---
title: "pike Module"
description: "The module provides a simple mechanism for DOS protection - DOS based on floods at network level."
---

## Admin Guide


### 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


#### OpenSIPS Modules


The following modules must be loaded before this module:


- *No dependencies on other OpenSIPS modules*.


#### External Libraries or Applications


The following libraries or applications must be installed before
running OpenSIPS 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.*


```opensips title="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.*


```opensips title="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.


> [!NOTE]
> If the *remove_latency*
> value is lower than *sampling_time_unit* value,
> nodes might expire before being unblocked, therefore losing some
> UNBLOCK events. In order to prevent this, if the
> *remove_latency* is lower, OpenSIPS internally
> forces its value to *sampling_time_unit + 1*.


*Default value is 120.*


```opensips title="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).*


```opensips title="Set check_route parameter"
...
modparam("pike", "check_route", "pike")
...
route[pike]{
    if ($si==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).*


```opensips title="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.


```opensips title="pike_check_req usage"
...
if (!pike_check_req()) { exit; };
...
```


### Exported MI Functions


#### pike:list


Replaces obsolete MI command: *pike_list*.


Lists the nodes in the pike tree.


Name: *pike:list*


Parameters: *none*


MI FIFO Command Format:


```bash
opensips-cli -x mi pike:list
```


#### pike:rm


Replaces obsolete MI command: *pike_rm*.


Remove a node from the pike tree by IP address.


Name: *pike:rm*


Parameters:


- *IP* - IP address currently blocked.


MI FIFO Command Format:


```bash
opensips-cli -x mi pike:rm 10.0.0.106
```


### 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.


### Provided Status/Report Identifiers


The module provides the "pike" Status/Report group, only with
the "main"/default SR identifier.


There is no usefull status published by the module.


In terms of reports/logs, the following events will be reported:


- IP X.Y.Z.W detected as flooding


For how to access and use the Status/Report information, please see
[Status/Report Interface](../../docs/manual/Interface-StatusReport.md).


## Developer Guide


One single tree (for both IPv4 and IPv6) is used. Each node contains a byte, the IP
addresses stretching from root to the leafs.


```c title="Tree of IP addresses"
	   / 193 - 175 - 132 - 164
tree root /                  \ 142
	  \ 195 - 37 - 78 - 163
	   \ 79 - 134
```


To detect the whole address, step by step, from the root to the leafs, the nodes corresponding
to each byte of the ip address are expanded. In order to be expended a node has to be hit
for a given number of times (possible by different addresses; in the previous example, the
node "37" was expended by the 195.37.78.163 and 195.37.79.134 hits).


For 193.175.132.164 with x= reqs_density_per_unit:


- After first req hits -> the "193" node is built.
- After x more hits, the "175" node is build; the hits of
"193" node are split between itself and its child--both of them gone
have x/2.
- And so on for node "132" and "164".
- Once "164" build the entire address can be found in the
tree. "164" becomes a leaf. After it will be hit as a leaf for x
times, it will become "RED" (further request from this address will
be blocked).


So, to build and block this address were needed 3*x hits. Now, if reqs start coming from
193.175.132.142, the first 3 bytes are already in the tree (they are shared with the previous
address), so I will need only x hits (to build node "142" and to make it
"RED") to make this address also to be blocked.  This is the reason for the
variable number of hits necessary to block an IP.


The maximum number of hits to turn an address red are (n is the address's number of bytes):


1 (first byte) + x (second byte) + (x / 2) * (n - 2) (for the rest of the bytes) + (n - 1)
(to turn the node to red).


So, for IPv4 (n = 4) will be 3x and for IPv6 (n = 16) will be 9x. The minimum number of hits
to turn an address red is x.
<!-- CONTRIBUTORS -->

### License

All documentation files (i.e. .md extension) are licensed under the Creative Common License 4.0
