SC4S Destination Configuration¶

Splunk Connect for Syslog can be configured to utilize any destination available in syslog-ng OSE. The configuration system provides ease of use helpers to manage configuration for the three most common destination needs, Splunk HEC, RFC5424 Syslog, and Legacy BSD Syslog.

In the getting started guide you configured the Splunk HEC “DEFAULT” destination to receive all traffic by default. The “DEFAULT” destination should be configured to accept all events to ensure that at least one destination has the event to avoid data loss due to misconfiguration. The following example demonstrates configuration of a second HEC destination where only “selected” data will be sent.

Example 1 Send all events¶

#Note "OTHER" should be a meaningful name
SC4S_DEST_SPLUNK_HEC_OTHER_URL=https://splunk:8088
SC4S_DEST_SPLUNK_HEC_OTHER_TOKEN=${SPLUNK_HEC_TOKEN}
SC4S_DEST_SPLUNK_HEC_OTHER_TLS_VERIFY=no
SC4S_DEST_SPLUNK_HEC_OTHER_MODE=GLOBAL

Example 2 Send only cisco IOS Events¶

#Note "OTHER" should be a meaningful name
SC4S_DEST_SPLUNK_HEC_OTHER_URL=https://splunk:8088
SC4S_DEST_SPLUNK_HEC_OTHER_TOKEN=${SPLUNK_HEC_TOKEN}
SC4S_DEST_SPLUNK_HEC_OTHER_TLS_VERIFY=no
SC4S_DEST_SPLUNK_HEC_OTHER_MODE=SELECT
SC4S_DEST_CISCO_IOS_ALTERNATES=d_fmt_hec_OTHER

Example 3 Send only cisco IOS events that are not debug¶

#Note "OTHER" should be a meaningful name
SC4S_DEST_SPLUNK_HEC_OTHER_URL=https://splunk:8088
SC4S_DEST_SPLUNK_HEC_OTHER_TOKEN=${SPLUNK_HEC_TOKEN}
SC4S_DEST_SPLUNK_HEC_OTHER_TLS_VERIFY=no
SC4S_DEST_SPLUNK_HEC_OTHER_MODE=SELECT

#filename:
application sc4s-lp-cisco_ios_dest_fmt_other{{ source }}[sc4s-lp-dest-select-d_fmt_hec_OTHER] {
    filter {
        'CISCO_IOS' eq "${fields.sc4s_vendor}_${fields.sc4s_product}"
        #Match any cisco event that is not like "%ACL-7-1234"
        and not message('^%[^\-]+-7-');
    };    
};

Supported Simple Destination configurations¶

SC4S Supports the following destination configurations via configuration. Any custom destination can be supported (defined by syslog-ng OSE)

Splunk HTTP Event Collector (HEC)
RFC5424 format without frames i.e. <166>1 2022-02-02T14:59:55.000+00:00 kinetic-charlie - - - - %FTD-6-430003: DeviceUUID:
RFC5424 format with frames also known as RFC6587 123 <166>1 2022-02-02T14:59:55.000+00:00 kinetic-charlie - - - - %FTD-6-430003: DeviceUUID:
RFC3164 (BSD format) <134>Feb 2 13:43:05.000 horse-ammonia CheckPoint[26203]:

HEC Destination Configuration¶

Variable	Values	Description
SC4S_DEST_SPLUNK_HEC_<ID>_URL	url	URL(s) of the Splunk endpoint, can be a single URL space separated list
SC4S_DEST_SPLUNK_HEC_<ID>_TOKEN	string	Splunk HTTP Event Collector Token
SC4S_DEST_SPLUNK_HEC_<ID>_MODE	string	“GLOBAL” or “SELECT”
SC4S_DEST_SPLUNK_HEC_DEFAULT_TLS_VERIFY	yes(default) or no	verify HTTP(s) certificate

Syslog Standard destination.¶

Note: in many cases destinations incorrectly assert “syslog” support. IETF standards RFC5424, RFC5425, RFC6587 define the use of “syslog” as a network protocol. Often the actual configuration required is Legacy BSD syslog which is NOT a standard and was documented “historically” in RFC3164 see BSD Destination section.

Variable	Values	Description
SC4S_DEST_SYSLOG_<ID>_HOST	fqdn or ip	the FQDN or IP of the target
SC4S_DEST_SYSLOG_<ID>_PORT	number	601 (default when framed) 514 (default when not framed)
SC4S_DEST_SYSLOG_<ID>_IETF	yes,no	default “yes” use IETF Standard frames
SC4S_DEST_SYSLOG_<ID>_MODE	string	“GLOBAL” or “SELECT”

BSD legacy destination (Non standard)¶

Note: in many cases destinations incorrectly assert “syslog” support. IETF standards RFC5424, RFC5425, RFC6587 define the use of “syslog” as a network protocol. Often the actual configuration required is Legacy BSD syslog which is NOT a standard and was documented “historically” in RFC3164 see BSD Destination section.

Variable	Values	Description
SC4S_DEST_BSD_<ID>_HOST	fqdn or ip	the FQDN or IP of the target
SC4S_DEST_BSD_<ID>_PORT	number	default 514
SC4S_DEST_BSD_<ID>_TRANSPORT	tcp,udp,tls	default tcp
SC4S_DEST_BSD_<ID>_MODE	string	“GLOBAL” or “SELECT”

Configuration of Alternate Destinations¶

In addition to the standard HEC destination that is used to send events to Splunk, alternate destinations can be created and configured in SC4S. All alternate destinations (including alternate HEC destinations discussed below) are configured using the environment variables below. Global and/or source-specific forms of the variables below can be used to send data to additional and/or alternate destinations.

NOTE: The administrator is responsible for ensuring that any non-HEC alternate destinations are configured in the local mount tree, and that the underlying syslog-ng process in SC4S properly parses them.
NOTE: Do not include the primary HEC destination (d_fmt_hec) in any list of alternate destinations. The configuration of the primary HEC destination is configured separately from that of the alternates below. However, alternate HEC destinations (e.g. d_fmt_hec_FOO) should be configured below, just like any other user-supplied destination.

Variable	Values	Description
SC4S_DEST_<VENDOR_PRODUCT>_ALTERNATES	Comma or space-separated list of syslog-ng destinations	Send specific sources to alternate syslog-ng destinations using the VENDOR_PRODUCT syntax, e.g. `SC4S_DEST_CISCO_ASA_ALTERNATES=d_syslog_foo`

Configuration of Filtered Alternate Destinations (Advanced)¶

Though source-specific forms of the variables configured above will limit configured alternate destinations to a specific data source, there are cases where even more granularity is desired within a specific data source (e.g. to send all Cisco ASA “debug” traffic to Cisco Prime for analysis). This extra traffic may or may not be needed in Splunk. To accommodate this use case, Filtered Alternate Destinations allow a filter to be supplied to redirect a portion of a given source’s traffic to a list of alternate destinations (and, optionally, to prevent matching events from being sent to Splunk). Again, these are configured through environment variables similar to the ones above:

Variable	Values	Description
SC4S_DEST_<VENDOR_PRODUCT>_ALT_FILTER	syslog-ng filter	Filter to determine which events are sent to alternate destination(s)
SC4S_DEST_<VENDOR_PRODUCT>_FILTERED_ALTERNATES	Comma or space-separated list of syslog-ng destinations	Send filtered events to alternate syslog-ng destinations using the VENDOR_PRODUCT syntax, e.g. `SC4S_DEST_CISCO_ASA_FILTERED_ALTERNATES`

NOTE: This is an advanced capability, and filters and destinations using proper syslog-ng syntax must be constructed prior to utilizing this feature.
NOTE: Unlike the standard alternate destinations configured above, the regular “mainline” destinations (including the primary HEC destination or configured archive destination (d_hec or d_archive)) are not included for events matching the configured alternate destination filter. If an event matches the filter, the list of filtered alternate destinations completely replaces any mainline destinations including defaults and global or source-based standard alternate destinations. Be sure to include them in the filtered destination list if desired.
HINT: Since the filtered alternate destinations completely replace the mainline destinations (including HEC to Splunk), a filter that matches all traffic can be used with a destination list that does not include the standard HEC destination to effectively turn off HEC for a given data source.