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cisco-asa-syslog

Parse, interpret, and analyze Cisco ASA (Adaptive Security Appliance) firewall syslog messages. Use this skill whenever working with Cisco ASA log files, syslog streams from ASA devices, firewall event analysis, or security investigations involving ASA-generated events. Covers the syslog protocol foundation and the ASA-specific message format with message ID categorization.

skill-install — Terminal

Install via CLI (Recommended)

clawhub install openclaw/skills/skills/gangtao/cisco-asa-syslog
Or

Cisco ASA Syslog Analysis

This skill teaches you how to read, parse, and interpret log messages generated by Cisco ASA firewalls. All ASA logs are delivered via the syslog protocol, so understanding syslog is foundational before working with ASA-specific content.


Part 1: Syslog Protocol Foundation

All Cisco ASA log messages are transported and formatted using the syslog standard (RFC 3164 / RFC 5424). You must understand syslog before interpreting ASA messages.

Severity Levels

Every syslog message carries a numeric severity (0 = most critical, 7 = least critical):

LevelKeywordMeaning
0EmergencySystem is unusable
1AlertImmediate action required
2CriticalCritical conditions
3ErrorError conditions
4WarningWarning conditions
5NoticeNormal but significant events
6InformationalRoutine informational messages
7DebugVerbose diagnostic output

Facility Codes

Facility codes indicate the source subsystem (0-23). Cisco ASA uses local4 (code 20) by default, but this is configurable on the device.

PRI Value

The PRI header encodes both facility and severity:

PRI = (Facility x 8) + Severity

Example: local4 (20) + Informational (6) -> (20 x 8) + 6 = 166, shown as <166> in the log header. This is the most common PRI value seen in ASA logs.

RFC 3164 Format (Traditional)

<PRI>TIMESTAMP HOSTNAME TAG: MESSAGE

Example: <166>Jan 15 10:22:01 fw01 : %ASA-6-302013: Built outbound TCP connection...

RFC 5424 Format (ASA 9.10+)

Enabled via "logging timestamp rfc5424". Uses ISO 8601 UTC timestamps:

<PRI>VERSION TIMESTAMP HOSTNAME APP-NAME PROCID MSGID STRUCTURED-DATA MSG

Example: <166>1 2018-06-27T12:17:46Z asa - - - %ASA-6-110002: Failed to locate egress interface...


Part 2: Cisco ASA Log Format

Core Message Structure

Every ASA event message follows this pattern, regardless of syslog envelope:

%ASA-severity-message_id: message_text

FieldDescription
%ASAFixed literal prefix on all ASA messages
severitySingle digit 0-7 matching syslog severity levels above
message_id6-digit numeric ID uniquely identifying the event type
message_textHuman-readable description with variable substitutions

Full Log Line with Syslog Envelope

<PRI> TIMESTAMP HOSTNAME : %ASA-severity-message_id: message_text

Metadata

Author@gangtao
Stars2387
Views0
Updated2026-03-09
View Author Profile
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Add to Configuration

Paste this into your clawhub.json to enable this plugin.

{
  "plugins": {
    "official-gangtao-cisco-asa-syslog": {
      "enabled": true,
      "auto_update": true
    }
  }
}
Safety NoteClawKit audits metadata but not runtime behavior. Use with caution.