DevSecOps From First Principles in AWS #7 | Linux Networking : iptables, DNS, and Security Groups

00:00 Intro to Linux Networking 02:09 Network Interfaces Explained 04:49 Using the ip link Command 06:46 AWS Elastic Network Interfaces (ENI) 10:37 The Loopback Address (127.0.0.1) 14:47 WLAN vs Wired Cloud Networks 16:22 How Routing Tables Work 19:33 Incident: EC2 Internet Routing Failure 21:26 Persisting Network Configurations 24:58 Debugging with Ping and Traceroute 27:40 Incident: Stripe API Connection Timeout 30:35 Checking Open Ports with ss 32:27 Incident: ALB Health Check Failures 34:23 DNS Troubleshooting with dig 36:10 Incident: Stale Database DNS Entries 39:01 Debugging APIs using curl 41:31 Port Testing with telnet 42:42 Packet Sniffing with tcpdump 44:13 How Network Firewalls Work 45:09 AWS Security Groups Explained 47:53 Ubuntu Firewall (UFW) Basics 49:18 Linux iptables and Netfilter 52:41 Conclusion and Next Steps