OpenSSH

Blackbox Asset Management: Discovering and Identifying IT Infrastructure Without Direct Access

Security Vision expert Fedor Bokov explains how organizations can manage IT assets in blackbox mode when customers refuse to provide credentials or internal documentation. The approach begins with network scanning using tools such as nmap and masscan to detect live hosts and open ports across external and internal perimeters. Identification relies on banner grabbing, HTTP header analysis, favicon inspection, HTML structure, and service fingerprinting to determine exact software versions and operating systems. Examples include extracting Ubuntu 22.04 LTS details from an OpenSSH banner and identifying Checkpoint Gaia from specific HTTP responses on port 443. Further analysis of ports like 1433 and 443 reveals Microsoft SQL Server 2017, nginx 1.28.0, PHP 8.2.29, and Bitrix-Site-Manager instances. The methodology concludes with continuous monitoring cycles that track version changes, new services, and configuration deviations to prioritize vulnerability remediation without traditional inventory access.

Developer Builds Custom Bouncer Tool to Automatically Block .env and SSH Probing on VPS

A system administrator running a small VPS with Caddy and static sites grew tired of constant password guessing attempts against SSH and repeated probes for files like .env, wp-admin, and config.php.bak. Instead of relying on Fail2ban, which required complex jail and filter configuration, the admin created a lightweight Rust-based tool named Bouncer. The program first crawls the site to build a list of legitimate paths, then monitors access logs and systemd journal entries for SSH invalid user attempts. IPs that generate multiple 404 responses for unknown paths or trigger SSH invalid user messages are added to an nftables set for automatic blocking. Special immediate bans are applied for direct hits on sensitive files such as /.env. The tool avoids double-counting SSH log lines, skips historical log replay on startup, and integrates directly with existing nftables rules without requiring additional runtime dependencies.