Projects

SSH Auth Failure Log Analyzer

Built a lightweight security monitoring tool to analyze real SSH authentication failures on a Linux system using Windows Subsystem for Linux (WSL).

What I Did

• Parsed SSH authentication logs from /var/log/auth.log
• Wrote a Python script to detect failed SSH attempts and pre-authentication disconnects
• Grouped failures by source IP address and targeted username
• Identified patterns consistent with brute-force attacks
• Generated a readable summary report for quick review

Validation & Testing

• Generated controlled failed SSH login attempts using invalid usernames
• Verified failures appeared in system authentication logs
• Confirmed the analyzer correctly counted and categorized events
• Re-ran analysis after additional attempts to ensure results updated dynamically
• Validated regex matching against multiple SSH failure message formats

Tools

Python • Ubuntu Linux (WSL) • OpenSSH • Linux authentication logs

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SSH Hardening

Hardened SSH on an Ubuntu server to improve security while keeping remote access reliable.

What I Did

• Moved SSH to a non-standard port (2222)
• Disabled password-based logins and prevented direct root access
• Limited SSH to modern, secure cryptographic algorithms
• Fixed SSH file permissions (.ssh and authorized_keys)
• Set up persistent firewall rules using iptables-persistent

Validation & Testing

• Checked the active SSH configuration with sshd -T
• Verified which ports SSH was listening on using ss
• Used verbose SSH output to troubleshoot connection issues
• Learned and accounted for NAT loopback limitations when testing from the same machine
• Confirmed external access by testing from a separate network

Tools

OpenSSH • Ubuntu Linux • iptables / netfilter-persistent • systemd • ssh-audit