Splunk® Enterprise

Add Cisco ASA data: Single instance

Splunk Enterprise version 7.2 is no longer supported as of April 30, 2021. See the Splunk Software Support Policy for details. For information about upgrading to a supported version, see How to upgrade Splunk Enterprise.
This documentation does not apply to the most recent version of Splunk® Enterprise. For documentation on the most recent version, go to the latest release.

Install a syslog-ng server

To get data into your single-instance Splunk Enterprise deployment, configure a Linux-based syslog server to send your Cisco Adaptive Security Appliance (ASA) deployment-related syslog messages.

Determine the size of your Cisco ASA logs

Each firewall message is approximately 230 bytes, and users typically see one message per connection. As a best practice, use logging-allowed connections and denied connections. The log volume depends on the size of your ASA device.

Using only Cisco’s built-in tools, use the show ip inspect statistics command to see how many connections occur since your last reset.

The following table shows approximate sizes of logs per type of service:

Service Approximate size of log
Edge Firewall Negligible
Zone Firewall 230 bytes per event
VPN Services 10 Kb per session + firewall activity
Operational Approximately <200 MB per day per ASA


Install a syslog-ng server

To install a syslog-ng server, complete the following steps:

  1. (Optional) Uninstall rsyslog if it shipped with your deployment:
    sudo rpm -e --nodeps rsyslog
  2. Install syslog-ng using yum: sudo yum-get install syslog-ng
  3. Configure yum to search the EPEL repo:
    sudo yum --enablerepo=epel install syslog-ng
  4. (Optional) Install the syslog-ng-libdbi module to prevent a warning message from appearing each time syslog-ng starts:
    sudo yum install --enablerepo=epel syslog-ng-libdbi
  5. Once you complete the installation, start syslog-ng: 
    sudo systemctl start syslog-ng.service
sudo systemctl enable syslog-ng.service
  6. Verify that syslog-ng is running by checking for a pid:
    pidof syslog-ng
Last modified on 24 August, 2020
Introduction   Install a universal forwarder on the same host as the syslog-ng server

This documentation applies to the following versions of Splunk® Enterprise: 7.2.0, 7.2.1, 7.2.2, 7.2.3, 7.2.4, 7.2.5, 7.2.6, 7.2.7, 7.2.8, 7.2.9, 7.2.10, 7.3.0, 7.3.1, 7.3.2, 7.3.3, 7.3.4, 7.3.5, 7.3.6, 7.3.7, 7.3.8, 7.3.9, 8.0.0, 8.0.1, 8.0.2, 8.0.3, 8.0.4, 8.0.5, 8.0.6, 8.0.7, 8.0.8, 8.0.9, 8.0.10

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