10c9e0d854
Complete restructure from patterns/examples/reference to technology-focused directories: • Created technology-specific directories with comprehensive documentation: - /tdarr/ - Transcoding automation with gaming-aware scheduling - /docker/ - Container management with GPU acceleration patterns - /vm-management/ - Virtual machine automation and cloud-init - /networking/ - SSH infrastructure, reverse proxy, and security - /monitoring/ - System health checks and Discord notifications - /databases/ - Database patterns and troubleshooting - /development/ - Programming language patterns (bash, nodejs, python, vuejs) • Enhanced CLAUDE.md with intelligent context loading: - Technology-first loading rules for automatic context provision - Troubleshooting keyword triggers for emergency scenarios - Documentation maintenance protocols with automated reminders - Context window management for optimal documentation updates • Preserved valuable content from .claude/tmp/: - SSH security improvements and server inventory - Tdarr CIFS troubleshooting and Docker iptables solutions - Operational scripts with proper technology classification • Benefits achieved: - Self-contained technology directories with complete context - Automatic loading of relevant documentation based on keywords - Emergency-ready troubleshooting with comprehensive guides - Scalable structure for future technology additions - Eliminated context bloat through targeted loading 🤖 Generated with [Claude Code](https://claude.ai/code) Co-Authored-By: Claude <noreply@anthropic.com>
183 lines
3.1 KiB
Markdown
183 lines
3.1 KiB
Markdown
# Network Troubleshooting Reference
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## Connectivity Issues
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### Basic connectivity tests
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```bash
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# Test connectivity
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ping <target_ip>
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ping -c 4 <target_ip> # Linux (4 packets)
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# Test specific port
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telnet <target_ip> <port>
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nc -zv <target_ip> <port> # netcat
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nmap -p <port> <target_ip>
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# DNS resolution
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nslookup <hostname>
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dig <hostname>
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host <hostname>
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```
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### Network interface debugging
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```bash
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# Show interfaces
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ip addr show
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ifconfig
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# Show routing table
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ip route
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route -n
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# Show network statistics
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netstat -i
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ss -i
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```
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## Service Issues
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### Port and process debugging
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```bash
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# Show listening ports
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netstat -tulpn
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ss -tulpn
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lsof -i :<port>
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# Find process using port
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fuser <port>/tcp
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lsof -i tcp:<port>
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# Show all connections
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netstat -an
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ss -an
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```
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### Service status
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```bash
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# Systemd services
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systemctl status <service>
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systemctl is-active <service>
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systemctl is-enabled <service>
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# Service logs
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journalctl -u <service> -f
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journalctl -u <service> --since "1 hour ago"
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```
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## Firewall Debugging
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### iptables
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```bash
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# List rules
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iptables -L -n -v
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iptables -t nat -L -n -v
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# Check if rule exists
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iptables -C INPUT -p tcp --dport 80 -j ACCEPT
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# Temporarily disable firewall
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systemctl stop iptables # CentOS/RHEL
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ufw disable # Ubuntu
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```
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### UFW (Ubuntu)
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```bash
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# Check status
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ufw status verbose
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# Show rules by number
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ufw status numbered
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# Check logs
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tail -f /var/log/ufw.log
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```
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## SSL/TLS Issues
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### Certificate debugging
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```bash
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# Check certificate details
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openssl x509 -in certificate.crt -text -noout
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openssl s_client -connect <hostname>:443 -servername <hostname>
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# Check certificate chain
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openssl s_client -connect <hostname>:443 -showcerts
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# Test SSL connection
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curl -vI https://<hostname>
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wget --no-check-certificate -O /dev/null https://<hostname>
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```
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### Certificate expiration
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```bash
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# Check expiration date
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openssl x509 -in certificate.crt -enddate -noout
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# Check remote certificate expiration
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echo | openssl s_client -servername <hostname> -connect <hostname>:443 2>/dev/null | openssl x509 -noout -dates
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```
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## DNS Issues
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### DNS server testing
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```bash
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# Test specific DNS server
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nslookup <hostname> <dns_server>
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dig @<dns_server> <hostname>
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# Flush DNS cache
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# Linux (systemd-resolved)
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systemctl restart systemd-resolved
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# Linux (nscd)
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systemctl restart nscd
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```
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### DNS configuration
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```bash
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# Check DNS settings
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cat /etc/resolv.conf
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cat /etc/systemd/resolved.conf
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# Test DNS resolution order
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getent hosts <hostname>
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```
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## Performance Issues
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### Bandwidth testing
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```bash
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# iperf3 testing
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# Server: iperf3 -s
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# Client: iperf3 -c <server_ip>
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# wget speed test
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wget -O /dev/null http://speedtest.tele2.net/100MB.zip
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```
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### Network latency
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```bash
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# Continuous ping with timestamps
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ping -D <target>
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# MTR (better than traceroute)
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mtr <target>
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mtr --report <target>
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```
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## Quick Diagnostics
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### One-liner network check
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```bash
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# Basic network health
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ping -c 1 8.8.8.8 && echo "Internet OK" || echo "No Internet"
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# Service accessibility
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nc -zv localhost 80 && echo "HTTP service running" || echo "HTTP service down"
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```
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### Network interface stats
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```bash
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# Interface statistics
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cat /proc/net/dev
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watch -n 1 cat /proc/net/dev
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``` |