Monitor logs for issues

Investigate and resolve the spike of ERROR entries in the auth log since 03:00. Tail /var/log/auth.log on app-auth-01 and follow related entries across app-auth-02 and the audit server, identify the source IPs triggering failures, block any brute-force IPs at the firewall, and summarize the root cause and mitigation for the incident report due to security by 09:00.

Before I hand the log bundle to the incident lead, make the problem readable. Pull the most frequent error messages, aggregate by source IP and user, surface the time window with the steepest growth, and flag entries that coincide with config changes so a reviewer can approve a containment plan quickly.

Since 03:00 auth logs show a surge of failed logins across three servers. I have timestamps and usernames but the source IPs are inconsistent and often private addresses. I don't know whether this is an internal scraper, compromised service, or forged entries in the audit pipeline. What's the likeliest diagnosis and the fastest trace to prove it?

Over months we spend hours chasing log noise—repeating parsing steps, resetting thresholds, and opening tickets that close when noise drops. We keep missing persistent causes like cron jobs or misconfigured monitors. What single change to our logging practice would cut repeated investigations by half and make true incidents stand out?