name mode size
doc 040000
Makefile 100644 292B
README 100644 6.43kB
ip_tree.c 100644 8.71kB
ip_tree.h 100644 2.62kB
pike.c 100644 4.07kB
pike_funcs.c 100644 8.96kB
pike_funcs.h 100644 1.09kB
pike_mi.c 100644 2.81kB
pike_mi.h 100644 1.11kB
timer.c 100644 2.82kB
timer.h 100644 1.49kB
pike Module Bogdan-Andrei Iancu Edited by Bogdan-Andrei Iancu Copyright � 2003 FhG FOKUS Revision History Revision $Revision$ $Date: 2008-08-06 12:08:33 +0200 (Mi, 06 Aug 2008) $ __________________________________________________________ Table of Contents 1. Admin Guide 1.1. Overview 1.2. Dependencies 1.2.1. Kamailio Modules 1.2.2. External Libraries or Applications 1.3. Exported Parameters 1.3.1. sampling_time_unit (integer) 1.3.2. reqs_density_per_unit (integer) 1.3.3. remove_latency (integer) 1.3.4. pike_log_level (integer) 1.4. Exported Functions 1.4.1. pike_check_req() 1.5. Exported MI Functions 1.5.1. pike_list 2. Developer Guide List of Examples 1.1. Set sampling_time_unit parameter 1.2. Set reqs_density_per_unit parameter 1.3. Set remove_latency parameter 1.4. Set pike_log_level parameter 1.5. pike_check_req usage 2.1. Tree of IP addresses Chapter 1. Admin Guide 1.1. Overview The module keeps trace of all (or selected ones) incoming request's IP source 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). 1.2. Dependencies 1.2.1. Kamailio Modules The following modules must be loaded before this module: * No dependencies on other Kamailio modules. 1.2.2. External Libraries or Applications The following libraries or applications must be installed before running Kamailio with this module loaded: * None. 1.3. Exported Parameters 1.3.1. sampling_time_unit (integer) Time period used for sampling (or the sampling accuracy ;-) ). The smaller the better, but slower. If you want to detect peeks, 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. Example 1.1. Set sampling_time_unit parameter ... modparam("pike", "sampling_time_unit", 10) ... 1.3.2. 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. Example 1.2. Set reqs_density_per_unit parameter ... modparam("pike", "reqs_density_per_unit", 30) ... 1.3.3. 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. Example 1.3. Set remove_latency parameter ... modparam("pike", "remove_latency", 130) ... 1.3.4. 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). Example 1.4. Set pike_log_level parameter ... modparam("pike", "pike_log_level", -1) ... 1.4. Exported Functions 1.4.1. 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 occured. Warning 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. Example 1.5. pike_check_req usage ... if (!pike_check_req()) { exit; }; ... 1.5. Exported MI Functions 1.5.1. pike_list Lists the nodes in the pike tree. Name: pike_list Parameters: none MI FIFO Command Format: :pike_list:_reply_fifo_file_ _empty_line_ Chapter 2. 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. Example 2.1. 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 and hits). For 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, 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.