policy/frameworks/netcontrol/catch-and-release.zeek

NetControl

Implementation of catch-and-release functionality for NetControl.

Namespace

NetControl

Imports

base/frameworks/cluster, base/frameworks/netcontrol

Summary

Runtime Options

NetControl::catch_release_warn_blocked_ip_encountered: bool &redef

If true, catch and release warns if packets of an IP address are still seen after it should have been blocked.

Redefinable Options

NetControl::catch_release_intervals: vector &redef

Time intervals for which subsequent drops of the same IP take effect.

NetControl::watch_connections: bool &redef

If true, catch_release_seen is called on the connection originator in new_connection, connection_established, partial_connection, connection_attempt, connection_rejected, connection_reset and connection_pending

Types

NetControl::BlockInfo: record

This record is used for storing information about current blocks that are part of catch and release.

NetControl::CatchReleaseActions: enum

The enum that contains the different kinds of messages that are logged by catch and release.

NetControl::CatchReleaseInfo: record

The record type that is used for representing and logging

Redefinitions

Log::ID: enum

Events

NetControl::catch_release_add: event

NetControl::catch_release_block_delete: event

NetControl::catch_release_block_new: event

NetControl::catch_release_delete: event

NetControl::catch_release_encountered: event

NetControl::catch_release_forgotten: event

Event is raised when catch and release cases management of an IP address because no activity was seen within the watch_until period.

NetControl::log_netcontrol_catch_release: event

Event that can be handled to access the NetControl::CatchReleaseInfo record as it is sent on to the logging framework.

Hooks

NetControl::log_policy_catch_release: Log::PolicyHook

Functions

NetControl::catch_release_seen: function

This function can be called to notify the catch and release script that activity by an IP address was seen.

NetControl::drop_address_catch_release: function

Stops all packets involving an IP address from being forwarded.

NetControl::get_catch_release_info: function

Get the NetControl::BlockInfo record for an address currently blocked by catch and release.

NetControl::unblock_address_catch_release: function

Removes an address from being watched with catch and release.

Detailed Interface

Runtime Options

NetControl::catch_release_warn_blocked_ip_encountered
Type

bool

Attributes

&redef

Default

F

If true, catch and release warns if packets of an IP address are still seen after it should have been blocked.

Redefinable Options

NetControl::catch_release_intervals
Type

vector of interval

Attributes

&redef

Default
[10.0 mins, 1.0 hr, 1.0 day, 7.0 days]

Time intervals for which subsequent drops of the same IP take effect.

NetControl::watch_connections
Type

bool

Attributes

&redef

Default

T

If true, catch_release_seen is called on the connection originator in new_connection, connection_established, partial_connection, connection_attempt, connection_rejected, connection_reset and connection_pending

Types

NetControl::BlockInfo
Type

record

block_until: time &optional

Absolute time indicating until when a block is inserted using NetControl.

watch_until: time

Absolute time indicating until when an IP address is watched to reblock it.

num_reblocked: count &default = 0 &optional

Number of times an IP address was reblocked.

current_interval: count

Number indicating at which catch and release interval we currently are.

current_block_id: string

ID of the inserted block, if any.

location: string &optional

User specified string.

This record is used for storing information about current blocks that are part of catch and release.

NetControl::CatchReleaseActions
Type

enum

NetControl::INFO

Log lines marked with info are purely informational; no action was taken.

NetControl::ADDED

A rule for the specified IP address already existed in NetControl (outside of catch-and-release). Catch and release did not add a new rule, but is now watching the IP address and will add a new rule after the current rule expires.

NetControl::DROP_REQUESTED

A drop was requested by catch and release.

NetControl::DROPPED

An address was successfully blocked by catch and release.

NetControl::UNBLOCK

An address was unblocked after the timeout expired.

NetControl::FORGOTTEN

An address was forgotten because it did not reappear within the watch_until interval.

NetControl::SEEN_AGAIN

A watched IP address was seen again; catch and release will re-block it.

The enum that contains the different kinds of messages that are logged by catch and release.

NetControl::CatchReleaseInfo
Type

record

ts: time &log

The absolute time indicating when the action for this log-line occurred.

rule_id: string &log &optional

The rule id that this log line refers to.

ip: addr &log

The IP address that this line refers to.

action: NetControl::CatchReleaseActions &log

The action that was taken in this log-line.

block_interval: interval &log &optional

The current block_interval (for how long the address is blocked).

watch_interval: interval &log &optional

The current watch_interval (for how long the address will be watched and re-block if it reappears).

blocked_until: time &log &optional

The absolute time until which the address is blocked.

watched_until: time &log &optional

The absolute time until which the address will be monitored.

num_blocked: count &log &optional

Number of times that this address was blocked in the current cycle.

location: string &log &optional

The user specified location string.

message: string &log &optional

Additional informational string by the catch and release framework about this log-line.

The record type that is used for representing and logging

Events

NetControl::catch_release_add
Type

event (a: addr, location: string)

NetControl::catch_release_block_delete
Type

event (a: addr)

NetControl::catch_release_block_new
Type

event (a: addr, b: NetControl::BlockInfo)

NetControl::catch_release_delete
Type

event (a: addr, reason: string)

NetControl::catch_release_encountered
Type

event (a: addr)

NetControl::catch_release_forgotten
Type

event (a: addr, bi: NetControl::BlockInfo)

Event is raised when catch and release cases management of an IP address because no activity was seen within the watch_until period.

Parameters
  • a – The address that is no longer being managed.

  • bi – The NetControl::BlockInfo record containing information about the block.

NetControl::log_netcontrol_catch_release
Type

event (rec: NetControl::CatchReleaseInfo)

Event that can be handled to access the NetControl::CatchReleaseInfo record as it is sent on to the logging framework.

Hooks

NetControl::log_policy_catch_release
Type

Log::PolicyHook

Functions

NetControl::catch_release_seen
Type

function (a: addr) : void

This function can be called to notify the catch and release script that activity by an IP address was seen. If the respective IP address is currently monitored by catch and release and not blocked, the block will be reinstated. See the documentation of watch_new_connection which events the catch and release functionality usually monitors for activity.

Parameters

a – The address that was seen and should be re-dropped if it is being watched.

NetControl::drop_address_catch_release
Type

function (a: addr, location: string &default = "" &optional) : NetControl::BlockInfo

Stops all packets involving an IP address from being forwarded. This function uses catch-and-release functionality, where the IP address is only dropped for a short amount of time that is incremented steadily when the IP is encountered again.

In cluster mode, this function works on workers as well as the manager. On managers, the returned NetControl::BlockInfo record will not contain the block ID, which will be assigned on the manager.

Parameters
  • a – The address to be dropped.

  • t – How long to drop it, with 0 being indefinitely.

  • location – An optional string describing where the drop was triggered.

Returns

The NetControl::BlockInfo record containing information about the inserted block.

NetControl::get_catch_release_info
Type

function (a: addr) : NetControl::BlockInfo

Get the NetControl::BlockInfo record for an address currently blocked by catch and release. If the address is unknown to catch and release, the watch_until time will be set to 0.

In cluster mode, this function works on the manager and workers. On workers, the data will lag slightly behind the manager; if you add a block, it will not be instantly available via this function.

Parameters

a – The address to get information about.

Returns

The NetControl::BlockInfo record containing information about the inserted block.

NetControl::unblock_address_catch_release
Type

function (a: addr, reason: string &default = "" &optional) : bool

Removes an address from being watched with catch and release. Returns true if the address was found and removed; returns false if it was unknown to catch and release.

If the address is currently blocked, and the block was inserted by catch and release, the block is removed.

Parameters
  • a – The address to be unblocked.

  • reason – A reason for the unblock.

Returns

True if the address was unblocked.