Use this documentation with care! It describes the outdated version 7, which was actively developed around 2014 and is considered dead by the rsyslog team.

This documentation reflects the latest update of the v7-stable branch. It describes the 7.6.8 version, which was never released. As such, it contains some content that does not apply to any released version.

To obtain the doc that properly matches your installed v7 version, obtain the doc set from your distro. Each version of rsyslog contained the version that exactly matches it.

As general advise, it is strongly suggested to upgrade to the current version supported by the rsyslog project. The current version can always be found on the right-hand side info box on the rsyslog web site.

Note that there is only limited rsyslog community support available for the outdated v7 version (officially we do not support it at all, but we usually are able to answer simple questions). If you need to stick with v7, it probably is best to ask your distribution for support.

imtcp: TCP Syslog Input Module

Provides the ability to receive syslog messages via TCP. Encryption is natively provided by selecting the approprioate network stream driver and can also be provided by using stunnel (an alternative is the use the imgssapi module).

Author:Rainer Gerhards <rgerhards@adiscon.com>

Configuration Parameters

Global Parameters

AddtlFrameDelimiter <Delimiter>

This directive permits to specify an additional frame delimiter for Multiple receivers may be configured by specifying $InputTCPServerRun multiple times. This is available since version 4.3.1, earlier versions do NOT support it.

DisableLFDelimiter on/off

Default is off

Industry-strandard plain text tcp syslog uses the LF to delimit syslog frames. However, some users brought up the case that it may be useful to define a different delimiter and totally disable LF as a delimiter (the use case named were multi-line messages). This mode is non-standard and will probably come with a lot of problems. However, as there is need for it and it is relatively easy to support, we do so. Be sure to turn this setting to “on” only if you exactly know what you are doing. You may run into all sorts of troubles, so be prepared to wrangle with that!

NotifyOnConnectionClose on/off

Default is off

Instructs imtcp to emit a message if the remote peer closes a connection.

Important: This directive is global to all listeners and must be given right after loading imtcp, otherwise it may have no effect.

KeepAlive on/off

Default is off

enable of disable keep-alive packets at the tcp socket layer. The default is to disable them.

FlowControl on/off

Default is on

This setting specifies whether some message flow control shall be exercised on the related TCP input. If set to on, messages are handled as “light delayable”, which means the sender is throttled a bit when the queue becomes near-full. This is done in order to preserve some queue space for inputs that can not throttle (like UDP), but it may have some undesired effect in some configurations. Still, we consider this as a useful setting and thus it is the default. To turn the handling off, simply configure that explicitely.

MaxListeners <number>

Default is 20

Sets the maximum number of listeners (server ports) supported. This must be set before the first $InputTCPServerRun directive.

MaxSessions <number>

Default is 200

Sets the maximum number of sessions supported. This must be set before the first $InputTCPServerRun directive

StreamDriver.Mode <number>

Sets the driver mode for the currently selected network stream driver. <number> is driver specific.

StreamDriver.AuthMode <mode-string>

Sets permitted peer IDs. Only these peers are able to connect to the listener. <id-string> semantics depend on the currently selected AuthMode and  network stream driver. PermittedPeers may not be set in anonymous modes.

PermittedPeer <id-string>

Sets permitted peer IDs. Only these peers are able to connect to the listener. <id-string> semantics depend on the currently selected AuthMode and  network stream driver. PermittedPeer may not be set in anonymous modes. PermittedPeer may be set either to a single peer or an array of peers either of type IP or name, depending on the tls certificate.

Single peer: PermittedPeer=”127.0.0.1”

Array of peers: PermittedPeer=[“test1.example.net”,”10.1.2.3”,”test2.example.net”,”…”]

Action Parameters

Port <port>

Starts a TCP server on selected port

Name <name>

Sets a name for the inputname property. If no name is set “imtcp” is used by default. Setting a name is not strictly necessary, but can be useful to apply filtering based on which input the message was received from.

Ruleset <ruleset>

Binds the listener to a specific ruleset.

SupportOctetCountedFraming on/off

Default is on

If set to “on”, the legacy octed-counted framing (similar to RFC5425 framing) is activated. This should be left unchanged until you know very well what you do. It may be useful to turn it off, if you know this framing is not used and some senders emit multi-line messages into the message stream.

RateLimit.Interval [number]

Specifies the rate-limiting interval in seconds. Default value is 0, which turns off rate limiting. Set it to a number of seconds (5 recommended) to activate rate-limiting.

RateLimit.Burst [number]

Specifies the rate-limiting burst in number of messages. Default is 10,000.

Caveats/Known Bugs

  • module always binds to all interfaces
  • can not be loaded together with imgssapi (which includes the functionality of imtcp)

See also

Example

This sets up a TCP server on port 514 and permits it to accept up to 500 connections:

module(load="imtcp" MaxSessions="500")
input(type="imtcp" port="514")

Note that the global parameters (here: max sessions) need to be set when the module is loaded. Otherwise, the parameters will not apply.

Legacy Configuration Directives

$InputTCPServerAddtlFrameDelimiter <Delimiter>

equivalent to: AddtlFrameDelimiter

$InputTCPServerDisableLFDelimiter on/off

equivalent to: DisableLFDelimiter

$InputTCPServerNotifyOnConnectionClose on/off

equivalent to: NotifyOnConnectionClose

$InputTCPServerKeepAlive** <on/**off**>

equivalent to: KeepAlive

$InputTCPServerRun <port>

equivalent to: Port

$InputTCPFlowControl on/off

equivalent to: FlowControl

$InputTCPMaxListeners <number>

equivalent to: MaxListeners

$InputTCPMaxSessions <number>

equivalent to: MaxSessions

$InputTCPServerStreamDriverMode <number>

equivalent to: StreamDriver.Mode

$InputTCPServerInputName <name>

equivalent to: Name

$InputTCPServerStreamDriverAuthMode <mode-string>

equivalent to: StreamDriver.AuthMode

$InputTCPServerStreamDriverPermittedPeer <id-string>

equivalent to: PermittedPeer.

$InputTCPServerBindRuleset <ruleset>

equivalent to: Ruleset.

$InputTCPSupportOctetCountedFraming on/off

equivalent to: SupportOctetCountedFraming

Caveats/Known Bugs

  • module always binds to all interfaces
  • can not be loaded together with imgssapi (which includes the functionality of imtcp)

Example

This sets up a TCP server on port 514 and permits it to accept up to 500 connections:

$ModLoad imtcp # needs to be done just once
$InputTCPMaxSessions 500
$InputTCPServerRun 514

Note that the parameters (here: max sessions) need to be set before the listener is activated. Otherwise, the parameters will not apply.