Network troubleshooting: Examples library

This document provides ready-to-use command examples for common troubleshooting tasks in MAAS environments. Copy, paste, and adapt them to your network.


DHCP Capture and Decode

sudo tcpdump -n -e -vv -i br0 '(port 67 or 68)' -w /tmp/dhcp.pcap

What to look for: Discover, Offer, Request, ACK sequence. Options 66/67 (next-server, bootfile). Confirm that the rack IP is correct.


Quick HTTP Path Test

curl -I http://<maas-host>/MAAS/
curl -I http://<proxy-host>:3128/

Use case: Verify metadata and proxy endpoints are reachable from the client VLAN.


TFTP Sanity Check

atftp -g -r pxelinux.0 <tftp-ip>

Use case: Confirm the TFTP service on the rack is responsive.


Netplan Validation and Rollback

sudo netplan get
sudo netplan try
sudo netplan apply

Use case: Confirm the deployed node has the correct VLAN/bond configuration.


Throughput Test

On rack or test host:

iperf3 -s

On client:

iperf3 -c <server> -P 4 -t 30

Use case: Measure performance between the node and the rack.


DNS Authoritative vs Forwarder

dig @<maas-dns-ip> <node>.maas A +noall +answer +ttlid
dig +trace archive.ubuntu.com

Use case: Confirm MAAS is authoritative for its zones and forwarding upstream correctly.


Commissioning Logs Quick Lens

tail -f /var/log/cloud-init-output.log
less /var/log/curtin/install.log

Use case: Watch the progress of commissioning or deployment in real time.


Verify Rack ↔ Region Connectivity

ss -ltnup | grep 5240
ip route get <region-ip>
journalctl -u snap.maas.rackd

Use case: Detect broken rack/region links.


Next Steps

For broader coverage, see the CLI Snippets document, which provides common MAAS commands for inspecting networks, VLANs, and events.