# Log Sources [![[Pasted image 20251104230233.png]]](https://soc-expert.de/From+Logging+to+Alerting+and+Beyond) Log data is generated by various systems such as: - Servers - Applications - Network devices - Security tools - Cloud services ## Log Entry vs Event vs Alert These terms are often used interchangeably, but they refer to **different layers** of log management and SIEM operations. ### Log Source - **Definition**: The origin or system that generates log data. - **Examples**: - Firewalls - Web servers - Operating systems (Windows/Linux) - Applications (e.g., Apache, MySQL) - Cloud services (e.g., AWS CloudTrail) - **Role**: Provides raw data for monitoring and analysis. ### Log (or Log File) - **Definition**: A file or stream that contains a collection of log entries. - **Examples**: - `/var/log/syslog` (Linux system logs) - `eventlog.evtx` (Windows Event Logs) - `access.log` (Web server access logs) - **Role**: Stores logs in a readable or structured format for later retrieval. ### Log Entry - **Definition**: A single line or record within a log file that describes an event or action. - **Examples**: - `Nov 4 20:01:23 server1 sshd[1234]: Accepted password for user1 from 192.168.1.10` - `{"timestamp":"2025-11-04T20:01:23Z","event":"login","user":"user1","ip":"192.168.1.10"}` - **Role**: Represents a discrete action or status update from the system. ### Event - **Definition**: A meaningful occurrence derived from one or more log entries. - **Examples**: - A successful login - A failed authentication attempt - A file being accessed or modified - **Role**: Used by SIEMs to correlate and analyze behavior across systems. >[!note] **Note**: In SIEMs, events are often **normalized** and **categorized** to enable correlation and rule-based detection. ### Alert - **Definition**: A notification triggered by a rule or threshold when specific events or patterns are detected. - **Examples**: - 10 failed login attempts within 1 minute → **Brute-force attack alert** - Access to sensitive files outside business hours → **Suspicious activity alert** - **Role**: Drives incident response and security monitoring. ## Summary Table |Term|What It Is|Example|Role in SIEM| |---|---|---|---| |**Log Source**|Origin of logs|Firewall, Server, App|Data provider| |**Log File**|Container for log entries|`/var/log/auth.log`|Storage| |**Log Entry**|Single record in a log|`User login from IP 1.2.3.4`|Raw data| |**Event**|Parsed/normalized action|`Login success`|Analysis| |**Alert**|Triggered notification|`Multiple failed logins`|Response| ---