# &adminguide;

## Overview

The module provides a simple mechanism for DOS protection - DOS based on floods at network level. The module keeps trace of all (or selected ones) IPs of incoming SIP traffic (as source IP) and blocks the ones that exceeded some limit. Works simultaneous for IPv4 and IPv6 addresses.

The module does not implement any actions on blocking - it just simply reports that there is a high traffic from an IP; what to do, is the administator decision (via scripting).

## How to use

There are 2 ways of using this module (as detecting flood attacks and as taking the right action to limit the impact on the system):

- manual - from routing script you can force the check of the source IP of an incoming requests, using "pike_check_req" function. Note that this checking works only for SIP requests and you can decide (based on scripting logic) what source IPs to be monitored and what action to be taken when a flood is detected.

- automatic - the module will install internal hooks to catch all incoming requests and replies (even if not well formed from SIP point of view) - more or less the module will monitor all incoming packages (from the network) on the SIP sockets. Each time the source IP of a package needs to be analyse (to see if trusted or not), the module will run a script route - see "check_route" module parameter -, where, based on custom logic, you can decide if that IP needs to be monitored for flooding or not. As action, when flood is detected, the module will automatically drop the packages.

## Dependencies

### &osips; Modules

The following modules must be loaded before this module:

- No dependencies on other &osips; modules.

### External Libraries or Applications

The following libraries or applications must be installed before running &osips; with this module loaded:

- None.

## Exported Parameters

### `sampling_time_unit` (integer)

Time period used for sampling (or the sampling accuracy ;-) ). The smaller the better, but slower. If you want to detect peaks, use a small one. To limit the access (like total number of requests on a long period of time) to a proxy resource (a gateway for ex), use a bigger value of this parameter.

IMPORTANT: a too small value may lead to performance penalties due timer process overloading.

Default value is 2.

#### Set `sampling_time_unit` parameter

    ...
    modparam("pike", "sampling_time_unit", 10)
    ...

### `reqs_density_per_unit` (integer)

How many requests should be allowed per sampling_time_unit before blocking all the incoming request from that IP. Practically, the blocking limit is between ( let's have x=reqs_density_per_unit) x and 3*x for IPv4 addresses and between x and 8*x for ipv6 addresses.

Default value is 30.

#### Set `reqs_density_per_unit` parameter

    ...
    modparam("pike", "reqs_density_per_unit", 30)
    ...

### `remove_latency` (integer)

For how long the IP address will be kept in memory after the last request from that IP address. It's a sort of timeout value.

Default value is 120.

#### Set `remove_latency` parameter

    ...
    modparam("pike", "remove_latency", 130)
    ...

### `check_route` (integer)

The name of the script route to be triggers (in automatic way) when a package is received from the network. If you do a "drop" in this route, it will indicate to the module that the source IP of the package does not need to be monitored. Otherwise, the source IP will be automatically monitered.

By defining this parameter, the automatic checking mode is enabled.

Default value is NONE (no auto mode).

#### Set `check_route` parameter

    ...
    modparam("pike", "check_route", "pike")
    ...
    route[pike]{
        if (src_ip==111.222.111.222)  /*trusted, do not check it*/
            drop;
        /* all other IPs are checked*/
    }
    ....

### `pike_log_level` (integer)

Log level to be used by module to auto report the blocking (only first time) and unblocking of IPs detected as source of floods.

Default value is 1 (L_WARN).

#### Set `pike_log_level` parameter

    ...
    modparam("pike", "pike_log_level", -1)
    ...

## Exported Functions

### `pike_check_req()`

Process the source IP of the current request and returns false if the IP was exceeding the blocking limit.

Return codes:

- 1 (true) - IP is not to be blocked or internal error occurred.

  IMPORTANT: in case of internal error, the function returns true to avoid reporting the current processed IP as blocked.

- -1 (false) - IP is source of flooding, being previously detected

- -2 (false) - IP is detected as a new source of flooding - first time detection

This function can be used from REQUEST_ROUTE.

#### `pike_check_req` usage

    ...
    if (!pike_check_req()) { exit; };
    ...

## Exported MI Functions

### `pike_list`

Lists the nodes in the pike tree.

Name: pike_list

Parameters:

- IP - IP address currently blocked.

MI FIFO Command Format:

    		:pike_list:_reply_fifo_file_
    		_empty_line_

### `pike_rm`

Remove a node from the pike tree by IP address.

Name: pike_rm

Parameters: none

MI FIFO Command Format:

    		:pike_list:_reply_fifo_file_
    		_empty_line_

## Exported Events

### `E_PIKE_BLOCKED`

This event is raised when the pike module decides that an IP should be blocked.

Parameters:

- ip - the IP address that has been blocked.