table for every field listed in "fields". By default the table prefix is acct_ so the table name will be acct_client_address in our example. The plugin will create a row within this table for every client_address and expanded time_pattern:

mysql> select * from acct_client_address;
+----+-------------------+---------+-------+------------+---------+-----------+
| id | key               | time    | count | count_rcpt | size    | size_rcpt |
+----+-------------------+---------+-------+------------+---------+-----------+
|  1 | 2604:8d00:0:1::3  | 2015-01 |    18 |         18 |   95559 |     95559 |
|  2 | 2604:8d00:0:1::4  | 2015-01 |    21 |         21 |   99818 |     99818 |
...
+----+-------------------+---------+-------+------------+---------+-----------+

Activate the check in postfix

To active the check add the policyd to your smtpd_end_of_data_restrictions in main.cf:

smtpd_end_of_data_restrictions = check_policy_service inet:127.0.0.1:12346

If you have multiple smtpd process configured in a smtp-filter setup make sure only one smtpd is doing accounting/quota checks. Deactivate the restrictions by adding the following option the the re-inject smtpd processes in master.cf:

-o smtpd_end_of_data_restrictions=

Setup quota limits

To limit the number of messages a client_address is allowed to send add the following Quota plugin to your virtual host configuration before the Accounting plugin:

<Plugin QuotaIP>
  module = "Quota"
  field = "client_address"
  metric = "count"
  threshold = 1000
  action = "defer you exceeded your monthly limit, please insert coin"
  # time_pattern = "%Y-%m"
  # table_prefix = "acct_"
</Plugin>

Using per client_address quota limits

Create the following table structure in your MySQL database:

CREATE TABLE `relay_policies` (
  `id` int(11) NOT NULL auto_increment,
  `desc` VARCHAR(64) NOT NULL,
  `config` TEXT NOT NULL,
  PRIMARY KEY  (`id`)
) ENGINE=InnoDB;

INSERT INTO relay_policies VALUES(1, 'standard relay host', '{"quota_count":"10000"}');
INSERT INTO relay_policies VALUES(2, 'premium relay host', '{"quota_count":"100000"}');

CREATE TABLE `relay_hosts` (
  `id` int(11) NOT NULL auto_increment,
  `client_address` VARCHAR(64) NOT NULL,
  `relay_policy` int(11) NOT NULL,
  PRIMARY KEY  (`id`),
  KEY `relay_policy` (`relay_policy`),
  CONSTRAINT `relay_hosts_ibfk_1` FOREIGN KEY (`relay_policy`) REFERENCES `relay_policies` (`id`)
) ENGINE=InnoDB;

INSERT INTO relay_hosts VALUES(NULL, '2604:8d00:0:1::3', 1);
INSERT INTO relay_hosts VALUES(NULL, '2604:8d00:0:1::4', 2);

You can use the following SELECT statement to retrieve the configuration for a relay_host:

mysql> SELECT p.config FROM relay_policies p JOIN relay_hosts h ON (h.relay_policy = p.id) WHERE h.client_address = '2604:8d00:0:1::4';
+--------------------------+
| config                   |
+--------------------------+
| {"quota_count":"100000"} |
+--------------------------+
1 row in set (0.00 sec)

To load the (JSON) configuration into the mtpolicyd session variables use the SqlUserConfig plugin and this SQL statement:

<Plugin QuotaPolicyConfig>
  module = "SqlUserConfig"
  sql_query = "SELECT p.config FROM relay_policies p JOIN relay_hosts h ON (h.relay_policy = p.id) WHERE h.client_address=?"
  field = "client_address"
</Plugin>

This plugin must be added before your Accounting and Quota plugins.

To use the quota_count value instead of the default threshold adjust your Quota plugin configuration:

<Plugin QuotaIP>
  module = "Quota"
  field = "client_address"
  metric = "count"
  threshold = 1000
  uc_threshold = "quota_count"
  action = "defer you exceeded your monthly limit, please insert coin"
  # time_pattern = "%Y-%m"
  # table_prefix = "acct_"
</Plugin>

If the session variable quota_count is defined it will be used as threshold instead of the value configured in mtpolicyd.conf.

AUTHOR

Markus Benning <ich@markusbenning.de>

COPYRIGHT AND LICENSE

This software is Copyright (c) 2014 by Markus Benning <ich@markusbenning.de>.

This is free software, licensed under:

The GNU General Public License, Version 2, June 1991