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--- |
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description: Diagnose LAN connectivity issues by pinging gateway and testing network |
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tags: [network, diagnostics, connectivity, gateway, troubleshooting, project, gitignored] |
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--- |
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You are helping the user diagnose LAN connectivity issues. |
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## Process |
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1. **Identify network configuration** |
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- Run `ip addr show` to check network interfaces |
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- Run `ip route show` to identify default gateway |
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- Check DNS servers: `cat /etc/resolv.conf` |
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2. **Test gateway connectivity** |
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- Ping default gateway: `ping -c 4 <gateway-ip>` |
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- If gateway is unreachable, check: |
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- Network interface status: `ip link show` |
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- NetworkManager status: `nmcli device status` |
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- Physical connection (if applicable) |
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3. **Test DNS resolution** |
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- Test DNS lookup: `nslookup google.com` |
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- Try alternative DNS: `nslookup google.com 8.8.8.8` |
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- Check if DNS is the issue |
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4. **Test external connectivity** |
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- Ping external IP: `ping -c 4 8.8.8.8` |
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- Ping domain name: `ping -c 4 google.com` |
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- Traceroute to identify where packets stop: `traceroute google.com` |
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5. **Check for common issues** |
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- Firewall blocking: `sudo ufw status` |
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- IP conflicts: `arp -a` (look for duplicate IPs) |
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- DHCP issues: Check if IP is self-assigned (169.254.x.x) |
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6. **Advanced diagnostics** |
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- Check routing table: `ip route show` |
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- Monitor network traffic: `sudo tcpdump -i <interface> -c 20` |
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- Check for packet loss: `mtr <gateway-ip>` |
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## Output |
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Provide a diagnostic report showing: |
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- Network configuration summary |
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- Gateway reachability status |
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- DNS resolution status |
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- External connectivity status |
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- Identified issues (if any) |
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- Recommended fixes |
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