Splunk Stream

Installation and Configuration Manual

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Configure Stream forwarder

About Stream forwarder configuration

There are two types of configuration that apply to Stream forwarder:

  • Streams Config UI: The Streams Config UI lets you select and configure the specific wire data protocols that you want streamfwd to capture. You can access the Streams UI inside the Splunk App for Stream product using Splunk Web. See Configure Streams.
  • streamfwd.xml: The streamfwd.xml configuration file lets you specify system-level data capture parameters for the streamfwd binary. You can access streamfwd.xml from the command line at $SPLUNK_HOME/etc/apps/Splunk_TA_stream/default/streamfwd.xml.

Note: If you want to edit streamfwd.xml, you must copy the entire file to Splunk_TA_stream/local and make your changes to the copy of streamfwd.xml in Splunk_TA_stream/local. See Configure streamfwd.xml.

Verify streamfwd can communicate with splunk_app_stream

Before you configure data capture parameters for the streamfwd binary using the Stream Config UI, make sure that the streamfwd binary is configured to communicate with splunk_app_stream. To do so, confirm that the local inputs.conf file for Splunk_TA_stream contains the correct location of your splunk_app_stream installation.

1. Open $SPLUNK_HOME/etc/apps/Splunk_TA_stream/local/inputs.conf.

2. Confirm that the [streamfwd://streamfwd] stanza contains the correct location (URI) of your splunk_app_stream installation.

For example:

splunk_stream_app_location = https://localhost:8000/en-us/custom/splunk_app_stream/
disabled = 0

Specify the location of splunk_app_stream

You specify the location (URI) of your splunk_app_stream installation when you create a Wire Data modular input for your Stream data in Splunk Enterprise. The streamfwd binary uses this location to communicate with the splunk_app_stream over HTTP port 8000. splunk_app_stream stores the location that you specify in the local inputs.conf file of Splunk_TA_stream. See How streamfwd communicates with splunk_app_stream.

Note: The splunk_app_stream location URI supports http and https protocols only.

1. Go to Settings > Data Inputs > Wire Data.

2. Click New.

3. Enter a Name for your Wire Data modular input. For example "streamfwd."

4. Enter the URI (including the full path) to your splunk_app_stream installation. The URI must specify protocol, server, and port variables in the following syntax:


For example:


Note: If you enable SSL for the Stream forwarder, you must change the URI path to specify https. If you change the http port, you must change the URI path to specify the new port.

Note: If you want to use Splunk App for Stream with Splunk Enterprise deployments that include Splunk IT Service Intelligence (ITSI) and/or Splunk Enterprise Security (ES) (which have SSL enabled by default), you must use https when you specify the location of splunk_app_stream.

Configure streamfwd.xml

The streamfwd.xml configuration file lets you specify system-level parameters for the streamfwd binary. You can configure streamfwd.xml to listen on specific IP addresses and ports, enable SSL, redirect log files, collect network events, and specify network interfaces. streamfwd.xml also specifies default data extractions for HTTP protocol events.

streamfwd.xml is included with Splunk_TA_stream and is installed in:


Caution: Do not edit the streamfwd.xml file in the $SPLUNK_HOME/etc/apps/Splunk_TA_stream/default directory. This is a master copy of the configuration file. To edit the configuration, copy the streamfwd.xml to the $SPLUNK_HOME/etc/apps/Splunk_TA_stream/local directory and perform your edits there .

Basic configuration

streamfwd.xml is configured by default to listen for traffic on all available network interfaces.

<?xml version="1.0" encoding="UTF-8"?>
<CmConfig xmlns="http://purl.org/cloudmeter/config" version="6.0.0">

streamfwd.xmlaccepts these basic configuration parameters:

<IPAddr> IP address that the Stream Forwarder listens on
<Port> TCP port that the Stream Forwarder listens on (use "0" to disable)
<SSLKey> To enable SSL for the Stream Forwarder, specify a PEM-encoded RSA private key file
<User> Name of user the streamfwd process runs as
<Group> Name of group the streamfwd process runs as
<LogConfig> Configuration file to use for logging
<DataDirectory> Location of failover and other data files
<UIDirectory> Location of user interface files (do not change)
<DefaultVocabularyPath> Location of default vocabulary files (do not change)
<LocalVocabularyPath> Location of custom vocabulary files (do not change)

Advanced configuration

The streamfwd.xmlfile accepts these advanced configuration options.

Caution: Do not modify these options unless advised by your Splunk Support representative.

<MaxFieldSize> Maximum size of content field in bytes. Default is 10240. (version 6.2.0 and later only)
<ProcessingThreads> Number of threads to use for processing network traffic
<MaxPacketQueueSize> Maximum size for each processing threads' packet queue
<SessionKeyTimeout> Idle time in seconds before SSL session keys are expired
<TcpConnectionTimeout> Idle time in seconds before TCP/UDP flows are expired
<MaxTcpSessionCount> Maximum number of concurrent TCP/UDP flows
<MaxTcpReassemblyPacketCount> Maximum number of TCP packets in reassembly queue
<DuplicatePacketWindow> Set this to a value greater than zero to enable automatic de-duplication of network packets. The value indicates the number of packets cached in memory (using a rolling window) to detect duplicate packets.
<UseGlobalSSLSessionKeyCache> Set to "true" to share SSL cache across processing threads
<HideCreditCardNumbers> Set to "false" to disable the automatic masking of credit card numbers
<QueueEventDelivery> Set this to "true" to enable the use of a separate thread for the processing of captured events
<MapSslServers> Set this to "false" to disable automatic caching of encrypted versus unencrypted services
<ClientIpSslHashBytes> Number of Client IP octets to use for SSL processor thread hash algorithm (if global ssl session key cache is disabled)
<PingInterval> Use this option to modify the ping server interval (in seconds). The default ping server interval is 5 seconds.
<Protocol> Setting this to "http" will add support for more advanced content extraction, but only HTTP traffic
<MaxRequestContentLength> Max number of bytes extracted from HTTP request content (requires <Protocol>http</Protocol>)
<MaxResponseContentLength> Max number of bytes extracted from HTTP response content (requires <Protocol>http</Protocol>)
<RawRequestHeaders> Set to "true" to enable extraction of raw HTTP request headers (requires <Protocol>http</Protocol>)
<RawResponseHeaders> Set to "true" to enable extraction of raw HTTP response headers (requires <Protocol>http</Protocol>)
<AllowUtf8Conversion> Set to "true" to enable UTF8 conversion of HTTP request/response content (requires <Protocol>http</Protocol>)
<AllowSearchingContentForCharset> Set to "true" to enable searching of content for charset (requires <Protocol>http</Protocol>)

Disable Stream Forwarder admin interface

By default, the Stream Forwarder admin interface is enabled, listening on TCP port 8889. To disable the interface:

1. Go to $SPLUNK_HOME/etc/apps/Splunk_TA_stream/local.

2. Open the streamfwd.xml configuration file and change <Port>8889</Port> to <Port>0</Port>.

Use XML TcpServer element to specify TCP servers

Stream forwarder automatically detects the client and server endpoints when it captures the beginnings of TCP connections. If it starts capturing traffic after establishing a TCP connection, Stream forwarder normally assumes that the sender of the first packet it sees is the client.

You can modify this behavior by inserting <TcpServer> clauses that define the endpoints of specific TCP servers. If the sender of a packet matches the endpoint, Stream forwarder correctly categorizes it as a server response packet.


Example 1: Single HTTP server endpoint


Example 2: Wildcard endpoint


Use XML SSLServer element to specify SSL servers

Stream forwarder automatically detects whether endpoints are encrypted or not, and attempts to decrypt SSL sessions using the available private keys. Optionally, you can explicitly define the traffic as encrypted or decrypted by inserting <SSLServer> clauses:


Use XML Capture element to specify network interfaces

The Splunk Stream Forwarder configuration file (streamfwd.xml) is configured by default to listen for traffic on all available network interfaces. If you want to restrict data capture to specific network interfaces, you must insert an XML <Capture></Capture> clause that defines the network interfaces on which streamfwd.xml listens.

For example:

To specify a network interface on *nix:

    <Filter>tcp port 80</Filter>

To specify a network interface on Windows:

    <Filter>tcp port 80</Filter>

Note: On Windows, for <Interface> and <InterfaceRegex> nodes, you can substitute the interface name (such as "\Device\NPF_{D6995D00-B75C-48DB-99AA-69F0150126BC}") with the <Alias> or <Description> value, which is returned by the --iflist command line option. For example, <Interface>Local Area Connection 2</Interface> or <InterfaceRegex>Local Area.*</IntefaceRegex>. See List network interfaces on Windows and Linux.


Example 1: Configure streamfwd.xml to include local loopback capture

Stream Forwarder by default does not capture traffic that originates and terminates on the same machine. You can enable capture of this "local loopback" traffic using a Capture element in the configuration file:


The <InterfaceRegex> element instructs streamfwd.xml to expand and enumerate the interfaces that are actually available on the host machine, and dynamically generates internal configurations for each network interface that matches the regular expression.

Example 2: Configure streamfwd.xml for use across multiple systems

You might want to maintain a master copy of streamfwd.xml that you can reuse across multiple systems that have different network device names. The following streamfwd.xml configuration listens on all matching interfaces found.


Note that this configuration may generate startup warnings for any devices that do not support passive data capture.

Example 3: Capture data on specific network interfaces

In this example, on a system with 8 network interfaces, streamfwd.xml would listen only for tcp port 80 traffic on only two of those interfaces (4 and 5):

    <Filter>tcp port 80</Filter>

Example 4: Use pcap file instead of network interface

You can also use a previously generated pcap file instead of an actual network interface, using this variation of the <Capture> element.

    <Filter>tcp port 80</Filter>
<Interface> Should be set to the path of your pcap file
<Offline> True means use pcap, false means <Interface> is a network device name
<Repeat> True means to play back the pcap file repeatedly for continuous load
<SysTime> True means to use the system time for packet timestamps
<BitsPerSecond> Rate limiter, defaults to 10 Mbps if undefined and <Repeat> is true
Last modified on 19 October, 2015
Install Splunk App for Stream
Add SSL keys to use for decryption

This documentation applies to the following versions of Splunk Stream: 6.0.2, 6.1.0, 6.1.1, 6.2.0, 6.2.1, 6.2.2

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