Tag: networking

Incomplete cert chains, wrong order, self-signed certs. How to diagnose trust failures with openssl s_client.

Firewall rules are evaluated top-down, first match wins. One misplaced ALLOW rule above your denials silently defeats all your security. Here's the fix.

Verify fail2ban is protecting you: check jails, test bans, monitor logs, common misconfiguration, and unban IPs when needed.

SSHFS mounts remote filesystems over SSH so you can browse and edit files locally, faster than scp for interactive work.

Fix SSH timeouts: ServerAliveInterval, ServerAliveCountMax, ClientAliveInterval. Understand NAT, firewalls, and TCP keepalive.

ss replaces netstat on modern Linux: faster, shows more socket detail, and reads from the kernel. Every netstat command you rely on, rewritten for ss.

Network aliases give containers multiple DNS names. Perfect for blue-green deploys and service discovery patterns.

Master lsof to find port conflicts, trace deleted files eating disk, and debug network connections.

Something's squatting on port 8080 and you need to know what. ss, netstat, and lsof one-liners to find the PID behind a port fast.

AV vs EDR, traditional antivirus signatures vs behavioral endpoint detection. What each catches, what it misses, and what you actually need.

Certificate pinning locks your app to a specific TLS cert so MITM attackers can't swap in a rogue CA, how it works and when to use it.

Bridge, host, overlay, macvlan, and none, every Docker network mode explained with real use cases from beginner to production.